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Naming Of Organic Compounds Containing A Functional Group

Prefix and suffix names of a few common functional groups and their decreasing order of priority are given in the table.

It may be noted that the groups -R, -OR, -NO₂, -X, etc. are considered as substituents and are indicated as prefixes.

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1. Longest chain– The parent chain is the one which has a functional group directly attached to it, even if it violates the longest chain rule.
2. Numbering of parent chain-The numbering should be done in such a way that the carbon linking to the functional group gets the lowest number even if it violates the lowest sum rule or locant rule. When the functional group itself contains carbon atom, then that carbon atom is assigned as number 1.
3. Naming of compounds with polyfunctional group- If there is more than one functional group present in a compound, then one of the functional group is chosen as the principal functional group (secondary suffix) and the remaining functional groups are treated as (substituents) subordinate functional groups.

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The functional group with higher priority in the sequence given below is termed as principal functional group.

Nomenclature Of Substituted Benzene Compounds

Benzene is a six-membered cyclic compound with alternate single and double bonds. It is represented in any one of the following ways:

1. Naming of monosubstituted benzene

It is derived by adding the name of the substituent with the word benzene. Substituent + benzene 23/11 substituted benzene

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Naming of monosubstituted benzene Example:

Special names of some monosubstituted benzene compounds

Naming of organic compounds containing functional groups NEET notes

If the functional group is attached to the carbon chain connected to benzene ring, then benzene ring is considered as a substituent and is prefixed before the root word as phenyl.

2. Naming of disubstituted benzene

If the substituents are the same: In such case, the relative position of the substituents must be indicated by adding the symbols o – (1, 2); m – (1, 3) ; p – (1, 4).

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Naming of disubstituted benzene Example:

If the two substituents are different: The substituents are named in alphabetical order.

If there are more than two substituents: The numbering is done in such a way that it satisfies the lowest sum rule.

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Nomenclature Of Bicyclo Compounds

Bicyclo Compounds

Bicyclo compounds contain two fused rings with the help of a bridge. We use the name of the alkane corresponding to the total number of carbon atoms as the base name.

1. The carbon atoms common to both the rings are called bridgeheads, and each bond or chain of atoms connecting the bridgehead atoms is called a bridge.
2. While naming the bi-cycloalkane we write an expression between the word bicyclo and alkane (in square bracket), that denotes the number of carbon atoms in each bridge. The numerals are written in descending order and the numbers are separated by a point.
3. If substituents are present, we number the bridged ring system beginning at one bridgehead, proceeding first along the longest bridge to the other bridge head, then along the second next longest bridge back to the first bridge head. The shortest bridge is numbered in the last.

Nomenclature of Bicyclo compounds Example:

Nomenclature Of Organic Compounds

The nomenclature deals with the naming of millions of organic compounds. The following systems are employed.

1. Trivial system (common system): It is the oldest system of naming organic compounds. In the early stages of the development of organic chemistry, organic compounds were named after the source from which they were first isolated. Generally, the names chosen had Latin or Greek roots. The following illustrations justify the statement.

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NEET organic chemistry nomenclature notes

Iupac Nomenclature

IUPAC nomenclature of organic compounds for NEET

2. IUPAC System – Saturated hydrocarbons are the parent compounds and other organic compounds as their derivatives obtained by substituting one or more hydrogen atoms with functional groups. IUPAC name of any organic compound may consist of three parts. “prefix-root word-suffix”.

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Root word- is assigned to organic molecule based on the number of carbon atoms present in the main parent chain

IUPAC naming of organic compounds chart for NEET

Suffix – is based on the nature of bonds and functional group present in the molecules. It is of 2 types,

(1) Primary suffix: A primary suffix is added next to the root word to indicate whether the parent chain is saturated or unsaturated.

Note: A carbon-carbon double bond or triple bond must be included in parent chain even if it contains less number of carbon atoms.

(2) The secondary suffix added next to the primary suffix to indicate the presence of a functional group in organic compounds which determines the class of organic compounds.

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Secondary suffixes of a few functional groups are given.

Note – While adding the secondary suffix, the letter ‘e’ of the primary suffix (i.e., ane, ene, and yne) is dropped if the secondary suffix begins with a vowel (a, e, i, o, or u). It is retained if a secondary suffix begins with a consonant.

3. Prefix (substituent): All the groups which are not names in parent chain and functional groups are called as substituents. Its name placed before the root word. Example: – Alkyl group, halo atoms, nitro group

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Alkyl Groups

Alkyl groups  derived from an alkane, by removing a hydrogen atom bonded to carbon. These groups are named simply by dropping -ane from the name of the corresponding alkane and replacing it by -yl. R is a general symbol, general formula for an alkyl group is C_nH_2n+1, because it contains one less hydrogen atom than the parent alkane, C_nH_2n+2.

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Among the alkyl groups we encounter the problem of isomerism.

• While only one alkyl group can be derived from methane (the methyl, CH₃-)
• Ethane (the ethyl, CH₃CH₂-)
• Two or more alkyl groups can be derived from higher alkanes.

Alkyl groups Examples

1. From propane (C₃H₈), two alkyl groups can be derived. Removal of one of the hydrogens from one of the end carbon atoms gives an alkyl group that is called the propyl group or n-propyl group.

Removal of one of the hydrogens from the middle carbon atom gives an alkyl group that is called the isopropyl group.

Both these alkyl groups contain the propane chain but differ in the point of attachment of the group to the rest of the molecule.

2. There are four butyl groups, two derived from the straight-chain n-butane, and two derived from the branched-chain isobutane. These are given the designations: n- (normal), sec¬secondary), iso-, and tert- (tertiary) as shown below:

An alkyl group is described as,

• Primary if the carbon at the point of attachment is bonded to only one other carbon,
• As secondaryif bonded to two other carbons,
• Tertiary if bonded to three other carbons. Thus, if r is any hydrocarbon radical, the different kinds of alkyl groups are

RCH₂ -Primary

R₂CH– Secondary

R₂C- Tertiary

Alkyl Group Problems

Problem 1: Classify each of the following alkyl groups as primary, secondary, or tertiary: Butyl, Isopropyl, Isobutyl, sec-butyl, and tert-Butyl.

Solution:

Best notes for organic chemistry nomenclature NEET

EPrefix n-(normal) is used for those alkanes in which all the carbon atoms form a continuous chain with no branching.

CH₃CH₂CH₂CH₃ (n-butene)

CH₃CH₂CH₂CH₂CH₃ (n-pentane)

EPrefix iso is used for those alkanes in which one methyl group is attached to the next-to-end carbon atom (second last) of the continuous chain.

EPrefix neo is used for those alkanes which have two methyl groups attached to the second last carbon atom of the continuous chain.

Rules for naming of open chain Organic compound.

Iupac Nomenclature Rules

Rule 1 – Longest chain rule (root word rule): The continuous carbon chain containing maximum carbon atoms including the function group is selected. It is called the parent chain. For one to four carbon atoms of the parent chain, special root words are used but for chains of five or more carbon atoms Greek number roots are employed.

The generic root word for any parent chain is ‘alk’.

Similarly, the following hydrocarbon will be regarded as a substituted hexane because the longest continuous carbon chain (parent chain/ root chain) contains six carbon atoms.

Note – If two different chains of equal length are possible, the chain with maximum number of side chains or alkyl groups is selected. The number used to specify the position of the substituents is called locant.

Rule 2 – Lowest sum rule (rule of locant): Parent carbon chain is numbered using Arabic numerals 1, 2, 3, 4, and 5 in such a way that functional groups or substituents containing carbon receive least number.

E When the parent chain contains two or more substituents, the numbering is done from the end where the sum of the locants is least.

E Parent chain with one substituent: Prefix the name of the substituent to the root word of parent chain and indicate its position. The name of the substituent is separated from its locant by a hyphen (-). The name of the organic compound is written as one word.

E Naming of different substituents: When two or more different substituents are present on the parent chain, they are named in alphabetical order along with their appropriate locants.

E Numbering of different substituents at equivalent positions: If two different alkyl or halo groups are present at equivalent positions, the numbering of the parent chain is done in such a way that the substituent which comes first in the alphabetical order gets the lower number.

E Presence of the same substituent more than once: If the same substituent occurs more than once, the prefixes di, tri, tetra are prefixed to the name of the substituent. It may be noted that the position and name of the substituent are separated by a hyphen (-) whereas the numerals representing the positions of the substituents are separated by commas.

E Naming a complex substituent: In case the substituent on the parent chain is complex (i.e., it has a branched chain), it is named as a substituted alkyl group by numbering the carbon atom of this group attached to the parent chain as 1. The name of complex substituent is enclosed in the bracket to avoid confusion with the numbers of parent chain.

