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Organic Chemistry – Some Basic Principles and Techniques · Question 61

AIPMT 2005MCQMedium📈 Topic in 12% papers+4−1
1

Names of some compounds are given. Which one is not in IUPAC system?

  1. CH3-CH2-CH2- CH2CH3 |CH- CH3 |CH-CH2CH3 3-Methyl-4-ethylheptane
  2. CH3- OH |CH- CH3 |CH-CH3 3-Methyl-2-butanol
  3. CH3-CH2- CH2 \|C- CH3 |CH-CH3 2-Ethyl-3-methylbut-1-ene
  4. CH3-C C-CH(CH3)2 4-Methyl-2-pentyne

Answer

(1) CH3-CH2-CH2- CH2CH3 |CH- CH3 |CH-CH2CH3 3-Methyl-4-ethylheptane

Solution

As per NCERT, in IUPAC names the substituent prefixes are written in alphabetical order.

(1) Longest chain = 7 C; numbering from the right gives the lowest locants (3, 4): methyl at C-3, ethyl at C-4.

⇒ Correct name: 4-Ethyl-3-methylheptane (ethyl before methyl alphabetically); '3-Methyl-4-ethylheptane' breaks the alphabetical rule.

(2) 3-Methyl-2-butanol (3-methylbutan-2-ol) – correct.

(3) Longest chain containing C=C has 4 C; 2-Ethyl-3-methylbut-1-ene – correct.

(4) CH3-C C-CH(CH3)2: 4-Methyl-2-pentyne (4-methylpent-2-yne) – correct.

∴ The name in option (1) is not in the IUPAC system.

Answer: (1)

AIPMT 2005

Keep practising — Organic Chemistry – Some Basic Principles and Techniques

2

Which amongst the following is the most stable carbocation?

  1. CH3
  2. CH3 CH2
  3. CH3- CH3 | CH
  4. CH3- CH3 | CH3 | C
AIPMT 2005
3

Name of the compound given below is [figure]

  1. 4-ethyl-3-methyloctane
  2. 3-methyl-4-ethyloctane
  3. 2,3-diethylheptane
  4. 5-ethyl-6-methyloctane
AIPMT 2003
4

Which one of the following orders of acid strength is correct ?

  1. RCOOH > ROH > HOH > HC CH
  2. RCOOH > HOH > ROH > HC CH
  3. RCOOH > HOH > HC CH > ROH
  4. RCOOH > HC CH > HOH > ROH
AIPMT 2003
5

Which one of the following is a free-radical substitution reaction ?

  1. [figure]
  2. [figure]
  3. [figure]
  4. CH3CHO + HCN CH3CH(OH)CN
AIPMT 2003
6

IUPAC name of the following is CH2=CH-CH2-CH2-C CH

  1. 1-hexyne-5-ene
  2. 1,5-hexenyne
  3. 1-hexene-5-yne
  4. 1,5-hexynene
AIPMT 2002
7

CH2- O \|C-CH3 and CH2= O |C-CH3 are

  1. resonating structures
  2. tautomers
  3. geometrical isomers
  4. optical isomers
AIPMT 2002
8

The incorrect IUPAC name is

  1. CH3- O \|C- CH3 |CH-CH3 2-methyl-3-butanone
  2. CH3- CH3 |CH- CH2CH3 |CH-CH3 2,3-dimethylpentane
  3. CH3-C CCH(CH3)2 4-methyl-2-pentyne
  4. CH3 Cl |CH Br |CHCH3 2-bromo-3-chlorobutane
AIPMT 2001
9

The correct acidic order of the following is [figure]

  1. I > II > III
  2. III > I > II
  3. II > III > I
  4. I > III > II
AIPMT 2001
10

Which is maximum stable?

  1. 1-Butene
  2. cis-2-Butene
  3. trans-2-Butene
  4. All have same stability.
AIPMT 2000
11

Polarisation in acrolein can be described as

  1. + CH2=CH- + CHO
  2. - CH2=CH- + CHO
  3. - CH2=CH-CH + O
  4. + CH2=CH-CH - O
AIPMT 2000

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