Diazopropane decomposition

Some examples of carbene dimer formation resulting from diazoalkane decomposition on transition-metal surfaces have been reported. Diazomethane is decomposed to give ethylene and N2 upon passage over a C0O/M0O3 catalyst as well as on Ni, Pd, Fe, Co, Ru and Cu surfaces 367). Similarly, 2-diazopropane is readily decomposed on Raney nickel 368). At room temperature, propene and N2 were the only detectable products, but above 50 °C, the carbene dimer 2,3-dimethyl-2-butene started to appear which reached its maximum yield at 100 °C, where approximately 40 % of the carbene fragments dimerized. It is assumed 367,368), that surface carbenes are formed as intermediates from both diazomethane and 2-diazopropane which either dimerize or desorb by migration of a P-hydrogren, if available (Scheme 40). 

Low-molecular-weight diazoalkanes are prepared by three general methods, all of which involve the basic decomposition of an N-nitroso compound. The first is concerned with the alkaline degradation of an N-nitroso-N-alkylurethane (equation 1). Thus, the synthesis of diazoethane and 1-diazopropane is accomplished in 75% and 57% yields, respectively, by the rapid addition of the corresponding nitrosourethane to a solution of potassium hydroxide in n-propyl alcohol. The procedure has been extended to the formation of a more complex product, diazo-... 

The addition of 2-diazopropane or 3-diazopentane to (112) results in exo-endo mixtures of both the triazoline (113) and the bicyclo[2.1,0]pentane (114). However, with the 1,2,3,4-tetramethyl analogue of (112) no addition occurs, Surprisingly, the imide (115) incorporates two and three molar equivalents of methylene from diazomethane to give products of spirocyclopropanation at C-4. Monocyclopropana-tion of (116) at the least substituted double bond proceeds efficiently when diazo-acetic ester decomposition is catalysed by copperfn) and similar monoaddition to... 

Polyethylene had been produced by von Peckmann in the 19th century by the decomposition of diazomethane. Polypropylidene (-CH-lCCaHg) isomeric with polypropylene had also been obtained by the decomposition of diazopropane. Later, low melting, amorphous... 

The relationship of the nitrous acid and nitrosoamide methods of deamination is more tenuous in water since only one example of the i nitrosoamide decomposition in aqueous media has been reported. The decomposition of A -nitroso-A -n-propylbenzamide in dimethyl-formamide-water (60/40 by vol) yielded a propyl benzoate fraction containing 9% of the isopropyl isomer and a propanol fraction con- taining 33% of isopropyl alcohoP . The nitrous acid deamination of n-propylamine under the same conditions yielded an alcohol fraction containing 31% of isopropyl alcohoP. The similarity in the isomer contents of the alcohol portions suggests that common intermediates were involved. The less extensive isomerization of the benzoates may be a reflection of the shorter lifetime of the propyl cations trapped by negatively charged coimter ions compared to those trapped by neutral solvent molecules on the other hand, the role of diazopropane must be determined before definitive conclusions are possible. 

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