82614-48-0Relevant academic research and scientific papers
Substituent Effects on the Strength of C-C Bonds, 13. - Kinetic and Thermodynamic Stability of α-alkylated α-Amino Acid Esters - Energy of Stabilization of α-Amino-α-(ethoxycarbonyl)alkyl Radicals
Schulze, Rainer,Beckhaus, Hans-Dieter,Ruechardt, Christoph
, p. 1031 - 1038 (2007/10/02)
Thermolytic cleavage of 1a-c and 2a-c into radicals in solution are clean first-order processes.The activation parameters for C-C bond homolysis were determined.Compared with the corresponding data for hydrocarbons of equal strain a decrease of bond strength of 14.4 kcal/mol results by the combined interaction of the amino and the ethoxycarbonyl substituents.The heat of formation of 5 was determined by combustion calorimetry c(l) = -1207.75 +/- 0.20 kcal/mol> combined with the heat of vaporization (ΔH0v = 13.31 +/- 0.10 kcal/mol).Compared with the additive behaviour of group increments the resulting heat of formation (ΔH0f(g) = -112.02 +/- 0.24 kcal/mol> suggests a synergetic, geminal destabilization of Hsyn = 1.9 +/- 1.4 kcal/mol.Combination of the kinetic data of bond homolysis of 1a-c and 2a-c with the synergetic ground-state destabilization leads to a synergetic, capto-dative radical stabilization of Hsyn(rad) = 6.7 kcal/mol.Key Words: C-C Bond cleavage, kinetics of / Heat of formation / Radicals, stability of / Capto-dative effect / Geminal substituents, energetic interaction of
Thermolysis of Trialkylnitrosoureas: Formation of an Unusual Product
Singer, Sandra S.
, p. 3839 - 3844 (2007/10/02)
The thermolysis of four trialkylnitrosoureas, 1,1,3-trimethyl-1-nitrosourea (1), 3,3-diethyl-1-methyl-1-nitrosourea (2), 1-ethyl-3,3-dimethyl-1-nitrosourea (3), and 1,3,3-triethyl-1-nitrosourea (4), was carried out neat, in aprotic and aprotic solvents.When the thermolysis was run neat or in protic solvents, 4 gave as much as 70percent of N,N-diethylalanine ethylester (9).Ethyl N,N-diethylcarbamate (8) (about 10percent) was the only other product isolated.In protic solvent, however, 8 was the principal product.Neat thermolysis of 2 and 3 gave products analogues to those obtained from 4 but in much lower yields.Thermolysis of 1 did not give any product comparable to 9.Tetramethylurea was a major product from the thermolyses of 1 and 3.Decomposition of 3 was faster than any of the other three compounds, studied, but 3 did not give high yields of products.Addition of CuCl to the reaction mixture caused the reaction products to change dramatically.The appropriate dialkylnitrosamine and the denitrosated urea were then the major products.
