12. Alcohols, Ethers, Epoxides and Thiols

When 3-methyl-2-butanol is heated with concentrated HBr, a rearranged product is obtained. When 2-methyl-1-propanol reacts under the same conditions, a rearranged product is not obtained. Explain.

Explain the products observed in the following reaction of an alcohol with the Lucas reagent.

Show how you would use a simple chemical test to distinguish between the following pairs of compounds. Tell what you would observe with each compound.

(d) allyl alcohol and propan-1-ol

(e) butan-2-one and tert-butyl alcohol

Neopentyl alcohol, (CH₃)₃CCH₂OH, reacts with concentrated HBr to give 2-bromo-2-methylbutane, a rearranged product. Propose a mechanism for the formation of this product.

The reaction of tert-butyl alcohol with concentrated HCl goes by the S_N1 mechanism. Write a mechanism for this reaction.

Suggest a mechanism for the following reactions.

(b) Substitution :

Predict the product of the following reactions.

(a)

Predict the product of the following reactions.

(a)

Triphenylphosphine and iodine can be used to convert alcohols to iodoalkanes. Suggest a mechanism for this reaction. [Triphenylphosphine first acts as a nucleophile in this reaction.]

Suggest the appropriate reagents to carry out the following transformations.

(a)

Another method for converting alcohols to chloroalkanes makes use of chlorotrimethylsilane (TMSCl) and DMSO. Suggest a mechanism for this reaction to form (a) a 1° chloroalkane and (b) a 3° chloroalkane. [The reaction begins by the reaction of DMSO and TMSCl and is analogous to the Swern oxidation.]

Predict the product of the following reactions.

(b)

Predict the product of the following reactions.

(c)

Predict the product(s) that would result when molecules (a)–(p) are allowed to react under the following conditions: (vii) HCl; (viii) HBr. If no reaction occurs, write 'no reaction.'  

(a)

Predict the product of the following reactions.

(b)