Concept explainers
Interpretation:
The synthesize of DL-leucine, DL-alanine, and DL-phenylalanine from potassium phthalimide and diethyl αa-bromomalonate.
Concept Introduction:
>Amino acids are synthesized by plants and animals. There are some amino acids which are not synthesized by the higher animals. These amino acids are then taken up by the animals from various other sources.
>There are two types of amino acid-syntheses, which are, from potassium phthalimide, and the Strecker synthesis. The potassium phthalimide type of synthesis uses diethyl αa-bromomalonate and SN2 reactions, and hydrolysis and decarboxylation occur in it.
>The potassium phthalimide method is a modification of the Gabriel synthesis of
Decarboxylation reaction is the reaction in which there is loss of a molecule of carbon dioxide from a compound.
>The reaction of an
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Organic Chemistry
- Tetrapeptide A is completely hydrolysed under acidic conditions to yield alanine, aspartic acid, isoleucine and valine. On neutralisation of the hydrolysate, an odour of ammonia is detected. The reaction of the tetrapeptide with phenylisothiocyanate, followed by mild hydrolysis yields no phenylthiohydantoin derivative. Incubation of A with carboxypeptidase A has no effect either. Explain...arrow_forwardThe peptide Proline-Serine-Alanine-Phenylalanine-Glutamine is present at pH 7. Draw the peptide and include stereochemistry.arrow_forwardGive the structure of compound A.arrow_forward
- Somatostatin is a tetradecapeptide of the hypothalamus that inhibits the release of pituitary growth hormone. Its amino acid sequence has been determined by a combination of Edman degradations and enzymic hydrolysis experiments. On the basis of the following data, deduce the primary structure of somatostatin: 1. Edman degradation gave PTH-Ala. 2. Selective hydrolysis gave peptides having the following indicated sequences: Phe-Trp Thr-Ser-Cys Lys-Thr-Phe Thr-Phe-Thr-Ser-Cys Asn-Phe-Phe-Trp-Lys Ala-Gly-Cys-Lys-Asn-Phe 3. Somatostatin has a disulfide bridge.arrow_forward15. The quantitative determination of glutamic acid can be carried out: A) Kjeldahl method B) Alkalimetrically (one carboxyl group) B) Alkalimetrically (for two carboxyl groups, linking the amino group with a formaldehyde solution) D) Argentometricallyarrow_forwardDraw three-dimensional representations of the following amino acids.(a) l-phenylalanine (b) l-histidine (c) d-serine (d) l-tryptophanDraw three-dimensional representations of the following amino acids.(a) l-phenylalanine (b) l-histidine (c) d-serine (d) l-tryptophanarrow_forward
- Show how you could us the acetamidomalonate method to prepare the followig amino acids (a)Leucine (b)Tryptophanarrow_forwardFor each amino acid listed, tell whether its influence on tertiary structure is largely through hydrophobic interactions,hydrogen bonding, formation of salt bridges, covalent bonding, or some combination of these effects.(a) Tyrosine (b) Cysteine(c) Asparagine (d) Lysine(e) Tryptophan (f) Alanine(g) Leucine (h) Methioninearrow_forwardWhat is the structure of below amino acid at its isoelectric point: (a) alanine;arrow_forward
- What will you do to detect the presence of protein in powdered casein? Briefly explain each process.arrow_forwardOutline the steps needed to synthesize the tetrapeptide Ala–Leu–Ile–Gly using the Merrifield technique.arrow_forwardThe reaction of ninhydrin with an -amino acid occurs in several steps (a) The first step is loss of water to give a triketone. Show the mechanism of the reaction and the structure of the triketone.(b) The second step is formation of an imine by reaction of the amino acid with the triketone. Show its structure. (c) The third step is a decarboxylation. Show the structure of the product and the mechanism of the decarboxylation reaction. (d) The fourth step is hydrolysis of an imine to yield an amine and an aldehyde. Show the structures of both products. (e) The final step is formation of the purple anion. Show the mechanism of the reactionarrow_forward