40E - Organic Chemistry (Mcmurry)

Question

The following Walden cycle has been carried out. Explain the results, and indicate where Walden inversion occurs.

Step-by-Step Solution

Answer

Inversion takes place in step 4. step4

                                            Walden Inversion

Walden inversion

It occurs in the reactions where the inversion of stereogenic carbon occurs.

Each step of the series to find inversion

1. In step 1, when alcohol reacts with the potassium metal potassium alkoxide. Hence, no CO bond broken means no inversion occurs
2. In step 2, the potassium alkoxide reacts with the alkyl halide to form ether 

Then again, no CO bond break. The alkyl group replaces only potassium means no inversion occurs.

 

Each step of the series to find inversion

3. In step3, alcohol reacts with tosyl chloride, the OH bond is broken, and Ts replace h. Hence, no CO on break means no inversion occurs

4. In step4 –the OTs group is displaced, and then the CO bond is broken, and ether formation occurs. Hence, the inversion occurs.

                                       Reaction showing Walden’s inversion