In ____, an aldehyde is mixed with potassium cyanide and ammoniu…

In Strecker synthesis, an aldehyde is mixed with potassium cyanide and ammonium chloride.

Strecker Pathways:

#1 - If ammonia is added first, you get an imine as intermediate which then reacts with cyanide, thru nucleophilic addition, to form α-amino nitrile.

#2 - If cyanide is added first, you get a cyanohydrin (aka hydroxynitrile) as the intermediate which then reacts with ammonia, thru nucleophilic substitution, to form α-amino nitrile.

Note: In Strecker synthesis, first an aminonitrile is generate from an aldehyde or ketone. Secondly, hydrolysis of the aminonitrile results in formation of an amino acid.

Note: The starting material for the Strecker synthesis is a planar carbonyl-containing compound; therefore, the product of this pathway is a racemic mixture. The incoming nucleophiles are equally able to attack from either side of the carbonyl; thus, both L- and D-amino acids can be generated through this process.

Note: As seen below, the final product has the classic amino acid groups. Amino acid is generated from phthalimide (nucleophile) and diethyl bromomalonate, using two SN2 reactions, hydrolysis, and decarboxylation.

Question: What are the two ways we can organically synthesize amino acids?

1. Strecker Synthesis (Strecker uses Cyanide)

2. Gabriel Synthesis (Gabriel uses Rings)

Extra Note: The product of both the Strecker and the Gabriel synthesis pathways is a racemic mixture; both L- and D- amino acids are generated.

Khan Academy Link

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