Question

Write structures for the following compounds.(a) 3-ethyl-4-methylhexane (b) 3-ethyl-5-isobutyl-3-methylnonane(c) 4-tert-butyl-2-methylheptane (d) 5-isopropyl-3,3,4-trimethyloctane

Answer 1

Answer:

Find attached answer to this question.

Explanation:

a. 4-Isopropyloctane has a chain of eight carbons, with an isopropyl group on the fourth carbon.

5-tert-Butyldecane has a chain of ten carbons, with a tert-butyl group on the fifth.

CH3

4-isopropyloctane

CHCH3 CH3

CH3 CH3CH2CH2CH2CH2CH2 CH

5-tert-butyldecane

CH3 CH3CH2CH2CH2CH2CH2CH2CH2 CH

CCH3 CH3

3-3 Nomenclature of Alkanes 93

di- means 2 tetra- means 4 hexa- means 6

tri- means 3 penta- means 5 hepta- means 7

b. Using this rule, we can construct names for some complicated structures. Let\u2019s fin-

ish naming the heptane on p. 90, shown here in the margin. This compound has an ethyl

group on C3 and three methyl groups on C2, C4, and C5. List the ethyl group alphabeti-

cally before the methyl groups, and give each of the four substituents a location number.

Problem-solving Hint

When substituents are alphabetized,

iso- is used as part of the alkyl group

name, but the hyphenated prefixes

are not. Thus, isobutyl is alphabetized

with i, but n-butyl, tert-butyl, and sec-

butyl are alphabetized with b. The

number prefixes di-, tri-, tetra-, etc.

are ignored in alphabetizing.

CH3 CH

2-bromobutane

Br

CH2CH3 CH3 CH

3-chloro-2-methylpentane

CH3 Cl

CH CH2CH3 CH3 CH

1,2-difluoropropane

F

CH2F

c. CH2CH(CH3)2CH2CH3

CH CHCH2 CH2 CH2CH3 CH3

S O LV E D P R O B L E M 3-2

Give a systematic (IUPAC) name for the following compound.

SOLUTION

The longest carbon chain contains eight carbon atoms, so this compound is named as an octane.

Numbering from left to right gives the first branch on C2; numbering from right to left gives

the first branch on C3, so we number from left to right.

CH CH2

CH3

CH CH CH2CH3

CH CH3

CH3

CH3

CH3

3-ethyl-2,4,5-trimethylheptane

7

65

4 3

2

1

CH3

CH3

CH3 CH3

CH3

CH3

CH3

CH

CH CH CH

CH2CH3

CH2

C

d. CH3 CH3

CH3

CH2 CH2 CH2 CH2 CH2

CH2

CH

CH3 CH3CH

CH

CH3 CH

Br CH2CH3

CH CH3(b)

CH3CH2

CH2CHCH3 CH3

Answer 2

Answer:

Here's what I get  

Explanation:

(a) 3-Ethyl-4-methylhexane

The main chain is eight carbons long, with an ethyl group at C-3 and a methyl group at C-4

(b) 3-Ethyl-5-isobutyl-3-methylnonane

The main chain is nine carbons long, with an ethyl group and a methyl group on C-3 and an isobutyl group on C-5.

Note that the name isobutyl is acceptable in general use, but the preferred IUPAC name (PIN) for the group is now (since 2013) "2-methylpropan-2-yl".

The PIN for your compound is 3-ethyl-3-methyl-5-(2-methyl propan-2-yl)nonane.

(c) 4-tert-butyl-2-methylheptane

The main chain is seven carbons long, with a tert-butyl group at C-4 and a methyl group at C-2.

For some reason, the IUPAC has retained the name tert-butyl for the group, so the name you give is the PIN.

The prefix "tert" is written in italics.

(d) 5-isopropyl-3,3,4-trimethyloctane

The main chain is eight carbon atoms long, with two methyl groups on C-3 and one on C-4, and an isopropyl group on C-5.

The PIN for an isopropyl group is now "propan-2-yl", so the IUPAC name for your compound is 3,3,4-trimethyl-5-(propan-2-yl)octane.