Q8-63 E Simmons鈥揝mith reaction of cycl... [FREE SOLUTION]

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Chapter 8: Q8-63 E (page 262)

Simmons鈥揝mith reaction of cyclohexene with diiodomethane gives asingle cyclopropane product, but the analogous reaction of cyclohexene with 1,1-diiodoethane gives (in low yield) a mixture of two isomeric methylcyclopropane products. What are the two products, and how do they differ?

Short Answer

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Answer

Enantiomers, have R and S configurations.

Step by step solution

Simmons–Smith reaction

In the Simmons鈥揝mith reaction, diiodomethane reacts with zinc鈥揷opper alloy to produce an intermediate I鈥擟H₂Zn鈥擨 compound. Iodomethylzinc iodide transfers a CH₂ unit to the alkene in a stereospecific manner. Iodomethylzinc iodide is known as the Simmons鈥揝mith reagent and it is a carbenoid.

Simmons鈥揝mith reaction is a chelotropic reaction in which an organozinc carbenoid reacts with an alkene or alkyne to form a cyclopropane.

Reaction interpretation

Simmons鈥揝mith reaction is a stereospecific reaction in which both hydrogens CH₂ are in the same plane.
When cyclohexene reacts with 1,1-diiodoethane, it gives a mixture of two isomeric methylcyclopropane products that are enantiomers. They are R and S configurations.
They are non-superimposable mirror images and rotate plane-polarized light in different directions.