Mandelic acid, which has the formula C6H5CH(OH)COOH, can be isolated from bitter almonds (called mandel in German).

Question:

Mandelic acid, which has the formula C6H5CH(OH)COOH, can be isolated from bitter almonds (called mandel in German). It is sometimes used in medicine to treat urinary infections. Devise a two-step synthesis of mandelic acid from benzaldehyde, using the latter's cyanohydrin as an intermediate.