Question 3.15: Writing Structural Formulas from the Names of Organic Compou...
Writing Structural Formulas from the Names of Organic Compounds
Write the condensed structural formula for the organic compounds: (a) butane, (b) butanoic acid, (c) 1-chloropentane, (d) 1-hexanol.
Analyze
First, identify the number of carbon atoms in the chain, and then determine the type and position of the functional group, if any.
(a) The word stem but– indicates a structure with a four-carbon chain, and the suffix –ane indicates an alkane. No functional groups are indicated; hence, the condensed structural formula is CH_{3}{(CH_{2})}_{2}CH_{3}.
(b) The –oic ending indicates that the end carbon atom of the four-carbon chain is part of a carboxylic acid group. The condensed structural formula is CH_{3}{(CH_{2})}_{2}CO_{2}H.
(c) The prefix chloro– indicates the substitution of a chlorine atom for a H atom, and the 1- designates that it is on the first C atom of the carbon chain. The carbon chain is five C atoms long, as signified by the word stem pent-. The condensed structural formula is CH_{3}{(CH_{2})}_{3}CH_{2}Cl.
(d) The suffix –ol indicates the presence of a hydroxyl group in place of a H atom, and the 1- designates that it is on the first C atom of the carbon chain. The word stem hex– signifies that the carbon chain is six C atoms long. The condensed structural formula is CH_{3}{(CH_{2})}_{4}CH_{2}OH.
Assess
In summary, to obtain a structural formula from the name, we split the name into its component pieces: stem, prefix, and suffix. All three components provide information about the structure of the molecule.