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Organic Lab Reactions 295

Organic Lab Reactions 295 - the position assumed by an...

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290 THE AROMATIC PRIMARY AMINO GROUP DEAMINATION PROCEDURE AMINE 1. Unsubstituted amines and their homologs 2. Aminoethers 3. Nitroamines ^ 4. Halogenated amines 5. Aminocarboxylic acids 4 6. Aminophenols * See, however, footnotes on p. 285. 1. Hypophosphorous acid 1 Alkaline formaldehyde [ Preferred Stabilized diazonium salts *J Oxidation of hydrazines 1 TT , , c ,. j. -1 t Useful Sodium stanmte j Ethanol Poor 2. Hypophosphorous acid Alkaline formaldehyde Stabilized diazonium salts * 3. Hypophosphorous acid Ethanol Stabilized diazonium salts * Alkaline formaldehyde 4. Hypophosphorous acid Ethanol Oxidation of hydrazine Alkaline formaldehyde 5. Ethanol Preferred Preferred Fails 1 Preferred Useful Unpromising Alkaline formaldehyde 6. Stabilized diazonium salts ' Sometimes useful Unpromising Promising APPLICATIONS OF THE DEAMINATION REACTION The deamination reaction is of considerable value both in synthesis and proof of structure. Its utility is best demonstrated by a considera- tion of several specific examples. An amino group may be useful in a synthesis because of its effect on the position assumed
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Unformatted text preview: the position assumed by an incoming substituent. The free ann'no group and its acyl derivatives are strongly ortho-para orienting; conver-sion to the ammonium salt produces a meio-directing group.* Advan-tage is taken, therefore, of the directing influence of this group in syn-thesizing compounds otherwise difficult to secure. Thus, bromination of aniline gives symmetrical tribromoaniline, which may be deaminated to 1,3,5-tribromobenzene in an over-all yield of 65-72%. 29 This appears to be the only practical method of preparing 1,3,5-tribromobenzene. Similarly, 2-nitro-3'-bromobiphenyl is obtained from benzidine in good yield by utilizing the meto-orienting influence of the ammonium ion, the. ortho-oiientiag effect of the amino group, and finally deaminating. 62 * For an account of this subject see Sidgwick's "Organic Chemistry of Nitrogen," revised by Taylor and Baker, pp. 69-70, Oxford Press, 1937....
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