Diazo-diphenylmethane

Similar pressure effects have been observed in the 1,3-dipolar cycloaddition of diazo-diphenylmethane to various alkenes. This is in agreement with a concerted mechanism involving an isopolar activated complex [752, 753] cf. Section 5.3.3. For the 1,3-dipolar cycloaddition of diazo-diphenylmethane to dimethyl acetylenedicarboxylate at 25 °C in n-hexane (AF = —24 cm mol ) and in acetonitrile (AF = —15 cm mol ), the solvent-induced difference AAF is only 9 cm mol this corresponds to a very small rate constant solvent effect, k2(CH3CN)/A 2(n-C6Hi4) = 3.4 [752]. 

Related to Diels-Alder [2 + 2]cycloadditions are 1,3-dipolar cycloadditions, which are known to be far less solvent-dependent cf. Eq. (5-44) in Section 5.3.3. Nagai et al [169] found that the 1,3-dipolar cycloaddition reaction of diazo-diphenylmethane to tetracyanoethene (TONE) is an exception it is 180 times faster in nonbasic trichloro-methane than in the EPD solvent 1,2-dimethoxyethane cf. Eq. (7-25). The second-order... 

The rate of reaction between benzoic acid and diazo-diphenylmethane in 44 non-HBD solvents correlates significantly with all four Koppel-Palm parameters of Eq. (7-50), according to Eq. (7-52) with = 44, r = 0.976, and standard deviation s = 0.188 [15, 116] cf also [117]. 

The KAT equations (7-53) and (7-54) have been widely and successfully applied in the correlation analysis of all kinds of solvent-dependent processes a review on their use in chromatography has been given by Carr [357]. Only two representative examples will be mentioned. Multiple regression of Ig k2 for the reaction between benzoic acid and diazo-diphenylmethane using the KAT equation (7-53), for the same set of 44 non-HBD solvents as used in the Koppel-Pahn treatment of this reaction given in Eq. (7-52), leads to Eq. (7-55a), with n = 44, r = 0.980, and s = 0.171 [15, 268]. 

Zur Reduktion von Diazo-Verbindungen zu Hydrazinen durch Natriumamalgam s.ds. Handb. Bd. X/4, S. 889. So erhalt man z.B. aus Diazoessigsaure Hydrazino-essigsaure, wahrend Diphenyl-diazomethan zu Diphenylmethyl-amin reduziert wird (mit Palladium als Katalysator erhalt man Diphenylmethan). 

In most cases in which dimerization is not dominant, proton transfer to the diazo anion radical is the reaction responsible for the majority of final products. These pathways were studied in detail with diphenyldiazomethane in aprotic solvents without added protic compounds (Bethell and Parker, 1981, 1982 Van Galen et al., 1984). Benzophenone hydrazone and diphenylmethane were the major products in this case (9-31). ... 

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