Interpretation:
The Strecker synthesis of DL-phenylalanine is to be outlined, and by preparing the starting
Concept introduction:
舧 Amino acids are organic compounds containing
舧 Strecker synthesis involves treating an aldehyde with ammonia and hydrogen cyanide to give an aminonitrile, which can be hydrolyzed to an αa-amino acid.
The general reaction is as:
舧 The Strecker synthesis involves formation of imine from phenyl acetaldehyde and ammonia, which on addition of hydrogen cyanide produces
舧 Acrolein and methanethiol on treating with a base gives
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Organic Chemistry
- -Amino acids can be prepared by the Strecker synthesis, a two-step process in which an aldehyde is treated with ammonium cyanide followed by hydrolysis of the amino nitrile intermediate with aqueous acid. Propose a mechanism for the reaction.arrow_forwardSynthesize octadecyl stearate using linoleic acid (18:2) (Given, stearic acid: 18:0) as the only starting material.arrow_forwardDraw the structure of the phenylthiohydantoin derivatives of(a) alanine. (b) tryptophan. (c) lysine. (d) proline.arrow_forward
- 26. (i) Why is the ester formation of alcohols and acid chlorides done in a weakly basic solution like pyrmidine? (ii) Why is this setup not viable for alcohols and carboxylic acids to form esters? pyrimidine deprotonates the alcohol; the alkoxide ion forms pyrimidine deprotonates the alcohol; the carboxylate ion forms pyrimidine deprotonates the tetrahedral intermediate; the alkoxide ion forms pyrimidine deprotonates the tetrahedral intermediate; the carboxylate ion formsarrow_forward(a) The isoelectric point (pI) of phenylalanine is pH 5.5. Draw the structure of the major form of phenylalanine at pHvalues of 1, 5.5, and 11.(b) The isoelectric point of histidine is pH 7.6. Draw the structures of the major forms of histidine at pH values of 1, 4,7.6, and 11. Explain why the nitrogen in the histidine ring is a weaker base than the a-amino group.(c) The isoelectric point of glutamic acid is pH 3.2. Draw the structures of the major forms of glutamic acid at pH valuesof 1, 3.2, 7, and 11. Explain why the side-chain carboxylic acid is a weaker acid than the acid group next to thea-carbon atomarrow_forwardShow how the Gabriel malonic ester synthesis could be used to prepare: (a) valine (b) phenylalanine (c) glutamic acid (d) leucinearrow_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_forwardHistamine is synthesized from one of the 20 protein-derived amino acids. Suggest which amino acid is its biochemical precursor and the type of organic reaction(s) involved in its biosynthesis (e.g., oxidation, reduction, decarboxylation, nucleophilic substitution). CH,CH,NH, H. Histaminearrow_forwardWrite out the steps needed to synthesize the following peptide using the Merrifield method.arrow_forward
- a) Explain why the acetamido group is an ortho, para-directing group. Why should it be less effective in activating the aromatic ring toward further substitution than an amino group? b) o-Nitroaniline is more soluble in ethanol than p-nitroaniline. Propose a flow scheme by which a pure sample of o-nitroaniline might be obtained from this reaction.arrow_forwardDraw three-dimensional representations of the following amino acids. Explain their structures. (a) L-phenylalanine (b) L-histidine (c) D-serine (d) L-tryptophanarrow_forwardSuggest a scheme you will follow to synthesise the dipeptide Ala-Glyarrow_forward