Diazomethane formation

It appears to be a stable covalent highly crystalline compound (unlike other metal methanediazoates). Alkanediazoates are easily converted to diazoalkanes, so should be regarded as capable of detonation. (Though named by the author as a methanedia-zoate, it is indexed and registered in CA as a nitrosomethylamide salt) [1], A sample of the freshly synthesised compound was dissolved in dichlorodideuteromethane and sealed into an NMR tube. Four days later, when the tube was being opened for recovery of the sample, the tube exploded. This was attributed to diazomethane formation, possibly from reaction with traces of moisture sealed into the tube [2], See other heavy metal derivatives, n-o compounds... 

Reaction of diaryl ditellurides with diazomethane-formation of diaryl telluroketals (typical procedure). Di-p-methoxyphenyl ditelluride (2.34 g, 5 mmol) in ether (30 mL) is treated dropwise, at 0°C and while stirring, with an ethereal solution of diazomethane until disappearance of the red colour of the ditelluride. Evolution of N2 ensues. The product is obtained by evaporation of the solvent. RecrystaUization from hexane or EtOH gives colourless crystals (2.41 g (100%) m.p. 98-99°C). 

The photolysis of diazirine °° at 3130 A yields ethylene and nitrogen methylene is probably formed in the primary process. The long wavelength absorption ( max = 3200 A) had been identified as the allowed (a, n ) transition and semi-empirical Huckel calculations indicate that the methylene produced must be (Ai) or (Bi). There is evidence that methylene produced from the photolysis of diazirine is more selective than methylene from diazomethane, owing to decreased excess translational energy. At low pressures 5-30 torr, diazomethane was identified as an intermediate by its absorption spectrum and the question arises, is methylene formed directly, or does it arise from decomposition of diazomethane The quantum yield of disappearance of diazirine is 2.0+0.5 and the quantum yield of diazomethane formation is about 0.2. The intermediate diazomethane is... 

With cyclohexene, the yields of fused cyclopropanes depend dramatically on the method of generation of the carbene, and on the substituents of the diazo derivatives. For a comparison, (diethoxyphosphoryl)(phenyl)diazomethane reacted with cyclohexene to give the cyclopropane adduct 3c in 54% yield in the presence of copper powder, and in 22% yield under photolytic conditions. With (dimethoxyphosphoryl)(methyl)diazomethane, formation of the cyclopropane derivative was not observed. ... 

Diazirine was used as the carbene precursor in an experiment to make diazomethane from methylene and nitrogen in the gas phase. As shown by means of labeled nitrogen, there was 4% diazomethane formation. During the past 10 years thermal as well as photochemical decomposition of 3-chloro- and 3-bromodiazirine has been investigated in detail. Compounds 175 and 176 as well as analogous compounds are easily obtained by reaction of amidines with hypohalites according to Graham. ... 

Diazirine was used as the carbene precursor in an experiment to make diazomethane from methylene and nitrogen in the gas phase. As shown by means of labeled nitrogen, there was 4% diazomethane formation.185... 

The energy difference between diazirine and diazomethane, interesting from the point of view of their isomerism, came from MS measurements (63JCP(39)3534). The appearance potentials of the CH2 ion, common to both compounds, yielded a difference in heats of formation of 125kJmor A strong peak in the mass spectrum of 3-chloro-3-methyl-diazirine (50) with relative mass 55 was ascribed to the methyldiazirinium ion (51). 

Formation of diazomethane from diazirine was also observed in a solid nitrogen matrix on irradiation (64JCP(41)3504). Labeling experiments demonstrated that elimination and uptake of nitrogen occurred. 

However, in the case of a-substituted unsaturated esters (4), as for example methacrylic or tiglic acid esters, diazomethane addition results in the formation of stable A pyrazolines (5). The latter products require halogen acids for conversion to the isomeric nonconjugated A -pyrazolines (6). 

The addition of diazomethane to a,/l-unsaturated ketones, e.g., benzalace-tone and benzalacetophenone, results in A -pyrazolines (16) which decompose thermally to the conjugated ketones (17). Cyclopropane formation is not observed in this instance. 

