Organic Lab Reactions 297

Organic Lab Reactions 297 - atives might best be achieved...

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292 THE AROMATIC PRIMARY AMINO GROUP Ready conversion of nitro compounds to amines further extends the applicability of the deamination process. For example, the nitro group may be introduced into an aromatic nucleus for the purpose of closing a position to other groups in subsequent steps of a synthetic sequence, and, finally, the nitro group is replaced by hydrogen. This blocking effect is utilized in the preparation of 2-chlororesorcinol, which cannot be obtained by direct chlorination of resorcinol. 137 COOH COOH COOH O 2 N- H O 2 N OH COOH HssN—' COOH Any radical that may be converted to an amino group is capable of replacement by hydrogen. In certain instances such an indirect pro- cedure may be of value. Since polynuclear phenols are transformed into amines by the Bucherer reaction, 138 it has recently been suggested that the preparation of condensed ring hydrocarbons from the hydroxyl deriv-
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Unformatted text preview: atives might best be achieved through the amines, rather than by the customary zinc dust fusion. 139 Deamination affords an excellent method of degrading an amine of indeterminate structure to a known compound or one having fewer possi-ble isomers. A large number of illustrations might be cited; the follow-ing are typical. 1. Upon heating p-toluidine with sulfur at 140 in the presence of" litharge, the so-called thio-p-to.luidine is formed. It was shown to be fo's-(2-amino-5-methylphenyl) sulfide by deamination and subsequent oxidation to the crystalline sulfone^ 140 137 MUligan and Hope, J. Am. Chem. Soc, 63, 544 (1941). 188 Drake, Org. Reactions, I, 105 (1942). 189 Private communication from Professor M. S. Newman of Ohio State University. ""Bogert and Mandelbaum, J. Am. Chem. Soc, 45, 3052 (1923)....
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