Synthesis of α-Amino Acids
Phosphorus-Containing Compounds
Peptide bonds form by condensation reactions and can be cleaved hydrolytically.
Resonance of the peptide bond restricts motion about the C–N bond, which takes on partial
double-bond character.
Strong acid or base is needed to cleave a peptide bond.
Polypeptides are made up of multiple amino acids linked by peptide bonds. Proteins are large,
folded, functional polypeptides.
Biologically, amino acids are synthesized in many ways. In the lab, certain standardized
mechanisms are used.
The Strecker synthesis generates an amino acid from an aldehyde.
An aldehyde is mixed with ammonium chloride (NH 4 Cl) and potassium cyanide. The ammonia
attacks the carbonyl carbon, generating an imine. The imine is then attacked by the cyanide,
generating an aminonitrile.
The aminonitrile is hydrolyzed by two equivalents of water, generating an amino acid.
The Gabriel synthesis generates an amino acid from potassium phthalimide, diethyl
bromomalonate, and an alkyl halide.
Phthalimide attacks the diethyl bromomalonate, generating a phthalimidomalonic ester.
The phthalimidomalonic ester attacks an alkyl halide, adding an alkyl group to the ester.
The product is hydrolyzed, creating phthalic acid (with two carboxyl groups) and converting
the esters into carboxylic acids.
One carboxylic acid of the resulting 1,3-dicarbonyl is removed by decarboxylation.
Phosphorus is found in inorganic phosphate (Pi), a buffered mixture of hydrogen phosphate
and dihydrogen phosphate
Phosphorus is found in the backbone of DNA, which uses phosphodiester bonds. In forming
these bonds, a pyrophosphate (PPi, ) is released. Pyrophosphate can then be hydrolyzed