If same complex substituent occurs more than once on the parent chain, prefixes bis, tris, tetrakis, etc., are used before the name of the complex substituent. The application of IUPAC rules to the structure of a molecule to arrive at IUPAC name is illustrated as follows.

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• Parent chain has 5 carbon atoms, and it has more substituents. The root word is ‘pent’.
• The primary suffix is ‘ane’
• Sum of locants is 9, the substituent that comes first in alphabetical order gets the lower number.
• Prefixes to the rootword are bromo, ethyl, and methyl. Hence, IUPAC name is “2-bromo-3-ethyl-4-methyl pentane”

A few examples are given below:

 

Functional Groups

Functional Groups Definition:

A functional group is defined as “an atom or group of atoms present in a molecule which decides the chemical properties of the organic compounds”. Double and triple bonds are also considered as functional groups.

The organic compounds are further classified into different classes depending upon the nature of functional group.

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Classification of organic compounds based on functional group is summarised in the table.

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Homologous Series

A series of structurally related organic compounds with a same functional group can be represented by a general formula and differ by -CH₂ group is called homologous series. The individual members of such series is called homolouge and this phenomenon is known as homology.

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Characteristics of a homologous series are as follows.

• Each homologues series can be represented by general molecular formula.
• Exp – General molecular formula of alkane is C_nH_2n+2. Molecular formula C_nH_2nO₂ represents alkanoic acids (carboxylic acids) and alkyl alkanoates (esters).
• All the members of a given homologous series (homologues) possess the same functional group.
• The successive members of a homologous series differ by a -CH₂– group or by mass units.
• Homologues of a homologous series can be prepared by general methods.
• The physical properties such as boiling point, melting point, density, etc., of the members of a homologues series show a regular gradation with increase in molecular mass.
• Chemical properties of the members of a homologous series are similar though the first homologue may vary considerably from the rest of the homologues.

Classification Of Organic Compounds

Organic Compounds

The compounds with C and H are called hydrocarbons. Organic compounds are considered as the derivatives of hydrocarbons obtained by replacing H-atoms by other atoms or groups. Based on the C – skeleton, organic compounds are divided as below,

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Acyclic Compounds

The open-chain organic compounds are called acyclic compounds. The carbon chains may be linear or branched. The open-chain compounds are classified into two groups.

Saturated compounds: Open-chain compounds in which carbon atoms of parent chain are bonded with single bonds are called saturated acyclic compounds.

Saturated compounds Example:

NEET General Organic Chemistry Classification of Organic Compounds Notes

Unsaturated compounds: The open-chain organic compounds in which parent chain contains one or more carbon-carbon double bonds or triple bonds are called unsaturated acyclic compounds.

Unsaturated compounds Example:

Functional Groups and Homologous Series NEET Notes

Cyclic Compounds

Here carbon atoms are linked by covalent bonds to form ring structures are called cyclic compounds. Depending upon the constituents of ring, these compounds are further classified into two groups.

Carbocyclic compounds(Hoinocydiccoinpoimds): The cyclic compounds containing only carbon atoms in their ring are called carbocyclic compounds. They are further divided into two groups.

Alicyclic compounds

The carbocyclic compounds which resemble with aliphatic compounds in most of their properties are called alicyclic compounds.

Classification of Organic Compounds NEET Notes

NEET Chemistry Classification of Organic Compounds Important Notes

Aromatic Compounds

Benzene is the parent aromatic hydrocarbon. The organic compounds containing one or more isolated or fused benzene rings and their functionalised derivatives are called aromatic compounds or benzenoid compounds.

Aromatic compounds example:

The aromatic compounds that resemble benzene in most of their properties are called non-benzenoid aromatic compounds

Non-Benzenoid Aromatic compounds For example:

Classification of Organic Compounds NEET Key Concepts and Summary

Heterocyclic Compounds

The cyclic compounds containing one or more heteroatoms (atom other than C it may be O, N, S, etc.,) in their ring are called heterocyclic compounds. Depending upon their chemical behaviors, they are further classified into two groups.

Alicyclic heterocyclic compounds: The aliphatic cyclic compounds containing one or more hetero atoms in their ring are called alicyclic heterocyclic compounds.

Alicyclic heterocyclic compounds For example:

Aromatic heterocyclic compounds: The aromatic cyclic compounds containing one or more hetero atoms in their molecules are called aromatic heterocyclic compounds.

Aromatic heterocyclic compounds For example:

NEET Chemistry General Organic Chemistry (GOC) Chapter Classification of Organic Compounds Notes

General Organic Chemistry Introduction

Chemistry

‘The branch of chemistry dealing with these compounds, which are widely distributed in nature and play an important role in our daily lives’, is called organic chemistry.

In the earlier period of development of chemistry, compounds were classified into two types:

1. Organic compounds derived from ‘living matter’ (plants and animals).
2. Inorganic compounds prepared from ‘non-living matter’ (mineral sources).

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Berzelius, a Swedish chemist proposed the mistaken notion that a ‘vital force’ present in living matter was essential for the synthesis of organic compounds. However, the synthesis of urea an organic compound present in urine, from ammonium cyanate, an inorganic compound by Frederich Wohler in 1828 effectively destroyed the myth of organic compounds being associated with a ‘vital force’.

Soon afterwards the pioneering work of Herman Kolbe who synthesized acetic acid and of Berthelot who synthesized methane showed conclusively that organic compounds are essentially the compounds formed by carbon with itself and other elements and that they can be synthesized in a laboratory as easily as inorganic compounds.

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The chemistry of hydrocarbons and their derivatives constitutes organic chemistry.

The number of organic compounds available today are more compare to total inorganic compounds of all elements except carbon. This is due to unique catenation property of Carbon.

Catenation: is the property of an element where a large number of its own atoms join together through covalent bonds. Due to which it forms single as well as multiple covalent bonds with other carbon atoms.

It is further supplemented by the fact that it also forms covalent bonds with atoms of other elements like hydrogen, oxygen, nitrogen, Sulphur, phosphorus, and halogens in a variety of ways (i.e., single and multiple bonds). This property gives a scope for the Chemists to synthesize new compounds.

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Tetravalency Of Carbon Atom

The atomic number of carbon is 6 and it has four electrons in its valence shell. In order to acquire a stable noble gas configuration, it can share its 4 electrons with the electrons of its atom or electrons of other atoms to form four covalent bonds. The bonds can be sigma(σ) or pi(π).

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The type of bond determines the hybridization of carbon atoms and the geometry of the molecules.

Hybridisation In Carbon Compounds

Hybridization is defined as the intermixing of degenerate orbitals (orbitals at nearly the same energy) to produce an entirely equivalent number of new orbitals of same energy, identical shapes and symmetrically disposed of in planes. The orbitals formed are called hybrid orbitals.

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• The orbitals of an isolated atom can undergo hybridization.
• Number of hybrid orbitals generated are equal to number of contributing atomic orbitals.
• The hybrid orbitals orient in space providing definite geometry to molecules or ion.
• Like atomic orbital, a hybrid orbital cannot have more than two electrons of opposite spins.

There are three types of hybridization,

1. sp³ hybridization (contain saturated organic compounds with only single covalent bonds)
2. sp² hybridization (here organic compounds having carbon atoms linked by double bonds)
3. sp hybridization (here organic compounds having carbon atoms linked by a triple bonds).

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Prediction of hybridization It can be done by two methods,

1. First Method: In this method hybridization can be known by the number of bonds present on that particular atom.

First Method Examples:

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2. Second Method: (Electron pair method)

The hybridized state of an atom of a molecule or an ion or radical can be predicted by calculating number of orbitals or electron pairs involved in hybridization (H) which is evaluated as follows.

H = (number of a bonds formed with adjected atom/s + number of lone pairs of electrons)

∴ ep = bp + lp;

where, ep = electron pair present in hybrid orbitals,

bp = bond pair present in hybrid orbitals

Number of bp = Number of atoms attached to the central atom of the species (do not include π electron pairs).

Number of lp’s can be determined as follows,

1. If carbon has – bonds or positive charge or odd electron, thanlp on carbon will be zero.
2. If carbon has negative charge, then Ip will be equal to one.

Second Method Example:

Applications Of Hybridisation

1. Size of the hybrid orbitals: Since – orbitals are closer to the nucleus than – orbitals, it is reasonable to expect that greater the character of an orbital the smaller it is. Thus, the decreasing order of the size of the three hybrid orbitals is opposite to that of the decreasing order of orbital character in the three hybrid orbitals. sp³ > sp² > sp

2. Electronegativity of different orbitals

1. The electronegativity of s-orbital is maximum.
2. Electronegativity of hybrid orbital ∝ % s-character in hybrid orbitals
   • Thus Sp-hybrid carbon is electronegative and it is electropositive in character and sp³-hybrid carbon can behave as electropositive in character sp² -hybrid carbon can behave as electropositive (in carbocation) as well as electronegative (in carbanion) in character.
3. Electronegativities of different hybrid and nonhybrid orbitals in decreasing order is as follows

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3. ond length variation in hydrocarbons

⇒ \(\% \text { of s orbital character } \propto \frac{1}{\mathrm{C}-\mathrm{C} \text { bond length }} \propto \frac{1}{\mathrm{C}-\mathrm{H} \text { bond length }}\)

4. Bond strength in hydrocarbons: The shorter is the bond length, the greater is the compression between atomic nuclei, and hence greater is the strength of that bond.

