Question

Predict the major products (including stereochemistry) when trans-3-methylcyclohexanol reacts with thefollowingreagents.

(a) PBr₃

(b) SOCl₂

(c) Lucas reagent

(d) concentrated HBr

(e) TsCl/pyridine, then NaBr

Short answer

a.

b.

c.

d.

e.

Step-by-step solution

a. Reagent and Reaction

Phosphorous tribromide (PBr₃ ) used in a reaction to convert alcohols to bromides. These reagent is used when the alcohol is primary/secondary.

When trans-3-methylcyclohexanol reacts with phosphorous tribromide forms 3-methyl-1-bromocyclohexane.

b. Reagent and Reaction

b. Thionyl chloride (SOCl₂) used as chlorinating reagent to form aryl/alkyl chloride. When trans-3-methylcyclohexanol reacts with thionyl chloride to form 3-methyl-1-chlorocyclohexane.

c. Lucas Reagent and Reaction

Lucas reagent is used to differentiate/classify different types of alcohols (primary, secondary, tertiary).

When trans-3-methylcyclohexanol reacts with Lucas reagent form cis and trans-3-methyl-1-chlorocyclohexane.

d. Reagent and Reaction

HBr used in these reaction to form halo cyclohexane. It undergoes nucleophilic substitution reaction.

When trans-3-methylcyclohexanol reacts with concentrated form cis and trans-3-methyl-1-bromocyclohexane.

e. Reagent and Reaction

TsCl Used in these reaction as an activating group and pyridine neutralizes that generated by the reaction. Trans-3-methylcyclohexanol reacted with is reagent to form major product.

When trans-3-methylcyclohexanol reacted with and then with form 3-methyl-1-bromocyclohexane.