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Organic Lab Reactions 274

Organic Lab Reactions 274 - The literature oontains...

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INFLUENCE OF SUBSTTTUENTS 269 be obtained from 2,4-diamino-5-nitrotoluene (XI). Tetrazotization con- verted most of the diamine into alcohol-insoluble, amorphous material from which no definite product could be isolated; the alcohol-soluble portion gave a small quantity of 2-ethoxy-5-nitrotoluene (XII). CH 3 OC 2 H S O 2 N I ' 0 2 N NH 2 XI XII The effect of hydroxyl groups upon the reactions of diazpnium salts with ethyl alcohol appears not to be established. 26 ' 40 ' 41 -* Very recently it has been shown that treatment of the double salt of zinc chloride and p-hydroxybenzenediazonium chloride with ethyl alco- hol leads to phenol (38% yield) and p, p'-azophenol (ca. 50-55% yield). 41 N 2 +C1- OH H o / \—N=N—< x />OH It appears, therefore, that in this case the primary decomposition product is phenol and that by coupling with undecomposed diazonium salt it is converted into the azophenol. Addition of zinc oxide to the reaction mixture raises the yield of phenol to 60% while that of the azo compound falls to approximately 30%. Hydroxydiazonium salts derived from o- and p-aminophenols change * The literature oontains statements which lead to the Conclusion that the presence of a
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Unformatted text preview: * The literature oontains statements which lead to the Conclusion that the presence of a phenolic hydroxyl is generally conducive to replacement of the diazonium group_ by hydro-gen. (See references 40, 41.) The sole authority cited for this claim is a paper by Cameron published in 1898. (See reference 25.) However, careful scrutiny of this article reveals that the generalization is clearly not warranted by Cameron's results. He merely reports that the diazonium chlorides derived from 0-, m-, and p-aminophenol give phenol (yield unstated) and tar when decomposed with methyl or ethyl alcohol. Ethers could not be detected. Cameron himself states that "the'experiments with the diazophenols here recorded are to be regarded as indecisive." 40 Saunders, "The Aromatic Diazo-Compounds and Their Technical Applications," p. 145, Edward Arnold and Co., London, 1936. 41 Hodgson and Foster, J. Chem. Soc., 1940, 1150....
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