Structural Representation Of Organic Compounds

Structural formula (structure) is the sequence in which different atoms constituting the molecule are bonded to one another. Structures of molecules of organic compounds can be described in various ways.

The most common types of representations are:

1. Lewis structure (or electron dot structure) Here dots are used to represent all of the valence electrons of all the bonded atoms in the molecule:

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Writing dot structure is tedious and time-consuming. The other representations are more convenient and are, therefore, more often used.

2. Dash structural formula The Lewis structure can be simplified by representing a shared electron pair by a ‘stick’ (dash, -) between the bonded atoms. When there is one dash between two atoms, the atoms are said to be bonded by a single covalent bond.

• A double covalent bond, in which two pairs of electrons are shared, is shown by two dashes between the atoms. A triple bond is represented by three dashes between the atoms. The valence electrons that are not included in covalent bonds are called nonbonding electrons (lone pairs). These are assigned to specific atoms and are represented by dots drawn next to the symbols for these atoms.
• Lone pair of electrons on hetero atoms (for example, oxygen, nitrogen, sulphur, phosphorus, halogens) may or may not be shown. Such structural formulae which focus only on the valence electrons involved in bond formation are called complete structural formulae.

3. Condensed structural formula Complete structural formulae can be shortened by leaving out some or all of the covalent bonds and by denoting the number of identical groups attached to an atom by a subscript. The resulting description of the molecule is called a condensed structural formula. Thus,

CH₃CH₃ or C₂H₆ Ethane

H₂C = CH₂ or C₂H₄ Ethene

HC ≡ CH or C₂H₂ Ethyne

CH₃CH₂Cl or C₂H₅Cl Ethyl Chloride

CH₃CH₂CH₂OH or CH₃(CH₂)₂OH Methanol

CH₃CH₂CH₂CH₂CO₂H or CH₃(CH₂)₃CO₂H Pentanoic Acid

Condensed structural formulae are easier to write than dash formulae. In condensed formulae, all of the hydrogen atoms that are attached to a particular carbon are usually written immediately after the carbon. In fully condensed formulae, all of the atoms that are attached to the carbon are usually written immediately after that carbon, listing hydrogens first.

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For example, the condensed formula for isopropyl alcohol can be written in four different ways:

4. Bond-line structural formula: For further simplification, only lines are used to represent the structures of organic molecules. In this bond-line structural formula of organic molecules, carbon, and hydrogen atoms are not shown. The lines denoting the carbon-carbon bonds are drawn in a zig-zag fashion. The only atoms especially written are the hetero atoms (oxygen, nitrogen etc). They are neither carbon nor hydrogen bonded to carbon.

The termini describe methyl (CH₃-) groups (unless denoted otherwise by a functional group). The line junctions indicate carbon atoms bonded to suitable number of hydrogens needed to satisfy the covalency of the carbon atoms: Thus

The bond-line representation is the quickest of all to write because it shows only the carbon skeleton.

Ring or cyclic compounds: An organic compound in which carbon atoms are not bonded in chain but are bonded in closed structures called rings are known as cyclic compounds. Such a compound containing one or more rings is represented by drawing the suitable ring (polygon) without indicating the carbon and hydrogen atoms. The corner of the polygon denotes a carbon atom and its sides represent a carbon-carbon bond. An atom or a group of atoms (other than hydrogen) bonded to the carbon is however shown in the structure.

Bond-line formulae of some cyclic compounds are:

Multiple bonds are also indicated in bond-line formulae.

Multiple bonds example:

Structural Representation Of Organic Compounds Examples

Example 1: Convert each of the following Lewis structures into complete structural formulae:

Solution: Use the dash to represent the shared electron pair.

Example 2: Convert each of the following complete structural formulae into condensed formulae.

Solution: Omitting some or all of the dashes and indicating the number of identical groups by a subscript we get

1. HO(CH₂)₂NH₂
2. CH₃C=C(CH₂)₃CH₃
3. H₃CCOCH₃
4. CH₃(CH₂)₃NO₂

Example 3: Write the condensed structural formulae for the compound that follows in different ways.

Solution:

Example 4: Write the bond-line formula for

Solution: First, outline the carbon skeleton, including the OH group as follows:

Thus, the bond-line formula is

Example 5: For each of the following condensed formulae write the corresponding bond-line formula.

1. (CH₃)₂CH(CH₂)₂CH₂OH
2. CH₃(CH2)₄CHICH₂CHO
3. (CH₃)₂CHCH₃CH(CH₂)₃NO₂
4. (CN)₂CHCH₂COCl

Solution:

In the bond-line formula carbon and hydrogen atoms except those that are part of the functional groups are not shown. We show only the carbon skeleton. The number of hydrogen atoms necessary to fulfill the carbon atoms’ valences are assumed to be present, but we do not write them in.

Other atoms (for example, Cl, O, N) are written in. Each intersection of two or more lines and the end of a line represent a carbon atom unless some other atom is written in.

Example 6: Draw all possible bond-line formulae for a cyclic compound, C₅H₁₀.

Solution: Start with the maximum number of carbon atoms in the ring and move towards the ring of 3 carbon atoms. Explore all sorts of possibilities on this route:

Three-dimensional representation of organic molecules

None of the formulae that we have described so far convey any information about how the atoms of a molecule are arranged in space. Shape or the three-dimensional (3-D) structure of organic molecules can be described on a paper (two-dimensional) by exploring certain conventions. For instance, by using solid and dashed wedge formula the 3-D image of an organic molecule can be perceived on a two-dimensional paper.

In solid-wedge and dashed-wedge description the solid-wedge denotes a bond projecting out of the plane of the paper towards the viewer. The dashed wedge depicts the bond projecting behind the plane of the paper and going away from the viewer. Both the wedges are drawn in such a way that the broad end of the wedge is near the viewer. The other two bonds lying in the plane of the paper are shown by using a normal line (________).

Let’s consider the wedge- and dashed-wedge representation of methane (CH₄) molecule: The two carbon-hydrogen bonds represented by normal lines are in the plane of paper, whereas the carbon-hydrogen bond represented with a solid wedge is aimed to be in front of the plane of paper.

The hydrogen bonded to carbon by dashed edge is intended to be behind the plane of paper. Note that the carbon atom is lying in the plane of paper. Wedge and dashed-wedge formulae are important tool for clearly showing three dimensions.

Nomenclature Of Organic Compounds

Question 1. The IUPAC name of the compound (CH₃)₂CH-CH=CH-CHOH-CH₃ is

1. 5-methyl-hex-3-en-2-ol
2. 2-methyl-hex-3-en-5-ol
3. 2-hydroxy-5-nethyl-3-hexene
4. 5-hydroxy-2-methyl-3-hexene

Answer: 1. 5-methyl-hex-3-en-2-ol

Solution: Follow IUPAC rules.

The IUPAC name of the compound (CH₃)₂CH-CH=CH-CHOH-CH₃ is 5-methyl-hex-3-en-2-ol

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Question 2. Which of the following represents the condensed formula for pentanes?

1. CH₃(CH₂)₃CH₃
2. (CH₃)₃CCH₃
3. (CH₃)₂CHCH₂ CH₃
4. All of these

Answer: 4. All of these

Solution: In condensed structural formula, parenthesis is used for the identical groups of atoms.

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Question 3. Which is the most stable carbocation?

1. isopropyl cation
2. Triphenylmethyl cation
3. Ethyl cation
4. n-propyl cation

Answer: 2. Triphenylmethyl cation

Solution: Aryl carbonium ions are more stable than the alkyl carbonium ions. The order of stability of carbocation is

Triphenyl methyl >Diphenyl methyl> Benzyl>Allyl>30>2°>1°> methyl carbocation.

Question 4. Which of the following is phenyl ethanoate?

Answer: 3

Solution: Esters are named by prefixing the name of the alkyl or aryl group (of OR’ part) before the name of the parent acid and changing the suffix “ic” acid to ate. Hence, the structure of phenyl ethanoate is

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Question 5. IUPAC name of CH₂=CH—CH(CH₃)₂ is:

1. 1,1-dimethyl-2-propene
2. 3-methyl-1-butene
3. 2-vinyl propane
4. 1-isopropyl ethylene

Answer: 2. 3-methyl-1-butene

Solution: Follow IUPAC rules.

