Dioxane, decomposition chloroformates

Pentacarbonyl(methoxymethylcarbene)chroniiuin(0) is a dull-yellow, crystalline solid mp 34°. It slowly decomposes in the solid state at room temperature in air, but may be stored at 5° for a few days before appreciable decomposition is observed. It is soluble in aliphatic hydrocarbons such as n-pentane, n-hexane, n-heptane, and other common laboratory solvents such as benzene, 1,4-dioxane, tetrahydrofuran, chloroform, dichloromethane, and methanol, and is slightly soluble in ethanol. The infrared spectrum (cyclohexane solution) has v(CO) bands at 2065, 1985, 1965, and 1950 cm-1. The H nmr spectrum in chloroform-d shows the methoxy proton resonance at t6.15 and the methyl proton resonance at t7.70. Other physical properties are reported in the literature.6,7... 

During the next fifty years the interest in derivatives of divalent carbon was mainly confined to methylene (CHg) and substituted methylenes obtained by decomposition of the corresponding diazo compounds this phase has been fully reviewed by Huisgen. The first convincing evidence for the formation of dichlorocarbene from chloroform was presented by Hine in 1950. Kinetic studies of the basic hydrolysis of chloroform in aqueous dioxane led to the suggestion that the rate-determining step was loss of chloride ion from the tri-chloromethyl anion which is formed in a rapid pre-equilibrium with hydroxide ions ... 

B. Bicyclo[1.1.1]pentane-1,3-dicarboxytic acid (3). A 1-L, three-necked, round-bottomed flask, equipped with a mechanical stirrer, addition funnel, and thermometer is charged with a solution of 43.3 g (108 mol) of sodium hydroxide in 315 mL of water and 25.5 mL (79.1 g, 0.495 mol) of bromine. The mixture is cooled to 0°C. A solution of the diketone (10 g, 0.066 mol) obtained in Part A in 36 mL of dioxane is added dropwise at such a rate that the temperature does not exceed 3°C (Note 7). After the addition is finished, the reaction mixture is stirred for 1 hr at 0°C, then overnight at room temperature. Sodium bisulfite (1.8 g) is added and the solution is extracted with chloroform (3 x 50 mL). Subsequently, 36 mL of coned hydrochloric acid is added to the aqueous layer. After the acidified solution is cooled to room temperature, the mixture is continuously extracted with diethyl ether for 50 hr (Note 8) in an extraction apparatus. Evaporation of ether from the extract yields 9.68 g (94.5% from diketone 2) of pure diacid 3, mp 302-305°C, with decomposition [lit.4 mp, 305°C (d)] (Note 9). 

A white to creamy-white crystalline powder. M.p. about 240°, with decomposition. A solution in dioxan is dextrorotatory. Practically insoluble in water soluble 1 in 75 of ethanol, 1 in 15 of warm ethanol, and 1 in 1100 of chloroform very slightly soluble in ether sparingly soluble in acetone and methanol. 

The reaction behaviour for the thermal decomposition of the chlorosulphites in solution parallels that of the chloroformates very closely. Thus, Boozer and Lewis " found that when 2-pentyl chlorosulphite is thermally decomposed in dioxane solution at 62 °C both 2-chloropentane and 2-pentene are formed. The relative amounts of the substitution and elimination reactions in this instance are 51 % and 49 % respectively. With allylic chlorosulphites, substitution is accompanied by rearrangement . Boozer and Lewis - have carried out configurational checks on the mechanism of thermal decomposition in solution and deuterium isotope studies have also been made . As with the chloroformates, the experimental evidence points to transition states of a polar nature . Gas phase decompositions of chlorosulphites have been studied by Rieche and Nau-mann and Geiseler et a/. - and radical-chain mechanisms have been proposed . 

Chloroformates are sufficiently reactive to undergo decomposition in solution. A four-centered S yl mechanism was originally suggested however, subsequent kinetic studies favor an initial decomposition to ions. The first-order decomposition of substituted a-phenethyl chloroformates was studied in dioxane and toluene by carbon dioxide evolution , viz. 

Properties White to practically white crystalline powder odorless. Mp 235C with some decomposition. Very slightly soluble in water soluble in alcohol, chloroform, acetone, methanol, dioxane. 

In the course of study of the reaction of NO with aromatic amines, the effect of solvents on the reaction mechanism has been established. NO reacts in ethereal solvents (tetrahydrofuran (THF), dioxane, ethoxy ethane (EtOEt), dimethylether (DME)) or chloroform to give deamination products [33]. This solvent effect was explained by the competitive decomposition of diazonium ions via accepting an electron from NO to give the phenyl radical, and hydrogen (H)-atom abstraction from the solvent leads to the deamination product ... 

The thermal polymerization of diphenyldiacetylene in vacuo was claimed to yield a polymer possessing structure [12] with a molecular weight of approximately 1100 10). It was soluble in solvents such as benzene, chloroform, ether, dioxane, and dimethylformamide and had excellent thermal stability. Its weight loss at 350°C was below 5% and no marked decomposition was observed even at 500°C. The material did not form peroxides with oxygen, and exhibited photoconductivity in the region of its optical absorption. 

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