Chapter 5, Problem 40P

Interpretation Introduction

Interpretation:

Structural formula for the major product for alkyl bromide, when each of the given alcohols is reacted with hydrogen bromide, is to be drawn using the same format for alkyl bromide as the original given alcohol. IUPAC name for each alkyl bromide including its stereochemistry is to be given.

Concept introduction:

Secondary and tertiary alcohols react with hydrogen halides by the ${\text{S}}_{\text{N}}\text{1}$ mechanism that involves formation of a carbocation intermediate in the rate-determining step.

Primary alcohols and methanol react with hydrogen halides by the ${\text{S}}_{\text{N}}2$ mechanism in which the nucleophile attacks alkyloxonium ion and displaces a water molecule from the carbon atom.

There is a possibility of a formation of a racemic mixture to give a mixture of stereoisomers when optically active alcohols react with hydrogen halides in an ${\text{S}}_{\text{N}}\text{1}$ mechanism.

There is an inversion of configuration for the reaction of optically active alcohols with hydrogen halides in an ${\text{S}}_{\text{N}}2$ mechanism

The three dimensional spatial arrangement of substituents at a chirality center is called the absolute configuration.

The Cahn-Ingold-Prelog rule system ranks the substituents in the chirality center in the order of decreasing atomic number. Higher atomic number takes precedence over lower atomic number for the substituent.

In next step, molecule is oriented such that the bond to the lowest ranked substituent points away from the observer. Then check the path of sequence of decreasing priority. If the path of sequence of decreasing priority is clockwise then the configuration is R and if path of sequence of decreasing priority is anticlockwise, then the confirmation is S.