Bromination of (E)-2-butenedioic acid gives

Options

A. (2R, 3S)-2, 3-dibromosuccinic acid
B. (2R, 3R)-2, 3-dibromosuccinic acid
C. a mixture of (2R, 3R) and (2S, 3S)-2,3-dibromosuccinic acid
D. (2S, 3S)-2,3-dibromosuccinic acid

Explanation

To solve the problem of what product is formed from the bromination of (E)-2-butenedioic acid, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Structure of (E)-2-butenedioic acid**:
- The structure of (E)-2-butenedioic acid (also known as fumaric acid) can be represented as:
\[ \text{HOOC-CH=CH-COOH} \]
- In this structure, the two carboxylic acid groups (COOH) are on opposite sides of the double bond, which is characteristic of the E configuration.

2. **Understand the Bromination Reaction**:
- Bromination involves the addition of bromine (Br2) across the double bond. The reaction can be represented as:
\[ \text{C=C} + \text{Br}_2 \rightarrow \text{Br-CH-CH-Br} \]
- This reaction proceeds through a cyclic bromonium ion intermediate.

3. **Mechanism of Bromination**:
- The Br2 molecule dissociates into Br+ and Br−. The Br+ attacks one of the carbons of the double bond, forming a bromonium ion.
- The Br− then attacks the more substituted carbon from the opposite side (backside attack), leading to anti-addition.

4. **Draw the Product**:
- After the bromination, the product will have bromine atoms added to the two carbons of the double bond. The resulting structure will be:
\[ \text{HOOC-CH(Br)-C(Br)-COOH} \]
- This product is known as 2,3-dibromosuccinic acid.

5. **Determine the Configuration**:
- The product will have two stereocenters at the carbons where bromine is added. The configurations can be determined by assigning priorities based on the Cahn-Ingold-Prelog rules.
- The resulting product will have one stereocenter with R configuration and the other with S configuration, leading to the final product being 2R, 3S-2,3-dibromosuccinic acid.

### Final Answer:
The product of the bromination of (E)-2-butenedioic acid is **2R, 3S-2,3-dibromosuccinic acid**.

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