Q. 13.18 - An Introduction to General, Organic, and Biological Chemistry

Question

Identify each of the following as D or L:

Step-by-Step Solution

Answer

(Part a) The structure is $L-$ Isomer

(Part b) The structure is  $L-$isomeric

 

(Part c) The structure is $D-$isomeric

Step 1 : Given information (Part a)

The structure is 

We have to find the isomer.

Step 2 : Explanation (Part a)

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 $OH\hspace{0.17em}$ 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 penultimate carbon has the hydroxy group on the left side, which means that this structure is the $L$ isomer.

Step 3 : Given infomation (b)

The structure is 

We have to find the isomer.

Step 4 : Explanation for (b)

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 $OH$ in the $L$ isomer of the penultimate carbon is on the right side, and in $D$ isomer is on the left side. In the Figure below, we can see examples of $D$ and $L$ isomers on glyceraldehyde.

b) In this example, the penultimate carbon has the hydroxy group on the left side, which means that this structure is the $L$ isomer.

Step 5 : Given information (c)

The structure is 

We have to find the isomer

Step 6: 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 $OH$ 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 penultimate carbon has the hydroxy group on the right side, which means that this structure is the D isomer.