Question

Give condensed and bond line structural formulas and identify the functional group(s) present, if any, for, 

1. 2,2,4-Trimethylpentane, 
2. 2-Hydroxy-1,2,3-propanetricarboxylic acid, 
3.  Hexanedial.

Answer 1

1. 2,2,4-Trimethylpentane

Condensed structural formula:

\[ \text{CH}_3\text{-C}(\text{CH}_3)_2\text{-CH}_2\text{-CH}(\text{CH}_3)\text{-CH}_3 \]

Bond-line (skeletal) description:

Five-carbon main chain (pentane) drawn as a zig-zag line; two methyl branches at C-2 and one methyl branch at C-4.

Functional group(s):

Saturated hydrocarbon (alkane) only; no other functional group.

2. 2-Hydroxy-1,2,3-propanetricarboxylic acid

Condensed structural formula:

Central three-carbon skeleton: \(\text{HOOC-CH(OH)-C H_2-COOH}\) with an additional \(\text{-COOH}\) on C-1:
\[ \text{HOOC-CH(OH)-C(OH)(COOH)-CH}_2\text{COOH} \] or more clearly as the usual form (citric acid): \[ \text{HOOC-CH}_2\text{-C(OH)(COOH)-CH}_2\text{COOH} \]

Bond-line (skeletal) description:

Three-carbon chain; the middle carbon bears one hydroxyl group and one carboxyl group; the terminal carbons each bear one carboxyl group.

Functional group(s):

Carboxylic acid (\(-\text{COOH}\), three groups) and alcohol (\(-\text{OH}\), one group).

3. Hexanedial

Condensed structural formula:

\[ \text{OHC-CH}_2\text{-CH}_2\text{-CH}_2\text{-CH}_2\text{-CHO} \] or \[ (\text{OHC})(\text{CH}_2)_4(\text{CHO}) \]

Bond-line (skeletal) description:

Straight six-carbon chain; each terminal carbon is part of an aldehyde group (\(-\text{CHO}\)).

Functional group(s):

Two aldehyde groups (\(-\text{CHO}\)); the compound is a dialdehyde.