NEET chemistry nomenclature MCQs with answers

Question 6. In the structure, the number of carbon atoms are:

1. One primary, two secondary and one tertiary
2. Four primary, two tertiary and one secondary
3. One primary, one secondary, one tertiary and one quaternary
4. Five primary, one secondary, one tertiary and one quaternary

Answer: 4. Five primary, one secondary, one tertiary and one quaternary

Solution: A primary carbon is one which is joined to one carbon atom. A secondary carbon atom is joined to two carbon atoms and the tertiary carbon is attached to three carbon atoms. A quaternary carbon has all its four valencies attached to carbon atoms.

Question 7. IUPAC name of the following compound is

1. 3, 5-dimethylcyclohexene
2. 3, 5-dimethyl-1-cyclohexene
3. 1, 5-dimethyl-5-cyclohexene
4. 1, 3-dimethyl-5-cyclohexene

Answer: 1. 3, 5-methylcyclohexane

Solution: Its IUPAC name is 3,5-dimethylcyclohexene.

Important nomenclature questions for NEET organic chemistry

Question 8. IUPAC name ofis

1. N, N- dimethylethanolamine
2. N-methyl, N-ethylmethanamine
3. Dimethyl-ethylamine
4. None of the above

Answer: 1. N, N- dimethylethanolamine

Solution: Follow IUPAC rules.

Question 9. The IUPAC name of CH₃-CH=CH-C=CH is

1. Pent-3-en-1-yne
2. Pent-3-en-4-yne
3. Pent-2-en-4-yne
4. Pent-2-en-3-yne

Question 10.

1. 1-amino prop-2-enal
2. 3-amino prop-2-enal
3. 1-amino-2-formyl ethene
4. 3-amino-1-oxoprop-2-ene

Answer: 2. 3-amino prop-2-enal

Solution: Follow IUPAC rules.

Question 11. The IUPAC name of an unsymmetrical ether with the molecular formula of C₄H₁₀O is

1. Ethoxy propane
2. Methoxy ethane
3. Ethoxy ethane
4. Methoxy propane

Answer: 4. Methoxy propane

Solution: Only two unsymmetrical ethers are possible from the formula C₄H₁₀O viz

CH₃ CH₂ CH₃-O-CH₃

Question 12. IUPAC name of urea is:

1. Diamino ketone
2. 1-aminoethanamide
3. 1-aminomethanamide
4. amino acetamide

Question 13. IUPAC name of C₆ H₅ CN is:

1. Phenyl nitrile
2. Benzene nitrile
3. Benzyl nitrile
4. Phenyl cyanide

Answer: 2. Benzene nitrile

Solution: Follow IUPAC rules.

Question 14. The IUPAC name of the compound is

1. 2(carboxymethyl)-pentane-1,5-dioic acid
2. 3-carboxy hexane-1, 6-dioic acid
3. Butane-1, 2, 4-tricarboxylic acid
4. 4-carboxy hexane-1, 6-dioic acid

Answer: 2. 3-carboxy hexane-1, 6-dioic acid

Solution: IUPAC name of the above compound is 3-carboxyhexane-1, 6-dioic acid.

NEET organic chemistry IUPAC naming practice questions

Question 15. IUPAC name of

1. Dimethyl amine
2. 2-amino propane
3. Isopropyl amine
4. 2-propanamide

Answer: 4. 2-propanamide

Solution: 2-propanamide

Question 16. The IUPAC name of

1. 1, 1-dimethyl-1, 3-butanediol
2. 2-methyl-2, 4-pentanediol
3. 4-methyl-2, 4-pentanediol
4. l, 3, 3-trimethyl-1, 3-propanediol

Answer: 2. 2-methyl-2, 4-pentanediol

Solution: Follow IUPAC rules.

Question 17. The IUPAC name of the compound is

1. 2,4-dimethylhexanone-3
2. 2,6-dimethylheptanone-4
3. 2,6-dimethylhexanone-4
4. 2,6-dimethylheptanone-5

Answer: 2. 2,6-dimethylheptanone-4

Solution: Follow IUPAC rules.

Question 18. Lactic acid is:

1. Propionic acid
2. ^-hydroxy propanoic acid
3. a-hydroxy propanoic acid
4. None of the above

Answer: 3. a-hydroxy propanoic acid

Solution: Lactic acid is also called as a-hydroxy propionic acid or 2-hydroxy propanoic acid.

Question 19. The compound which contains all the four 1°, 2°, 3° and 4° carbon atoms is

1. 2, 3-dimethyl pentane
2. 3-chloro-2, 3-dimethyl pentane
3. 2, 3, 4-trimethylpentane
4. 3, 3-dimethyl pentane

Answer: 2. 3-chloro-2, 3-dimethyl pentane

Solution: 3-chloro-2, 3-dimethyl pentane contains all the four 1°,2°, 3° and 4° carbon atoms.

Question 20. The name formic acid was given for HCOOH because it was prepared from:

1. Acetum
2. Ant
3. Wood
4. Oxalis plant

Answer: 2. Ant

Solution: Formic acid was obtained from ant (Formica in Greek). This is the trivial name for HCOOH.

Question 21. The IUPAC name of the compound having the formula CH= C — CH=CH₂ is:

1. 1-butene-3-yne
2. 3-butene-1-yne
3. 1-butyn-3-ene
4. But-1-yne-3-ene

Answer: 1. 1-butene-3-yne

Solution: Follow IUPAC nomenclature.

Question 22. The IUPAC name of the below compound is

1. 1- cyclohexane-2,4-dienylethanone
2. 3- cyclohexane-2,4-dienylethanone
3. 1- cyclohexane-3,5-dienylethanone
4. 3- cyclohexane-3,5-dienylethanone

Answer: 1. 1- cyclohexane-2,4-dienylethanone

Solution: Follow IUPAC nomenclature.

Question 23. The IUPAC name of the below compound is

1. 1-methyl-1-amino propane
2. 2-amino butane
3. 2-methyl-3-amino propane
4. None of the above

Answer: 2. 2-amino butane

Solution: Follow IUPAC rules.

Question 24. The correct IUPAC name of (C₂ H₅)₄ C is:

1. Tetraethyl methane
2. 2-ethyl pentane
3. 3,3-diethyl pentane
4. None of these

Answer: 3. 3,3-diethyl pentane

Solution: Follow IUPAC rules.

Nomenclature of organic compounds NEET question bank

Question 25. Which IUPAC name is wrong?

Answer: 3

Solution: It is 3-methyl butan-2-ol.

Question 26. The structural formula of 2,2,3-trimethyl hexane is:

Answer: 3

Solution: Follow IUPAC rules.

Question 27. IUPAC name of acraldehyde is

1. But-3-en-1-al
2. Propenyl aldehyde
3. But-2-ene-1-al
4. Prop-2-en-1-al

Answer: 4. Prop-2-en-1-al

Solution: IUPAC name of acraldehyde

Question 28. The IUPAC name of the compound is

1. 2-chloro-4-methyl-2-pentene
2. 4-chloro-2-methyl-3-pentene
3. 4-methyl-2-chloro-2-pentene
4. 2-chloro-4, 4-dimethyl-2-butene

Answer: 1. 2-chloro-4-methyl-2-penton

Solution: Follow IUPAC rules.

Question 29. 2-methyl pent-3-ene is achiral because it has:

1. A centre of symmetry
2. A plane of symmetry
3. Symmetry at C₂ carbon
4. Both centre and a plane of symmetry

Answer: 4. Both centre and a plane of symmetry

Solution: If the structure of the compound is drawn then we find that a plane of symmetry is present in this compound. The two halves are equal hence the compound does not have a chiral point, in addition to this it has a Centre. The two sides of the compound on the different sides of the centre atom are similar. Both the reasons are present which signifies that the molecule is achiral.

Question 30. The IUPAC name of the compound is

1. 3,4-dimethyl-3-n-propyl nonane
2. 4-ethyl-4,5-dimethyl decane
3. 6,7-dimethyl-7-n-propyl nonane
4. 6,7-dimethyl-7-ethylene

Answer: 2. 4-ethyl-4,5-dimethyl decane

Solution: Follow IUPAC rules.

Question 31. Give the correct IUPAC name for

1. 2-ethoxy-5-chloroethane
2. l-chloro-4-ethoxy-4-methyl butane
3. 1-chloro-4-ethoxy pentane
4. Ethyl-1-chloropentylether

Answer: 1. 2-ethoxy-5-chloroethane

Solution: According to the IUPAC system, ether is named as alkoxy alkane. The larger alkyl group forms the parent chain while the lower alkyl group takes in ethereal oxygen and forms a part of the alkoxy group.

