Question

Which of the following are the starting materials for the Grignard’s synthesis of t-butanol?
A. $C{{H}_{3}}MgBr+C{{H}_{3}}COC{{H}_{3}}$
B. \[C{{H}_{3}}C{{H}_{2}}MgBr+C{{H}_{3}}COC{{H}_{3}}\]
C. \[C{{H}_{3}}MgBr+C{{H}_{3}}CHOHC{{H}_{3}}\]
D. \[C{{H}_{3}}MgBr+{{(C{{H}_{3}})}_{3}}CH\]

Answer 1

Hint: Grignard reagents are kept in the category of organometallic compounds. It is an organomagnesium compound represented by the chemical formula R-Mg-X where R refers to any alkyl or aryl group and X refers to halogen.

Complete answer: Butanol is the chemical compound represented by four carbon atoms chain having alcohol group with it and in t-butanol t stands for tertiary carbon atoms. Grignard reagents are commonly used for organic synthesis. Highly reactive compounds of Grignard reagents are supplied in flammable solvents. These reagents are generally prepared by the reaction between magnesium and organic halides, organic halides may be alkyl or aryl halides. It is necessary to ensure that no water is present during a reaction of Grignard reagents as it causes the reagent to decompose rapidly. Therefore the majority of Grignard reactions occur in solvents such as anhydrous diethyl ether or tetrahydrofuran because the oxygen in these solvents stabilizes the magnesium reagent.
t-butanol is prepared by the reaction of methyl magnesium bromide with acetone in presence of dry ether. Reaction can be shown as follows:
$C{{H}_{3}}MgBr+C{{H}_{3}}COC{{H}_{3}}\to C{{H}_{3}}C{{(C{{H}_{3}})}_{2}}OH+MgBrOH$

Hence we can say that option A is the correct answer.

Note: Normally the reaction used to the formation of Grignard reagents always requires the use of magnesium ribbon. The reason for this is that all magnesium is covered with a passivating film of magnesium oxide which prevents reactions to organic halide.