Chapter 23, Problem 12P

The IUPAC rules permit the use of common names for a number of familiar phenols and aryl ethers. These common names are listed here along with their systematic names. Write the structure of each compound.

(a) $Vanillin\left(\text{4-hydroxy-3-methoxybenzaldehyde}\right)$: a component of vanilla bean oil, which contributes to its characteristic flavor

(b) $Thymol\left(\text{2-isopropyl-5-methylphenol}\right)$: obtained from oil of thyme

(c) $Carvacrol\left(\text{5-isopropyl-2-methylphenol}\right)$: present in oil of thyme and marjoram

(d) $Eugenol\left(\text{4-allyl-2-methoxyphenol}\right)$: obtained from oil of cloves

(e) $Gallicacid\left(\text{3,4,5-trihydroxybenzoic acid}\right)$: prepared by hydrolysis of tannins derived from plants

(f) $Salicylalcohol\left(o\text{-hydroxybenzyl alcohol}\right)$: obtained from bark of poplar and willow trees

Interpretation Introduction

Interpretation:

The structures of the given compounds are to be drawn.

Concept introduction:

The systematic naming of organic compound is done by using IUPAC nomenclature. The naming of an organic compound is done in such a way that the structure of the organic compound is correctly interpreted from its name.

In order to determine the structure of an organic compound from its name, first the root word in the name is identified. The suffixes like $\text{-ane, -ene, -yne, -ol, -al}$ in the name represent that the parent compound is an alkane, alkene, alkyne, alcohol and aldehyde respectively.

In the next step of structure identification of the organic compound from its name, the position, location and number of the substituents bonded to the carbon chain are determined.

Answer to Problem 12P

Solution:

a) The structure of $vanillin$ can be shown as follows.

b) The structure of $thymol$ can be shown as follows.

c) The structure of $carvacrol$ can be shown as follows.

d) The structure of $eugenol$ can be written as follows.

e) The structure of $gallicacid$ is shown as follows.

f) The structure of $salicylalcohol$ is shown as follows.

Explanation of Solution

a) The structure of $vanillin\left(\text{4-hydroxy-3-methoxybenzaldehyde}\right)$

The given compound is $vanillin$. Its IUPAC name is $\text{4-hydroxy-3-methoxybenzaldehyde}$. The root word in the name is benzaldehyde which indicates that the structure contains a benzene ring with an aldehyde functional group at first carbon atom. The functional groups that are attached to the longest chain are called substituents and they are written as prefixes in alphabetical order. The substituent present at the third carbon atom is methoxy group and that present at the fourth carbon atom is hydroxyl group. Therefore, the structural formula for the given aldehyde can be written as follows.

b) The structure of $thymol\left(\text{2-isopropyl-5-methylphenol}\right)$

The given compound is $thymol$. Its IUPAC name is $\text{2-isopropyl-5-methylphenol}$. The root word in the name of the compound is phenol. It indicates that the structure consists of a benzene ring with hydroxyl functional group at the first carbon atom. The substituent present at the second carbon atom is isopropyl group and that present at the fifth carbon atom is methyl group. Therefore, the structural formula for the given compound can be shown as follows.

c) The structure of $carvacrol\left(\text{5-isopropyl-2-methylphenol}\right)$

The given compound is $carvacrol$. Its IUPAC name is $\text{5-isopropyl-2-methylphenol}$. The root word ‘phenol’ in the name indicates that the structure contains a benzene ring with a hydroxyl functional group at first carbon atom. The isopropyl group is attached to the fifth carbon atom and methyl group is attached to the second carbon atom. Therefore, the structural formula for the given compound can be shown as follows.

d) The structure of $eugenol\left(\text{4-allyl-2-methoxyphenol}\right)$

The given compound is $eugenol$. Its IUPAC name is $\text{4-allyl-2-methoxyphenol}$. The root word is phenol, which indicates that the structure contains a benzene ring with a hydroxyl functional group at the first carbon atom. The substituent present at the second carbon atom is methoxy group and that present at the fourth carbon atom is allyl group. Therefore, the structural formula for the given compound can be written as follows.

e) The structure of $gallicacid\left(\text{3,4,5-trihydroxybenzoic acid}\right)$

The given compound is $gallicacid$. Its IUPAC name is $\text{3,4,5-trihydroxybenzoic acid}$. The root word in the name is benzoic acid which indicates that the structure contains a benzene ring with a carboxylic acid functional group at the first carbon atom. The three hydroxy groups are attached to the third, fourth and fifth carbon atom respectively. Therefore, the structural formula for the given compound can be shown as follows.

f) The structure of is $salicylalcohol\left(o\text{-hydroxybenzyl alcohol}\right)$

The given compound is $salicylalcohol$. Its IUPAC name is $o\text{-hydroxybenzyl alcohol}$. The name of the compound suggests that the compound is a benzyl alcohol with hydroxyl functional group at ortho position. Therefore, the structural formula for the given compound can be written as follows.