Question

Identify each of the following as D or L:

Short answer

(a) The structure is an a$D$-isomer

(b) The structure is a $D$isomer is

(c) The structure is $L$isomer

Step-by-step solution

Given information (a) 

The structure is

We have to find that the isomer.

Explanation for (a)

In this problem, we have to identify given structures as D or L.

The difference between $D$and $L$isomers is in the position of the -$OH$group in the penultimate carbon atom. The $OH$group in the $D$isomer of the penultimate carbon is on the right side, and in $L$isomer is on the left side. In the Figure below, we can see examples of $D$and $L$isomers on glyceraldehyde.

In this example the numbering starts from the top carbon atom (with the hydroxy group), which means that the penultimate carbon has the $OH$group on the right side, which means that this structure is a $D$isomer.

Given information (b)

The structure is

We have to find the isomer

Explanation for (b) 

In this problem, we have to identify given structures as $L$or $D$.

The difference between $L$and $D$isomers is in the position of the $-OH$group in the penultimate carbon atom. The $OH$in the $D$isomer of the penultimate carbon is on the right side, and in $L$isomer is on the left side. In the Figure below, we can see examples of $D$and $L$isomers on glyceraldehyde.

In this example, the $OH$group is on the right side, which means that this structure is a $D$isomer.

Given information (c)

The structure is

We have to find the isomer.

Explanation for (c)

In this problem, we have to identify given structures as $D$or $L$.

The difference between $L$and $D$isomers is in the position of the - $OH$group in the penultimate carbon atom. The $OH$group in the $D$isomer of the penultimate carbon is on the right side, and in $L$isomer is on the left side. In the Figure below, we can see examples of $D$and $L$isomers on glyceraldehyde.

In this example, the $OH$group is on the left side, which means that this structure is a $L$isomer.