Question 32. The IUPAC name of the compound, CH₃ CH = CHC = CH is:

1. Pent-4-yn-2-ene
2. Pent-3-en-1-yne
3. Pent-2-en-4-yne
4. Pent-1-yn-3-ene

Answer: 2. Pent-3-en-1-yne

Solution: Follow IUPAC rules.

Question 33. The IUPAC name of C₆ H₅ COCl is

1. Benzoyl chloride
2. Benzene chloro ketone
3. Benzene carbonyl chloride
4. Chloro phenyl ketone

Answer: 1. Benzoyl chloride

Solution: Follow IUPAC rules.

NEET chemistry IUPAC nomenclature quiz with answers

Question 34. IUPAC name of the compound

1. 5- methyl-4-isopropyl-6, 6’diethyloctane
2. 3, 3-dimethyl, 3-ethyl-5- isopropyl octane
3. 3, 3-diethyl-4-methyl-5-(1,1-dimethyl) octane
4. 3, 3- diethyl-4-methyl-5-(1’-methylethyl) octane

Answer: 4. 3, 3- diethyl-4-methyl-5-(1’-methyl ethyl) octane

Solution: Select the longest possible carbon atom chain, number it and name the compound according to IUPAC rules.

Question 35. The IUPAC name of is

1. But-3-enoic acid
2. But-1-enoic acid
3. Pent-4-enoic acid
4. Prop-2-enoic acid

Question 36. The correct IUPAC name of the below molecule is

1. Isopropyl benzene
2. Cumene
3. Phenyl isopropanol
4. 2-phenyl propane

Answer: 4. 2-phenyl propane

Solution: Follow IUPAC rules.

Question 37. The IUPAC name of the compound is

1. 2-methyl pent-1-en-4-yne
2. 4-methyl pent-4-en-1-yne
3. 2-methyl pent-2-en-4-yne
4. 4-methyl pent-1-en-4-yne

Answer: 1. 2-methylpent-1-en-4-yne

Solution: Follow IUPAC rules.

Question 38. Freon-114 is an organic compound. k is chemically called 1,2dichlorotetrafluoroethane. Its correct structural formula is:

Answer: 3

Solution: Follow IUPAC rules.

Question 39. The IUPAC name of the following compound is

1. Propionic anhydride
2. Di propanoic anhydride
3. Ethoxy propanoic acid
4. Propanoic anhydride

Answer: 4. Propanoic anhydride

Solution: In the IUPAC system, anhydrides are named as alkanoic anhydride.

Question 40. IUPAC name of the compound is

1. 2-ethyl-3-methyl-hexa-l-en-4-yne
2. 5-ethyl-4-methyl-hexa-2-yn-5-ene
3. 3-methylene-4-methylhepta-5-yne
4. 5-methylene-5-ethyl-4-methylhepta-2-yne
5. Answer: 1. 2-ethyl-3-methyl-hexa-l-en-4-yne

Solution:-do-

Question 41. Bicyclo (1,1,0) butane is

Answer: 3

Its IUPAC name is bicyclo [1,1,0] butane.

Question 42. t-butyl alcohol is

1. 2-methyl propane-2-ol
2. 2-methyl propane-1-ol
3. 3-methyl butane-1-ol
4. 3-methyl butane-2-ol

Answer: 1. 2-methyl propan-2-ol

Solution: 2-methyl propan-2-ol is tert-butyl alcohol.

Question 43. IUPAC name of C₆ H₅ COCl is:

1. Benzal chloride
2. Benzenechloro ketone
3. Benzene carbonyl chloride
4. Chloro phenyl ketone

Answer: 3. Benzene carbonyl chloride

Solution: Follow IUPAC rules.

Question 44. The IUPAC name for tertiary butyl iodide is

1. 4-iodo butane
2. 2-iodo butane
3. 1-iodo-3-methyl propane
4. 2-iodo-2-methylpropane

Answer: 4. 2-iodo-2-methylpropane

Solution: Its IUPAC name is 2-iodo-2-methyl propane.

Question 45. The correct structure of dimethyl butane is:

1. CH₃CH₃—C=C—CH₂ CH₃
2. (CH₃)₃C —C —C≡CH
3. CH₃—C=CCH(CH₃)₂
4. 

Answer: 2. (CH₃)₃C —C —C≡CH

Question 46. Glyoxal is

1. CH₂OH-CH₂OH
2. CHO-CH₂OH
3. COOH-CO-COOH
4. CHO-CHO

Answer: 4. CHO-CHO

Solution:

Question 47. Give the IUPAC name for,

1. Ethyl-4- oxo heptanoate
2. Methyl-4- oxo heptanoate
3. Ethyl-4- oxo hexanoate
4. Methyl 4- oxo hexanoate

Answer: 4. Methyl 4- oxo hexanoate

Solution: Follow IUPAC rules.

Question 48. The IUPAC name of the compound,

1. 2-ethylbutanamide
2. 2-methylbutanamide
3. 1-amino-2-methylpropane
4. None of the above

Answer: 2. 2-methylbutanamide

Solution: Follow IUPAC rules.

Question 49. The IUPAC name of CH₃ COCH(CH₃)₂ is

1. Isopropyl methyl ketone
2. 2-methyl-3-butanone
3. 4-methyl isopropyl ketone
4. 3-methyl-2-butanone

Answer: 4. 3-methyl-2-butanone

Solution:

The keto functional group is given priority.

Question 50. The IUPAC name of the following compound is

1. Bicyclo [2,2,0] octane
2. Bicyclo [0,2,2] hexane
3. Bicyclo [2,1,1] hexane
4. Bicyclo [2,2,0] hexane

Answer: 4. Bicyclo [2,2,0] hexane

Solution: Hence, the correct IUPAC name is bicyclo [2,2,0] hexane.

Nomenclature of organic compounds NEET sample paper

Question 51. The IUPAC name of the compound,

1. 1,2-dimethyl-2-butenol
2. 3-methylpent-3-en-2-ol
3. 3,4-dimethyl-2-buten-4-ol
4. 2,3-dimethyl-3-pentenol

Answer: 2. 3-methyl pent-3-en-2-ol

Solution: Follow IUPAC rules.

Question 52. IUPAC name of (CH₃)₃ CCl is

1. n-butyl chloride
2. 3-chloro butane
3. 2-chloro 2-methyl propane
4. t-butyl chloride

Answer: 3. 2-chloro 2-methyl propane

Solution: Follow IUPAC rules.

Question 53. What is the correct IUPAC name of the compound?

1. 4-methoxy-2-nitrobenzaldehyde
2. 4-formyl-3-nitro anisole
3. 4-methoxy-6-nitrobenzaldehyde
4. 2-formyl-5-methoxy nitrobenzene

Answer: 1. 4-methoxy-2-nitrobenzaldehyde

Solution: Follow IUPAC rules.

Question 54. What is the correct IUPAC name of the compound?

1. 5-methyl hexanol
2. 2-methyl hexanol
3. 2-methylhex-3-enol
4. 4-methyl pent-2-enol

Answer: 4. 4-methyl pent-2-enol

Solution: —do—

Question 55. The IUPAC name of the compound is:

1. But-2-ene-2,3-diol
2. Pent-2-ene-2,3-diol
3. 2-methylbut-2-ene-2,3-diol
4. Hex-2-ene-2,3-diol

Answer: 2. Pent-2-ene-2,3-diol

Solution: Follow IUPAC rules.

Question 56. Which nomenclature in IUPAC is incorrect?

1. Pentyne-3
2. Pentyne-2
3. Hexyne-3
4. None of these

Answer: 1. Pentyne-3

Solution: CH₃ C = CCH₂ CH₃; It is always pentyne-2 and never pentyne-3.

Question 57. The IUPAC name of the compound CH₃ CONHBr is

1. 1-bromoacetate
2. Ethanoylbromide
3. N-Bromoethanamide
4. None of these

Answer: 3. N-Bromoethanamide

Solution: Follow IUPAC rules.

Question 58. The IUPAC name of the compound is:

1. 3-ethyl-4,4-dimethyl heptane
2. 1,1-diethyl-2,2-dimethyl pentane
3. 4,4-dimethyl-5,5-diethyl pentane
4. 5,5-diethyl-4, 4-dimethyl pentane

Answer: 1. 3-ethyl-4,4-dimethyl heptane

Solution: Follow IUPAC rules.

Question 59. The correct IUPAC name of the compound is:

1. 3-(1-ethyl propyl) hex-1-ene
2. 4-Ethyl-3-propyl hex-1-ene
3. 3-Ethyl-4-ethenyl heptane
4. 3-Ethyl-4-propyl hex-5-ene

Answer: 2. 4-Ethyl-3-propyl hex-1-ene

Solution: Follow IUPAC rules.

