Organic Lab Reactions 285

Organic Lab Reactions 285 - In aqueous solution at 0 to +5,...

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280 THE AROMATIC PRIMARY AMINO GROUP Similarly, l-nitro-2-aminonaphthalene gives 1-chloronaphthalene in 69% yield and only a trace of 1-nitronaphthalene when diazotized in hydro- chloric acid solution and reduced with hypophosphorous acid. 83 Upon diazotization with sulfuric acid, however, a 61% yield of a-nitronaphtha- lene is obtained. 83 The same type of side reaction occurs when 2,5- diaminotriptycene (XX) is diazotized in hydrochloric acid solution and then reduced with hypophosphorous acid. 87 Cl xx Conversion of this diamine to triptycene has, however, been accom- plished in 40-45% yield by diazotizing with sulfuric acid; * l-bromo-2,5- diaminotriptycene (XXI) has also been deaminated by this procedure. 83 NH 2 The successful deamination of l-mtro-2-aminonaphthalene, 2,5-diamino- triptycene (XX), and l-bromo-2,5-diaminotriptycene (XXI) suggests that 5-amino-8-nitroisoquinoline (XVIII) also could be deaminated to 8-nitroisoquinoline if the diazotization were carried out in sulfuric acid.
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Unformatted text preview: In aqueous solution at 0 to +5, exchange of nuclear bromine for chlorine (pp. 271-272) does not occur. Thus, the diazonium chloride of 2,4,6-tribromoaniline when treated with hypophosphorous acid gives 1,3,5-tribromobenzene in 70% yield, while the hypophosphorous acid reduction of the diazonium chloride derived from 2,4,6-tribromo-3-methylaniline is productive of the corresponding tribromotoluene in 91% yield. 88-13 The conversion of diazotized 2,4,6-trinitroaniline (picramide) to 1,3,5-trinitrobenzene in 60-65% yield, upon treatment with aqueous hypo-phosphorous acid, 83 ' f is of considerable interest inasmuch as this dia-zonium salt is immediately decomposed by ice water " 62 alone (p. 275). * This deamination is described in detail oh p. 297. t Described in detail on p. 296. 87 Bartlett, Ryan, and Cohen, J. Am. Chem. Soc., 64, 2649 (1942). 88 Oberst, M. S. thesis, State University of Iowa, 1928, p. 29....
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