The total number of monohalogenated organic products in the following (including stereoisomers) reaction is ______.
`A" "overset((i)H_(2)//Ni//Delta)underset((ii)X_(2)//Delta)rarr`
(Simplect optically active alkene)

Explanation

To determine the total number of monohalogenated organic products (including stereoisomers) from the given reaction, we will follow these steps:

### Step 1: Identify the Alkene
The starting material is a simple optically active alkene. Let's consider the smallest optically active alkene, which can be represented as CH3-CH=CH2 (propene).

### Step 2: Hydrogenation of the Alkene
In the first step, hydrogenation occurs in the presence of a nickel catalyst. This process adds hydrogen across the double bond, converting the alkene into an alkane. The product of hydrogenation of propene is butane (CH3-CH2-CH2-CH3).

### Step 3: Chlorination of the Alkane
Next, we perform chlorination (substitution reaction) using chlorine (Cl2) in the presence of sunlight. This reaction replaces one hydrogen atom with a chlorine atom.

### Step 4: Identify Possible Substitution Sites
In butane, we have:
- 2 primary carbons (CH3)
- 2 secondary carbons (CH2)
- 1 tertiary carbon (CH)

### Step 5: Count the Monohalogenated Products
1. **Primary Substitution**:
- Replacing a hydrogen on a primary carbon (CH3):
- Product 1: CH2Cl-CH2-CH2-CH3 (1-chlorobutane)
- Product 2: CH3-CH2-CH2-CH2Cl (2-chlorobutane)

2. **Secondary Substitution**:
- Replacing a hydrogen on a secondary carbon (CH2):
- Product 3: CH3-CHCl-CH2-CH3 (3-chlorobutane)

3. **Tertiary Substitution**:
- Replacing a hydrogen on a tertiary carbon (CH):
- Product 4: CH3-CH2-CHCl-CH3 (2-chlorobutane)

### Step 6: Identify Chiral Centers and Stereoisomers
- **Product 1 (1-chlorobutane)**: No chiral centers, 1 isomer.
- **Product 2 (2-chlorobutane)**: One chiral center (2 different groups), gives 2 stereoisomers.
- **Product 3 (3-chlorobutane)**: One chiral center (2 different groups), gives 2 stereoisomers.
- **Product 4 (2-chlorobutane)**: No chiral centers, 1 isomer.

### Step 7: Total Count of Isomers
- From Product 1: 1 isomer
- From Product 2: 2 stereoisomers
- From Product 3: 2 stereoisomers
- From Product 4: 1 isomer

### Final Calculation
Total = 1 + 2 + 2 + 1 = 6 monohalogenated products.

### Conclusion
The total number of monohalogenated organic products (including stereoisomers) is **6**.

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