Question 60. The IUPAC name of the following compound is

1. 4-bromo-3-cynophenoal
2. 2-bromo-5-hydroxy benzonitrile
3. 2-cyano-4-hydroxybromobenzene
4. 6-bromo-3-hydroxy benzonitrile

Answer: 2. 2-bromo-5-hydroxy benzonitrile

Solution: The Cyano group has the highest priority therefore, parent name must be benzonitrile. Br occurs at 2- position, and hydroxyl at 3-position, hence the IUPAC name is 2-bromo-5-hydroxy benzonitrile.

Question 61. IUPAC name of the compound is

1. 2-chloromethyl-4-methyl-hexanal
2. 1-chloro-4-ethyl-2-pentanal
3. 1-chloro-4-methyl-2-hexanal
4. 1-chloro-2-aldo-4-methyl hexane

Answer: 1. 2-chloromethyl-4-methyl-hexanal

Solution: Follow IUPAC rules.

Question 62. Which one is not in the IUPAC system?

Answer: 2

Solution: It should be 4-ethyl-3-methyl heptane.

Question 63. The correct IUPAC name is

1. 1- cyclopropyl Cyclobutane
2. 1, 1-cyclobutane
3. 1- cyclobutane-1- cyclopropane
4. None of the above

Answer: 1. 1- cyclopropyl Cyclobutane

Solution: Follow IUPAC rules.

Question 64. The IUPAC name of the compound

1. 3, 3-dimethyl-1-hydroxy cyclohexane
2. 1, 1-dimethyl-3- hydroxy cyclohexane
3. 3, 3- dimethy-1- cyclohexanol
4. 1,1-dimethyl-3-cyclohexanol

Answer: 3. 3, 3- dimethyl-1- cyclohexanol

Solution: Carbon with – OH group is given C₁ thus it is 3, 3-dimethyl-1-cyclohexanol.

Question 65. The IUPAC name of the compound is

1. But-2-en-l-ol
2. l-hydroxy but-l-ene
3. 4-hydroxy butene-3
4. But-l-en-l-ol

Answer: 4. But-l-en-l-ol

Solution: Follow IUPAC rules.

Question 66. The name of (CH₃)₂ HC—O—CH₂—CH₂—CH₃ is:

1. Isopropyl propyl ether
2. Dipropyl ether
3. Di-isopropyl ether
4. Isopropyl propyl ketone

Answer: 1. Isopropyl propyl ether

Solution: Ether group (—O—) has propyl and isopropyl groups on its two sides.

Question 67. IUPAC name of, CH₃ CH(OH) CH₂ CH₂ COOH is:

1. 4-hydroxy pentanoic acid
2. 1-carboxy-3-butanoic acid
3. 1-carboxy-4-butanol
4. 4-carboxy-2-butanol

Answer: 1. 4-hydroxy pentanoic acid

Shortcut tricks for IUPAC nomenclature NEET with practice questions

Question 68. The prefix name of —SH group in IUPAC system is:

1. Mercapto
2. Thiol
3. Sulphide
4. None of these

Answer: 1. Mercapto

Solution: Follow IUPAC rules.

Question 69. The correct structure of 4-bromo-3-methyl-but-1-ene.

1. Br-CH=C(CH₃)₂
2. CH₂=CH-CH(CH₃)-CH₂ Br
3. CH₂=C(CH₃)CH₂ CH₂ Br
4. CH₃-C(CH₃)=CHCH₂-Br

Answer: 2. CH₂=CH-CH(CH₃)-CH₂ Br

Solution: Follow IUPAC rules.

Question 70. Which of the following represents neo-pentyl alcohol?

1. CH₃CH(CH₃)CH₂CH₂OH
2. (CH₃)₃C-CH₂OH
3. CH₃(CH₂)₃ OH
4. CH₃CH₂CH(OH)C₂H₅

Answer: 2. (CH₃)₃C-CH₂OH

Solution: (CH₃)₃C-CH₂OH is neo-pentyl alcohol.

Question 71. IUPAC name of the compound, ClCH₂ CH₂ COOH is:

1. 3-chloropropanoic acid
2. 2-chloropropanoic acid
3. 2-chloroethanoic acid
4. Chlorosuccinic acid

Answer: 1. 3-chloropropanoic acid

Solution: Follow IUPAC rules.

Question 72. Which of the following IUPAC names is correct?

1. 2-methyl-3-ethyl pentane
2. 2-ethyl-3-methyl pentane
3. 3-ethyl-2-methyl pentane
4. 3-methyl-2-ethyl pentane

Answer: 3. 3-ethyl-2-methyl pentane

Solution: -do-

Question 73. IUPAC name of, (C₂H₅)₂CHCH₂OH is:

1. 2-ethyl butanol-1
2. 2-methyl pentanol-1
3. 2-ethyl pentanol-1
4. 3-ethyl butanol-1

Answer: 1. 2-ethyl butanol-1

Solution: Follow IUPAC rules.

Question 74. 3-phenylpropanoid acid is IUPAC name of:

1. Mendaleic acid
2. Pyruvic acid
3. Succinic acid
4. Cinnamic acid

Answer: 4. Cinnamic acid

Solution: C₆ H₅—CH=CHCOOH is cinnamic acid.

Question 75. IUPAC name of the compound is:

1. 1,2,3-trieyanopropane
2. Propane-1,2,3-tricarbonitrile
3. 1,2,3-cyclopropane
4. Propane triarylamine

Answer: 2. Propane-1,2,3-tricarbonitrile

Solution: Follow IUPAC rules.

Question 76. IUPAC name of the compound is

1. 4-isopropyl, 6-methyl octane
2. 3-methyl, 5-(1-methyl ethyl) octane
3. 3-methyl, 5-isopropyl octane
4. 6-methyl, 4-(1-methyl ethyl) octane

Answer: 2. 3-methyl, 5-(1-methyl ethyl) octane

Solution: IUPAC name of compound.

Straight chain which contains a large number of side chains is taken as the parent chain and the counting starts from that side where the side chain is nearest.

Question 77. IUPAC name of the compound is:

1. 4-bromo-3-ethyl-1,4-pentadiene
2. 2-bromo-3-ethyl-1,4pentadiene
3. 2-bromo-3-ethyl-1-5-pentadiene
4. None of the above

Answer: 2. 2-bromo-3-ethyl-1,4pentadiene

Solution: The IUPAC name of this molecule is 2-bromo-3-ethyl-1, 4-pentadiene.

Question 78. IUPAC name of the compound is:

1. 4,5-dimethyl oct-4-ene
2. 3,4-dimethyl oct-5-ene
3. 4,5-dimethyl oct-5-ene
4. None of the above

Answer: 1. 4,5-dimethyl oct-4-ene

Solution: Follow IUPAC rules.

Question 79. The correct IUPAC name of the following compound is

1. 5, 6-dimethyl-8-methyl dec-6-ene
2. 6-butyl-5-ethyl-3-methyl oct-4-ene
3. 5, 6-diethyl-3-methyl dec-4-ene
4. 2, 4, 5-triethyl non-3-ene

Answer: 3. 5, 6-diethyl-3-methyl dec-4-ene

Question 80. Which of the following compounds has incorrect IUPAC nomenclature?

Answer: 4

Question 81. The IUPAC name of the compound is

1. 1,2,3-tricarboxylic-2,1-propane
2. 3-carboxy-3-hydroxy-1,5-pentanoic acid
3. 3-hydroxy-3-carboxy-1,5-pentanoic acid
4. None of the above

Answer: 2. 3-carboxy-3-hydroxy-1,5-pentanoic acid

Solution: Follow IUPAC rules.

Question 82. IUPAC name of is

1. Bicyclo (2,1,0) pentane
2. 1,2-cyclopropyl Cyclobutane
3. Cyclopentane (4,3) annulene
4. 1,2-methylene Cyclobutane

Answer: 1. Bicyclo (2,1,0) pentane

Solution: Follow IUPAC rules.

Question 83. The IUPAC name of neopentane is:

1. 2,2-dimethylpropane
2. 2-methylpropane
3. 2,2-dimethylbutane
4. 2-methyl butane

Answer: 1. 2,2-dimethylpropane

Solution: Follow IUPAC rules.

Question 84. The IUPAC name of compound shown below is

1. 2-bromo-6- chlorocyclohex-1-ene
2. 6-bromo-2-chlorocyclohexene
3. 3-bromo-1-chlorocyclohexene
4. 1-bromo-3-chlorocyclohexene

Answer: 3. 3-bromo-1-chlorocyclohexene

Solution:

Unsaturation (double bond) is given priority over halogen, then the lowest set of locants. So, the correct IUPAC name is 3-bromo-1-chlorocyclohexene.

NEET important nomenclature problems with step-by-step solutions

Question 85. The IUPAC name of 

1. 4-hydroxy-1-methylpentanal
2. 4-hydroxy-4-methyl pent-2-en-1-al
3. 2-hydroxy-4-methyl pent-2-en-5-al
4. 2-hydroxy-3-methyl pent-2-en-5-al

Answer: 2. 4-hydroxy-4-methyl pent-2-en-1-al

Solution: Follow IUPAC rules.