With -3-ketones, i.e., (11), diazomethane addition proceeds with attack at the A -bond leading to stereospecific formation of [2a,la-c]-A -pyrazolines (12). 

Although A" -3-keto steroids are inert to diazomethane, Fieser ° observed pyrazoline formation (24) with the more reactive cholest-4-ene-3,6-dione (23). 

Identification of the product(s) resulting from the reaction of heterocyclic compounds with diazomethane has been used in attempts to elucidate their tautomeric composition (for summaries, see references 7 and 41). This work was based on the assumption that if a compound which is capable of existing in both an —NH and an —OH form produced only the =NMe derivative when it w as treated with diazomethane, it existed entirely in the =NH form. On the other hand, formation of the —OMe derivative was interpreted to mean that a finite amount of the compound existed in the —OH form. In some cases the tautomer present in the solid state w as concluded to be different from that present in solution for example, 41 42 gave a higher proportion of the 3,4-dimethoxy derivative when ethereal diaz-... 

Dipolar additions of diazomethane to acetylenes under mild conditions are restricted to monosubstituted acetylenes thus the formation of pyrazole derivatives 1 (1,3-dipolar addition, C=C isomerization, then methylation) confirms the existence of a terminal acetylene in caryoynencins (87TL3981) (Scheme 5). 

While Kakisawa et al. (87TL3981) reported formation of Wmethylpyrazole 1, Yamaguchi et al. obtained the NH derivative 2 by reaction of caryoynencins with diazomethane in ethyl acetate at 0°C (94BSJ1717 95JMC5015). The 1,3-dipolar addition was quite sensitive to the solvent employed, and a very low yield of pyrazole derivative 2 was obtained in ether or methanol (Scheme 5). 

For the preparation of the parent substance, cyclic diazomethane (67), formaldehyde, chloramine, and ammonia were reacted. Diaziri-dine formation was successful in about 20% yield the diaziridine condensed with further formaldehyde to high molecular weight products the diaziridine detected by its oxidizing power was nonvolatile. Oxidation with dichromate in dilute sulfuric acid led to gaseous diazirine (67) [Eq. (56)]. It was only investigated in solution. 

Preliminary investigations on the formation of carbenes from diazirines have already been made available. Frey and Stevens recently reported the photolysis of cyclic diazomethane. Cyclic diazomethane was irradiated in the gaseous phase with light of wavelength... 

The foregoing investigations which demonstrate the equilibrium character of the primary step in methylation with diazomethane necessitate the additional assumption for Eq. (9) that the complex 1 shows the properties of an oriented ion pair (there is evidence " which can be thus interpreted) and the formation of 1 is reversible. It should be noted that in no stage of the process (including complex 1) is a mesomeric anion formed. A direct methylation is only possible when the compound retains a fixed structure throughout the reaction. 

Divergent reports are available regarding the action of diazomethane on triacetic acid lactone (83). In the first investigations the sole formation of 6-methyl-2-methoxypyran-4-one (85) or of 6-methyl-4-methoxypyran-2-one (84) " w as reported. Later it was shown that a mixture of both compounds is formed albeit the 2-methoxy derivative (85) in small yield. The discrepancies are in... 

The reactions of diazomethane with heterocycles containing a ketonic grouping in the ring do not differ, in principle, from those of alicyclic ketones (see footnotes 3 and 177) ring expansion and the formation of epoxides compete. In general, ring expansion is the more important reaction for example, tetrahydropyran-4-one (99) is converted to l-oxacycloheptan-4-one (100) (60%) and 4,4 -epoxy-4-methyltetrahydropyran (101) (23%). ... 

If the carbonyl grou]) in the 3-position of N-methylisatin or tlii-ana])hthencquinone is blocked by formation of an oxime (cf. 112), A -methylation of the oxime group occurs instead of ring expansion on reaction with diazomethane. In methanol, thianaphthenequinone oxime iV-mcthyl ether (113) then undergoes ring opening catalyzed by diazoniethane (113 114). 

---