ORGANIC TASK ANSWERS COURSE 1

UNIT 01 - NOMENCLATURE

Task 1a

Alkanes

1.

(i) 2,2-dimethylbutane

(ii) 2,3,5-trimethyl-4-propylheptane

(iii) 3,3-diethylhexane

(iv) 2,4-dimethylpentane

(v) 4-ethyl-2,2,5-trimethylheptane

2.

(i)

(ii)

(iii)

(iv)

(v)

Alkenes & Alkynes

3.

(i) But-1-ene

(ii) But-2-yne

(iii) 4-methylhex-2-yne

(iv) 4-methylpent-2-yne

(v) Buta-1,3-diene

4.

(i)

(ii)

(iii)

(iv)

(v)

Halogen Compounds

5.

(i) 1-iodopentane

(ii) 4-ethyl-3-methyl-nonanoyl bromide

(iii) Bromobenzene

(iv) (chloromethyl)benzene (benzyl chloride)

(v) 2-bromopropane

6.

(i)

(ii)

(iii)

(iv)

(v)

Alcohols

7.

(i) Pentan-3-ol

(ii) 2-methylbutan-2-ol

(iii) 3-bromobutan-2-ol

(iv) 3-phenylbutan-1-ol

(v) 3-nitrophenol

8.

(i)

(ii)

(iii)

(iv)

(v)

Aldehydes & Ketones

9.

(i) Butanal

(ii) 3-methylbutan-2-one

(iii) 2-methylpropanal

(iv) 3-methylbutan-2-one

(v) 3-phenylpropanal

10.

(i)

(ii)

(iii)

(iv)

(v)

Carboxylic Acids & Derivatives

11.

(i) Propanoic acid

(ii) 3-hydroxypentanoic acid

(iii) 2,2-dimethylpropanoic acid

(iv) 2-methylpropanoyl chloride

(v) 2-phenylpropanoic acid

12.

(i)

(ii)

(iii)

(iv)

(v)

Aromatics

13.

(i) (chloromethyl)benzene

(ii) 1,2-diethylbenzene

(iii) 4-bromophenol

(iv) 2-chlorotoluene

(v) 2-nitrobenzoic acid

14.

(i)

(ii)

(iii)

(iv)

(v)

Nitrogen Compounds

15.

(i) propanonitrile

(ii) N-methylaniline

(iii) 2-aminobenozic acid

(iv) N,N-diethylethanamine

(v) 3-phenylbutanonitrile

16.

(i)

(ii)

(iii)

(iv)

(v)

UNIT 02 - ISOMERISM

Task 2a

1.

2.

Hexane, 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane.

3.

Nonanes

2-methylnonane

3-methylnonane

4-methylnonane

5-methylnonane

Pentanes

2,4-dimethyl-3-(1-methylethyl)pentane

3,3-diethyl-2-methylpentane

3-ethyl-2,2,3-trimethylpentane

3-ethyl-2,2,4-trimethylpentane

3-ethyl-2,3,4-trimethylpentane

2,2,3,3,4-pentamethylpentane

2,2,3,4,4-pentamethylpentane

Task 2b

1.

2. IUPAC nomenclature insists that locants be kept as low as possible. As a result, butan-3-ol and butan-4-ol could (and should) be called butan-2-ol and butan-1-ol respectively, when counting from the other end of the chain.

3.

3 isomers; 2-mehylphenol, 3-methylphenol and 4-methylphenol.

4.

1,1-dibromobutane
1,2-dibromobutane
1,3-dibromobutane
1,4-dibromobutane
2,2-dibromobutane
2,3-dibromobutane
1,1-dibromo-2-methylpropane
1,2-dibromo-2-methylpropane
1,3-dibromo-2-methylpropane

Task 2c

1.

2.

Many answers possible here, but perhaps the simplest are pent-1-ene and cyclopentane;

3.

Many answers possible here, but perhaps the simplest are hexanal and hexan-2-one;

Task 2d

The cis isomer. Since a water molecule is eliminated by combining the -OH groups of two acid groups, they must be on the same side of the molecule to facilitate the dehydration reaction.

Task 2e

1.

E

Z

2.

There are no identical groups attached to each of the C atoms of the double bond, that can be grouped as being on the same side (cis) or different sides (trans).

3.

E

Z

Task 2f

1.(a)

(b)

Task 2g

1.

Least stable: Eclipsed with CH₃ groups aligned (#4), then

Eclipsed with CH₃ and H aligned (#2), then

Staggered with CH₃ groups adjacent to one another (gauche) (#1), then

Most stable: Staggered with CH₃ groups opposite one another (anti) (#3)

2.

Task 2h

1.

(a) 1,1-dichloropropane, 1,2-dichloropropane, 1,3-dichloropropane, 2,2-dichloropropane

(b) but-1-ene, but-2-ene, 2-methylpropene, cyclobutane, methylcyclopropane

(c) 1-bromobutane, 2-bromobutane, 2-bromo-2-methylpropane, 1-bromo-2-methylpropane

(d) 1-methyl-2,3-dinitro benzene, 1-methyl-2,4-dinitro benzene, 1-methyl-2,5-dinitro benzene, 1-methyl-2,6-dinitro benzene, 1-methyl-3,4-dinitro benzene, 1-methyl-3,5-dinitro benzene

2.

(a) Ethanoic acid, methyl methanoate, hydroxyethanal

(b) cis-Ethene-1,2-diol, trans-Ethene-1,2-diol, Ethene-1,1-diol

(c) Those in (a) are functional group isomers of those in (b)

3.

(a) cis-1,2-dibromoethene, trans-1,2-dibromoethene, 1,1-dibromoethene

(b) chloroethene (no isomers)

4.