Question 86. IUPAC’s name of is 

1. 3-chlorobutanol
2. 3-chlorobutanaldehyde
3. 3-chlorobutanol
4. 2-chlorobutanol

Answer: 3. 3-chlorobutanol

Solution:

The order is priority is -CHO > -Cl

Question 87. The IUPAC name of is 

1. 2-methyl-3-butanone
2. 3-methyl-butan-2-one
3. 3-methyl butanone
4. None of these

Answer: 2. 3-methyl-butane-2-one

Solution: Follow IUPAC rules.

Question 88. The IUPAC name of compound is

1. 2-ethyl prop-2-en-1-ol
2. 2-hydroxymethylbutan -1-ol
3. 2-methylenebutan-1-ol
4. 2-ethyl-3-hydroxypropyl-1-ene

Answer: 1. 2-ethyl prop-2-en-1-ol

Solution:

Question 89. Which nomenclature is not according to the IUPAC system?

Answer: 3

Solution: CH₂=CH-CH₂-Br is allyl bromide. Its IUPAC name is 3-bromopropene or 3-bromoprop-1-ene. Because here double bond is a functional group while halogen is a substituent. Double bond is given more priority and hence numbering starts from left.

Question 90. Acetonitrile is

1. CH₃CN
2. CH₃COCN
3. C₂H₅CN
4. C₆H₅CN

Answer: 1. CH₃CN

Solution: CH₃ C=N is known as acetonitrile or methyl cyanide.

Question 91. Isobutyl chloride is:

1. CH₃CH₂CH₂CH₂Cl
2. (CH₃)₂CHCH₂ Cl
3. CH₃CH₂CHClCH₃
4. (CH₃)₃C-Cl

Answer: 2. (CH₃)₂CHCH₂ Cl

Solution: It should contain (CH₃)₂CH- group to be named as iso.

Question 92. The given compound in IUPAC is called as

1. Diacetone
2. Acetone amine
3. Diacetone amine
4. 4-amino-4-methyl pentane-2-one

Answer: 4. 4-amino-4-methyl pentane-2-one

Solution: Follow IUPAC rules.

Question 93. The IUPAC name of compound is

1. 1-choloro-2,3-epoxypropane
2. 3-chloro-1,2-epoxypropane
3. 1-chloroethoxymethane
4. None of the above

Answer: 2. 3-chloro-1,2-epoxypropane

Solution: Follow IUPAC rules.

Question 94. Neo-heptyl alcohol is correctly represented as:

Answer: 3

Solution: Follow IUPAC rules.

Question 95. IUPAC name of the compound is CH₃ CH₂ C(Br)=CH-Cl

1. 2-bromo-1-chloro butene-1
2. 1-chloro-2-bromo butene-1
3. 3-chloro-2-bromo butene-2
4. None of the above

Answer: 1. 2-bromo-1-chloro butene-1

Solution: Follow IUPAC rules.

Question 96. The IUPAC name of CH₃-CH₂-CHO is

1. Propanal-1
2. 2-methyl butanal
3. Butanal-1
4. Pentanal-1

Answer: 1. Propanal-1

Solution: IUPAC name of CH₃ CH₂ CHO is propan-1-al.

Question 97. The IUPAC name of is

1. 4-hydroxy-1-methylpentanal
2. 4-hydroxy-2-methylpentanal
3. 3-hydroxy-2-methylpentanal
4. 3-hydroxy-3-methylpentanal

Answer: 2. 4-hydroxy-2-methylpentanal

Solution: Follow IUPAC rules.

Question 98. Select the correct statement:

1. The prefixes are written before the name of compound
2. The suffixes are written after the name of compound
3. The IUPAC name of a compound is always written as one word
4. All of the above

Answer: 4. All of the above

Solution: These are the IUPAC rules.

Question 99. Pick out the correct statement from the following and choose the correct answer from the codes given below

1. Hexa-1, 5-diene is a conjugated diene
2. Prop-1, 2-diene is conjugated diene
3. Hexa-1, 3-diene is a conjugated diene
4. Buta-1, 3-diene is an isolated diene
5. Prop-1, 2-diene is a cumulative diene

 

1. 1, 2
2. 2, 3
3. 4, 5
4. 2, 5

Answer: 3. 4, 5

Solution: In conjugated diene alternate single and double bonds are present while in cumulative diene, double bonds are present at adjacent positions.

Hence, statements 3 and 5 are correct.

Question 100. The IUPAC name for

1. 1,1-dimethyl-1,2-butanediol
2. 2-methyl-2,4-pentanediol
3. 4-methyl-2,4-pentanediol
4. 1,3,3-dimethyl-1,3-propanediol

Answer: 2. 2-methyl-2,4-pentanediol

Solution: -do-

Question 101. Formulae of phenyl carbinol and chloral are respectively:

1. C₆ H₅.CH₂ CH₂ OH and CHCl₂ CHO
2. C₆ H₅ CH₂ OH and CCl₃ CHO
3. C₆ H₅ OH and CH₂ Cl.CHO
4. C₆ H₅ CHO and CHCl₂ CHO

Answer: 2. C₆ H₅ CH₂ OH and CCl₃ CHO

Solution: Carbinol is trivial name for HCH₂ OH. Thus, C₆ H₅ CH₂ OH is phenyl carbinol and chloral is CCl₃ CHO.

Question 102. The correct name for the following hydrocarbon is

1. Tricycle [4.1.0] heptane
2. Bicyclo [5.2.1] heptane
3. Bicyclo [4.1.0] heptane
4. Bicyclo [4.1.0] hexane

Answer: 3. Bicyclo [4.1.0] heptane

Solution:

This compound contains 7 carbon atoms, so the corresponding alkane is heptane. Two bridges contain 4 and 1 carbon atom respectively and one bridge does not contain any carbon atom. So, the name of the compound is Bicyclo (4,1,0) heptane.

Question 103. The IUPAC name of the compound is:

1. 5-chloro-hex-2-ene
2. 2-chloro-hex-5-ene
3. l-chloro-1-methyl-pent-3-ene
4. 5-chloro-5-methyl-pent-2-ene

Answer: 1. 5-chloro-hex-2-ene

Solution: First the longest continuous chain of carbon atoms is selected. Number the chain from the side containing senior functional group (i.e., the group placed above in the seniority table).

Question 104. The IUPAC name of the compound is:

1. 1,1-diethyl1-2, 2-dimethyl pentane
2. 4,4-dimethyl-5,5-diethyl pentane
3. 5, 5-diethyl-4,4-dimethyl pentane
4. 3-ethyl-4,4-dimethyl heptane

Answer: 4. 3-ethyl-4,4-dimethyl heptane

Solution: -do-

Question 105. 2, 3-dimethyl hexane contains _______ tertiary ____ secondary and ______ primary carbon atoms, respectively

1. 2, 2, 4
2. 2, 4, 3
3. 4, 3, 2
4. 3, 2, 4

Answer: 1. 2, 2, 4

Solution: The structure of 2, 3-dimethyl hexane is

So, the number of tertiary carbon atoms = 2

The number of secondary carbon atoms = 2

The number of primary carbon atoms = 4

Question 106. IUPAC name of following compound is:

1. 2-cyclohexyl butane
2. 2-phenylbutazone
3. 3-cyclohexyl butane
4. 3-phenylbutazone

Answer: 2. 2-phenylbutazone

Solution: Follow IUPAC rules.

Question 107. 2-methyl-2-butene will be represented as:

Answer: 4

Question 108. Pick out the alkane which differs from the other members of the group

1. 2,2-dimethyl propane
2. Pentane
3. 2-methyl butane
4. 2, 2-dimethyl butane

Answer: 4. 2, 2-dimethyl butane

Solution: 2, 2-dimethyl butane is 6-carbon hydrocarbon (C₆ H₁₄)

Question 109. In IUPAC suffix name of —COX is:

1. Oyl halide
2. Halo carbonyl
3. Carbamoyl
4. None of these

Answer: 1. Oyl halide

Solution: Follow IUPAC rules.

Question 110. IUPAC name of following compound is:

1. 3-methyl cyclo-1-buten-2-ol
2. 4-methyl cyclo-2-buten-1-ol
3. 4-methyl cyclo-1-buten-3-ol
4. 2-methyl cyclo-3-buten-1-ol

Answer: 2. 4-methyl cyclo-2-buten-1-ol

Solution: Follow IUPAC rules.

