Question

Show reactions for preparing each of the following compounds by the Grignard method:

3-pentanol                                  

3-methyl-3-pentanol

Hexanoic acid

1-phenyl-1-propanol

Answer 1

Using grignards you could start out with 1-bromoethane, then add Mg in a polar solvent without H bonds, so diethyl ether is usually used. then you would have CH3CH2-+MgBr which is your grignard. now you would have to add propanal which is CH3CH2-CHO. the grignard attacks the carbonyl and after adding some acid you get the alcohol, and you have 3 pentanol.
to get 3-methyl-3-pentanol, do the same work up, except instead of adding propanal, add 2-butanone, then acid and you have your product. it is important to remember that you cannot have acidic protons in grignard reactions, so adding the acid should be the very last step, and it could just be H3O+.

Use benzaldehyde and EtMgBr. You need an aprotic solvent like ether to run the reaction and a little aqueous acid to hydrolize the MgBr salt. I would choose HCl. and be careful, Grignard reactions can get away from you if you are not careful.

exanoic acid (caproic acid), is the carboxylic acid derived from hexane with the general formula C₅H₁₁COOH. It is a colorless oily liquid with an odor that is fatty, cheesy, waxy, and like that of goats or other barnyard animals. It is a fatty acid found naturally in various animal fats and oils, and is one of the chemicals that give the decomposing fleshy seed coat of the ginkgo its characteristic unpleasant odor.^[3] It is also one of the components of vanilla. The primary use of hexanoic acid is in the manufacture of its esters for artificial flavors, and in the manufacture of hexyl derivatives, such as hexylphenols.