The decomposition of nitrourea in aqueous solution

Boopsingh, Barbara; Briody, J. M.

doi:10.1039/p29720001487

Cited by 2 publications

(6 citation statements)

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“…6. In fact the rates measured in basic buffers 15 and those in dilute sulfuric acid 14 are contiguous, as Fig. 6 demonstrates, so it is not fanciful to propose hydroxide catalysis in dilute sulfuric acid solutions, and the Scheme 9 proposal for 2 is thus supported.…”

Section: Discussionmentioning

confidence: 90%

“…(In this and some other cases discussed here, the firstformed nitramide and alkylnitramine decomposition products 15 The lines refer to the different regions separately, the left one to the acid-catalysed process and the right two to the base-catalysed one; the latter two cross at the pK a of nitrourea in the buffer media used. 15 were occasionally identified by isolation and analysis, 10 as well as by decomposition rate. )…”

Section: Discussionmentioning

confidence: 91%

“…The reaction of nitrourea 5 in basic media has been studied by Boopsingh and Briody, 15 and the mechanism that they give is in Scheme 10. This is rather different from Scheme 9; removing the N-H in 2 does not achieve anything, but in 5 the highly favourable cyclic process involving the other NH 2 leads to ready Although this is rather different from the strong-acid mechanism proposed for 1-3, the parameters for it (given in Table 2) are quite similar, except for the slope m*m ‡ .…”

Section: Discussionmentioning

confidence: 99%

“…error of ±0.079. The excess acidity slope was used to define an acidity function (pH scale) applicable only to 5, 28 and activation parameters 14, 15 were used to correct a tiny temperature difference between this study and that of Boopsingh and Briody 15 in buffer media. The two studies were then combined to give the extended pH-rate profile given as Fig.…”

Section: Nitroureamentioning

confidence: 99%

“…8 N-Nitrosoamides hydrolyse via S N 2 displacement of the N-conjugate acid. 9 The work in this paper concerns a variety of Scheme 1 N-nitroamides, analysing available rate constants as a function of acid concentration and temperature for some N-nitrobenzenesulfonamides 1, 10,11 N-nitrobenzamides 2 12 and Nmethyl-N-nitrobenzamides 3, 13 N-nitroacetamide 4, 13 nitrourea 5, 14, 15 and also N,N-dinitromethylamine 6 for comparison; 16 Kuznetsov's group also studied some N-methyl-and other N-alkyl-N-nitrobenzenesulfonamides 17 but there are no rate constants given in that paper.…”

Section: Introductionmentioning

confidence: 99%

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The mechanisms of the hydrolyses of N-nitrobenzenesulfonamides, N-nitrobenzamides and some other N-nitro amides in aqueous sulfuric acid 1

Cox¹

1997

J. Chem. Soc., Perkin Trans. 2

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The mechanisms of the hydrolysis reactions of some N-nitrobenzenesulfonamides (YC 6 H 4 SO 2 NHNO 2 ), N-nitrobenzamides (YC 6 H 4 CONHNO 2 ) and N-methyl-N-nitrobenzamides (YC 6 H 4 CON(CH 3 )NO 2 ) have been determined in aqueous sulfuric acid using the excess acidity method. Also studied were N-methyl-Nnitroacetamide and nitrourea, with N,N-dinitromethylamine for comparison. N-Nitrobenzenesulfonamides give either YC 6 H 4 SO 2 ϩ and NH 2 NO 2 (electron-donating Y) or YC 6 H 4 SO 2 NH 2 and NO 2 ϩ (electron-withdrawing Y) in A1 processes; the change in product is reflected in the different ϩ values found for the two modes of cleavage. N-Nitrobenzamides behave similarly in strong acid, with an A1 reaction following presumed O-protonation, but in more moderate acid they exhibit a neutral watercatalysed hydrolysis mechanism, and in dilute acid the parent N-nitrobenzamides actually show hydroxide catalysis. N-Methyl-N-nitroacetamide shows only the neutral water-catalysed process. Nitrourea has an A1 acid-catalysed hydrolysis reaction in acid, analogous to the known B1 mechanism in base (also visible in dilute sulfuric acid), but has no water reaction; the pH-rate profile for the hydrolysis of this substance is here extended into the non-ideal acid region. N,N-Dinitromethylamine loses NO 2 ϩ in an A1 process following initial nitro-group protonation, giving N-nitromethylamine which is identifiable by its known hydrolysis rate. Activation parameters, m*m ‡ slopes and ϩ values given by the excess acidity analysis are shown to be compatible with the postulated mechanisms.

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Section: Discussionmentioning

confidence: 90%

Section: Discussionmentioning

confidence: 91%

Section: Discussionmentioning

confidence: 99%

Section: Nitroureamentioning

confidence: 99%