Question 111. The correct IUPAC name of the acid is

1. Z-3-ethyl-4-methyl hex-3-en-1-oic acid
2. Z-3-ethyl-4-methyl hexanoic acid
3. Z-3, 4-diethyl pent-3-en-1-oic acid
4. E-3-ethyl-4-methylhex-4-en-1-oic acid

Answer: 3. Z-3, 4-diethyl pent-3-en-1-oic acid

Solution:

[The configuration of this compound is E because bulkier groups are present opposite of the double bond.]

Question 112. The IUPAC name of aldehyde is

1. Prop-2-en-1-al
2. Propenyl aldehyde
3. But-2-en-1-al
4. Propenal

Answer: 1. Prop-2-en-1-al

Solution: CH2=CH-CHO (Prop -2-en-1-al)

Question 113. Write the IUPAC name of the below compound.

1. 3-methoxy butane
2. 2-methoxy butane
3. 3-methyl-3-methoxy propane
4. Butoxy methane

Answer: 2. 2-methoxy butane

Solution: According to the IUPAC system ethers are named as alkoxy alkanes. The larger alkyl group forms the parent chain while the lower alkyl group is taken with the ethereal oxygen and forms a part of the alkoxy group.

Question 114. IUPAC name of the compound is

1. 4-butyl-2,5-hexadien-l-al
2. 5-vinyloct-3-en-l-al
3. 5-vinyloct-5-en-8-al
4. 3-butyl-1,4-hexadien-6-al

Answer: 1. 4-butyl-2,5-hexadien-l-al

Solution: Follow IUPAC rules.

Question 115. The IUPAC name of the compound is

1. Ethoxy propane
2. 1, 1-dimethyl ether
3. 2-ethoxy zso-propane
4. 2-ethoxy propane

Answer: 4. 2-ethoxy propane

Solution:

The above compound is an ether and its name is written as alkoxy alkane. Oxy is attached to the lower group. Hence, the IUPAC name of the above compound is 2-ethoxy propane.

Question 116. The IUPAC name of the compound

1. Ethane nitrile
2. Methane isonitrile
3. Ethane isonitrile
4. None of these

Answer: 2. Methane isonitrile

Solution: CH₃NC is methaneisonitrile.

Question 117. The structural formula of methyl aminomethane is:

1. (CH₃)₂ CHNH₂
2. (CH₃)₃ N
3. (CH₃)₂ NH
4. CH₃ NH₂

Answer: 3. (CH₃)₂ NH

Solution: IUPAC name is N-methyl methanamine.

Question 118. The IUPAC name of CH₃-CCH(CH₃)₂ is

1. 4-methyl-2-pentyne
2. 4, 4-dimethyl-2-butyne
3. methyl isopropyl acetylene
4. 2-methyl-4-pentyne

Answer: 1. 4-methyl-2-pentyne

Solution: Follow IUPAC rules.

Question 119. Which one of the following is the correct formula for dichlorodiphenyltrichloroethane?

Answer: 1

Solution: Follow IUPAC rules.

Question 120. IUPAC name of (CH₃)₂N-C₂H₅ is:

1. Dimethyl ethyl amine
2. Dimethyl aminomethane
3. Dimethyl aminoethane
4. N, N-dimethylethanolamine

Answer: 4. N, N-dimethylethanolamine

Question 121. 3-methyl penta-1,3-diene is:

1. CH₂=CH(CH₂)₂CH₃
2. CH₂=CHCH(CH₃)CH₂CH₃
3. CH₃CH=C(CH₃)CH=CH₂
4. CH₃-CH=CH(CH₃)₂

Answer: 3. CH₃CH=C(CH₃)CH=CH₂

Solution: Follow IUPAC rules.

Question 122. The IUPAC name of the compound is

1. 2-iodo-3-chloro-4-pentanoic acid
2. 4-oxo-3-chloro-2-iodo Pentanoic acid
3. 4-carboxy-4,3-chloro-2-butanone
4. 3-chloro-2-iodo-4-oxo-pentanoic acid

Answer: 4. 3-chloro-2-iodo-4-oxo-pentanoic acid

Solution: Report prefixes in alphabetical order.

Question 123. The IUPAC name for CH₃COCH(CH₃)₂ is:

1. 4-methyl isopropyl ketone
2. 3-methyl-2-butanone
3. Isopropyl methyl ketone
4. 2-methyl-3-butanone

Answer: 2. 3-methyl-2-butanone

Question 124. Give the IUPAC name of the compound

1. 1,1,3-trimethyl cyclo hex-2-ene
2. 1,3,3-trimethyl cyclo hex-l-ene
3. 1,1,5-trimethyl cyclo hex-5-ene
4. 2,6,6-trimethyl cyclo hex-l-ene

Answer: 2. 1,3,3-trimethyl cyclo hex-l-ene

Solution: Follow IUPAC rules.

Question 125. The name of the compound is:

1. (2Z,4Z)-2, 4-hexadiene
2. (2Z-, 4E)-2, 4-hexadiene
3. (2E, 4Z)-2, 4-hexadiene
4. (4E, 4Z)-2, 4-hexadiene

Answer: 1. (2Z,4Z)-2, 4-hexadiene

Solution: The name of the compound is (2Z,4Z)-2, 4-hexadiene.

Question 126. The IUPAC name of the compound is

1. 2-amino-3-hydroxy propanoic acid
2. l-hydroxy-2-amino propan-3-oic acid
3. l-amino-2-hydroxy propanoic acid
4. 3-hydroxy-2-amino propanoic acid

Answer: 1. 2-amino-3-hydroxy propanoic acid

Solution: Follow IUPAC rules.

Question 127. What is the formula of tertiary butyl alcohol?

1. CH₃-CH(CH₃)-CH₂-OH
2. CH₃-(CH₂)₂OH
3. CH₃-CH(OH)-CH₂-CH₃

Answer: 4. CH₃-CH(OH)-CH2-CH₃

Solution:

is the formula of tertiary butyl alcohol as in it – OH group is attached to tertiary carbon.

Question 128. The IUPAC name of the compound is

1. 2-ethoxy pentane
2. 4-ethoxy pentane
3. Pentyl-ethyl ether
4. 2-pentoxy ethane

Answer: 1. 2-ethoxy pentane

Solution: Follow IUPAC rules.

Question 129. The IUPAC name of the compound is

1. 2-ethyl-3-methyl butanol chloride
2. 2,3-dimethyl pentanol chloride
3. 3,4-dimethyl pentanol chloride
4. l-chloro-l-oxo-2,3-dimethyl pentane

Answer: 2. 2,3-dimethyl pentanol chloride

Question 130. The IUPAC name of the compound is

1. 1,2,3-trihydrosypropane
2. 3-hydroxy pentane-l,5-diol
3. 1,2,3-hydroxy-propane
4. Propane-1,2,3-triol

Answer: 4. Propane-1,2,3-triol

Solution: Follow IUPAC rules.

Question 131. The IUPAC name of is

1. 2-methyl-3-bromohexanal
2. 3-bromo-2-methylbutanal
3. 2-bromo-3-bromobutanal
4. 3-bromo-2-methylpentanal

Answer: 4. 3-bromo-2-methylpentanal

Solution: Follow IUPAC rules.

Question 132. The IUPAC name of

1. 4-propoxy pentane
2. Pentyl-propyl ether
3. 2-propoxy pentane
4. 2-pentoxy propane

Answer: 3. 2-propoxy pentane

Solution: Follow IUPAC rules.

Question 133. The systematic (IUPAC) name of the compound with the following structural formula shall be

1. 1-ethyl-2-methyl cyclohexene
2. 2-methyl-l-ethyl cyclohexene
3. 3-ethyl-2-methyl cyclohexene
4. 4-ethyl-3-methyl cyclohexene

Answer: 4. 4-ethyl-3-methyl cyclohexene

Solution: Follow IUPAC rules.

Question 134. Pyridine is:

1. An aromatic compound and a primary base
2. A heterocyclic amino compound and a tertiary base
3. An aromatic amino compound forms salts
4. A cyano derivative of benzene and a secondary base

Answer: 2. A heterocyclic amino compound and a tertiary base

Solution: Pyridine is a heterocyclic compound having six carbon-membered ring formed by C and N atoms

Question 135. The IUPAC name of (CH₃)₃C-CH=CH₂ is

1. 1, 1, 1-trimethyl-2-propene
2. 3, 3, 3-trimethyl-2-propene
3. 2, 2-dimethyl-3-butene
4. 3, 3-dimethyl-1-butene

Answer: 4. 3, 3-dimethyl-1-butene

Solution:

IUPAC name=3, 3-dimethyl-l-butene.

Question 136. The name of the compound is:

1. 2-pentanone
2. Pentanone-2
3. Pentan-2-one
4. All are correct

Answer: 4. All are correct

Question 137. Write the IUPAC name of

1. 3-methyl pentane-3-ol
2. 3-hydroxy hexane
3. 3-hydroxy-3-methyl pentane
4. All of the above

Answer: 1. 3-methyl pentane-3-ol