Answer:
SOCl2, Mg, CH3CHO, H3O^+
Step-by-step explanation:
The reaction of the 2,2-dimethylpropan-1-ol with SOCl2 converts the alcohol to an alkyl halide. This now reacts with Mg metal to yield a Grignard reagent.
The Grignard reagent reacts with CH3CHO and acid to yield 4,4-dimethylpentan-2-ol as shown in the image attached to this answer.