Final answer:
To make 3-chloro-2,2-dimethylbutane the major product, the reaction conditions should favor an SN1 mechanism, typical for tertiary alcohols, by using HCl with ZnCl2 (Lucas reagent) and keeping reaction temperatures lower to suppress elimination reactions.
Step-by-step explanation:
To modify the reaction conditions to make 3-chloro-2,2-dimethylbutane the major product, one could consider altering the reaction mechanism. Typically, halogenation of alkanes can proceed via either the SN1 or SN2 mechanism, depending on the substrate and reaction conditions. For instance, if the starting material is t-butanol, treating it with hydrobromic acid (HBr) will result in a substitution reaction via an SN1 mechanism due to the tertiary nature of the alcohol.
For the formation of 3-chloro-2,2-dimethylbutane, since we are dealing with a tertiary alcohol, ensuring that the SN1 mechanism is favored will lead to the desired product. This can be achieved by using a reagent such as HCl in the presence of ZnCl2 (Lucas reagent), which promotes the formation of a stable tertiary carbocation intermediate and favors the substitution at the tertiary carbon atom. The SN1 pathway is typically promoted by weak nucleophiles in polar protic solvents at higher temperatures.
To suppress the competing elimination reactions, reaction temperature can be kept lower since elimination is favored at higher temperatures. Additionally, solvents that promote the SN1 mechanism, like polar protic solvents, can be chosen to favor the substitution over elimination. Moreover, the use of specific reagents that favor SN1 over SN2 by hindering the backside attack necessary for an SN2 mechanism can also be beneficial. Such adjustments to the reaction conditions are essential in optimizing the yield of 3-chloro-2,2-dimethylbutane.