Methylene Derivatives as Intermediates in Polar Reactions. VIII. Difluoromethylene in the Reaction of Chlorodifluoromethane with Sodium Methoxide¹

Abstract

DIFLUOROMETHYLENE IN THE REACTION OF CHLORODIFLUOROMETHANE 5493 temperature was kept under 35' by external cooling. When the reaction became sluggish, more catalyst was added. Reduction was complete when a viscous yellow oil appeared and only a faint odor of nitrobenzene could be detected." Water was added and the mixture placed in an icesalt-bath. The yellow oil soon crystallized. The crude azoxybenzene was removed by rapid filtration. Some of the impurities oiled out leaving behind a yellow solid. The oil was chilled and the process repeated for an additional yield of crude azobenzene. The azoxybenzene was recrystallized from alcohol, yield 5.5 g. (6570), m.p. 34-35:.On a second recrystallization the product melted a t 35-36 .2,2'-Dimethy1azoxybenzene.-To 10 g. of o-nitrotoluene (0.073 mole) was added 9 ml. of lOOYo hydrazine hydrate (0.18 mole) and 20 ml. of 95% ethanol. Some Raney nickel catalyst was introduced. There was much effervescence and the mixture turned slightly green, then yellow. The temperature of the reaction was kept under 35". When the reaction became less vigorous, the solution was orange. More catalyst was added and the mixture allowed to stand a t 0" overnight. The resulting orange-yellow crystals of 2,2'-dimethylazoxybenzene were collected by filtration and recrystallized from a mixture of alcohol and water. A second crop was obtained by adding water to the mother liquor, from the original filtration and treating the resulting dark orange-red oil with dil. HC1 until it crystallized. The total yield was 3.2 g. (39%), m.p. 57.5-58.5".18 4,4'-Dimethy1azoxybenzene.-Ten grams of p-nitrotoluene (0.073 mole) was suspended in a solution of 9 ml. of 1 0 0~o hydrazine hydrate (0.18 mole) and 30 mi. of 9570 ethanol. Some Raney nickel catalyst was introduced and the mixture stirred for several hours. The p-nitrotoluene gradually dissolved and yellow crystals of 4,4'-dimethylazoxybenzene were deposited. When effervescence had ceased, the product was filtered and recrystallized from a mixture of alcohol and water. This yield was 3.4 g. (427,), m.p. 7O-7l0.l8

Difluoromethylation of some C–H acids with chlorodifluoromethane under conditions of phase transfer catalysis (PTC)

“…It means that both active particles, i.e., carbanions and difluorocarbene are generated under PTC conditions. According to Hine et al [32,33] chlorodifluorocarbanion is not involved in alkaline hydrolysis of freon R-22. We found that it hydrolyzed (via difluorocarbene) when passed through a 50% aq.…”

Reactions of aliphatic fluoro-alcohols with CHClF2 at atmospheric pressure

“…In the case of CH 3 OH (or CH 3 ONa), the mechanism for the formation of the orthoformate had been proposed by Hine and Porter [12], and been verified by Lee et al [13]. The Scheme 1.…”

“…The reaction of CH 3 CH 2 CH 2 OH (1e) gave only small amount of 3e (Table 3, Entry 5). It was reported that the difluorocarbene was generated by the reaction of alkoxide and CHClF 2 (Scheme 7) [12]. In the cases of 1c, 1d and 1e, the alkoxide would not be formed efficiently due to the low acidity of alcohols compared with 1a and 1b.…”

“…The difluorocarbene was inserted to the OH bond of the alcohol to afford the difluoromethylated ether (Scheme 2) [12]. Here, it was natural to consider another pathway of the difluoromethylation, which was the protonation of ROCF 2 À generated by the reaction of alkoxide with the difluorocarbene (Scheme 2).…”

Synthesis and antibacterial activity of 6315-S, a new member of the oxacephem antibiotic.

“…The extract was washed with water, dried with sodium sulfate and evaporated to dryness. The residue was chromatographed on silica gel to give 9 (3.7 g, 108 %) as a foam containing small amounts of solvents; IR (CHCl3) cm-1 1788, 1720,1668; NMR (CDCl3) 5 (10) A solution of p-methylbenzyl chloroformate (3.4 g) in methylene chloride (2 ml) was added to a mixture of 9 (3.38 g), pyridine (3.6 ml) and methylene chloride (3 ml) at -20°C.…”