Which of the following statement is incorrect ?

Options

A. An `S_(N)1` reaction proceeds with inversion of configuration
B. An `S_(N)2` reaction proceeds with stereochemical inversion
C. An `S_(N)2` reaction follows second order kinetics
D. `E_(2)` reactions are generally stereoselective

Answer

To determine which statement is incorrect among the given options regarding SN1, SN2, and E2 reactions, let's analyze each statement step by step.

### Step 1: Analyze Option 1
**Statement:** An SN1 reaction proceeds with inversion of configuration.

**Explanation:**
- SN1 reactions are unimolecular nucleophilic substitution reactions.
- They involve two steps: first, the formation of a planar carbocation after the leaving group departs, and second, the nucleophile attacks the carbocation.
- Since the carbocation is planar, the nucleophile can attack from either side, leading to the formation of a racemic mixture (both enantiomers).
- Therefore, this statement is incorrect because SN1 does not lead to inversion of configuration.

### Step 2: Analyze Option 2
**Statement:** An SN2 reaction proceeds with stereochemical inversion.

**Explanation:**
- SN2 reactions are bimolecular nucleophilic substitution reactions.
- They occur in a single step where the nucleophile attacks the substrate from the opposite side of the leaving group.
- This backside attack results in inversion of configuration at the carbon center.
- Hence, this statement is correct.

### Step 3: Analyze Option 3
**Statement:** An SN2 reaction follows second-order kinetics.

**Explanation:**
- In SN2 reactions, the rate of reaction depends on the concentration of both the substrate and the nucleophile.
- This means that the reaction rate is proportional to the product of the concentrations of the two reactants, which defines second-order kinetics.
- Therefore, this statement is correct.

### Step 4: Analyze Option 4
**Statement:** E2 reactions are generally stereoselective.

**Explanation:**
- E2 reactions involve the elimination of a leaving group and a hydrogen atom from adjacent carbon atoms in a single concerted step.
- These reactions tend to favor the formation of the more stable alkene isomer (either E or Z), making them stereoselective.
- Thus, this statement is correct.

### Conclusion
After analyzing all the options, we find that:
- **Option 1 is incorrect**: An SN1 reaction does not proceed with inversion of configuration; it leads to a racemic mixture.

### Final Answer
The incorrect statement is **Option 1**: An SN1 reaction proceeds with inversion of configuration.

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