Organic Lab Reactions 279

Organic Lab Reactions 279 - water. Thus,...

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274 THE AROMATIC PRIMARY AMINO GROUP are far from conclusive, but apparently there is little, if any, advantage in replacing ethanol by the higher aliphatic alcohols. Benzyl alcohol may be superior to ethanol in reducing diazonium salts, but this by no means has been clearly demonstrated. 63 - 66 Influence of Water, Catalysts, and Other Substances Water. In the main, smooth replacement of a diazo group does not depend upon perfectly anhydrous conditions. Many successful deamina- tions take place with alcohol containing as much as 15% of water and, in some instances, a still larger proportion. 14 - 28 - **• 21 - " Although general practice does not require rigid exclusion of moisture, the amount of' water should be limited to about 5-10%. 10 - 68 Certain diazonium salts, however, are unstable in the presence of
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Unformatted text preview: water. Thus, 2-methoxy-4,5-dinitroaniline when diazotized in sulfuric acid containing an equal volume of water gives, in addition to the ex-pected diazonium salt, a diazo oxide * (XVII). 69 Apparently the nitro group undergoes hydrolytic cleavage, a hydroxybenzenediazonium salt (XVI) being intermediate in the diazo oxide formation. NH 2 ,OCH 3 N2+HSO4-OCH3 NO 2 NOj N 2 +HSO 4-OCH 8 ,OCH 3 With 3,5-dinitro-4-methoxyaniline rapid and complete conversion to the diazo oxide occurs upon diazotization with sulfuric or hydrochloric acid. 69 * See p. 270. 67 Muller and Tiete, Ber., 74, 823 (1941). 68 Beeson, Am. Chem. J., 16, 235 (1894). M Meldola and Stephens, / . Chem. Soc, 87, 1202 (1905)....
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