Methylene chloride pyrolysis

Chlorinated by-products of ethylene oxychlorination typically include 1,1,2-trichloroethane chloral [75-87-6] (trichloroacetaldehyde) trichloroethylene [7901-6]-, 1,1-dichloroethane cis- and /n j -l,2-dichloroethylenes [156-59-2 and 156-60-5]-, 1,1-dichloroethylene [75-35-4] (vinyhdene chloride) 2-chloroethanol [107-07-3]-, ethyl chloride vinyl chloride mono-, di-, tri-, and tetrachloromethanes (methyl chloride [74-87-3], methylene chloride [75-09-2], chloroform, and carbon tetrachloride [56-23-5])-, and higher boiling compounds. The production of these compounds should be minimized to lower raw material costs, lessen the task of EDC purification, prevent fouling in the pyrolysis reactor, and minimize by-product handling and disposal. Of particular concern is chloral, because it polymerizes in the presence of strong acids. Chloral must be removed to prevent the formation of soflds which can foul and clog operating lines and controls (78). 

The slow combustion of methylene chloride is a degenerately branched chain reaction it proceeds by a mechanism similar to that involved in the pyrolysis of the same compound which takes place at a slightly higher temperature [153]. The primary chains are the same and several of the chlorinated hydrocarbon minor products are identical. Oxygen is only involved in the conversion of the intermediate dichloroethylene to the final products hydrogen chloride and carbon monoxide. 

The main conclusions of the Round Robin were Karl-Fischer titration is recommended for analysing water in pyrolysis oils. Solids content as ethanol insolubles is accurate for white wood oils but a more powerful solvent, like a mixture of methanol and methylene chloride (1 1) is needed for extractive-rich oils. For the elemental analysis at least triplicates are recommended. Kinematic viscosity is an accurate method for pyrolysis oils. Stability index needs more clarification and testing,- Results of chemical characterisation were not very consistent. It may be necessary to prepare standard solutions with known aniounts of conqiounds for... 

Gas-phase pyrolysis of diazoacetic esters affords y-butyrolactones 220 in moderate yields (79IZV1652). Using Rh(II) catalysts ensures greater yields of lactones and allows the reactions to be carried out in methylene chloride... 

Nitrosyl fluoride, FNO. Of several methods for the preparation of this highly reactive gas reviewed by Andreades, that preferred by du Pont workers is pyrolysis of a mixture of nitrosyl fluoroborate and sodium fluoride. BoswelP of du Pont found that, when a stream of gas generated in this way was passed into a solution of cholesteryl acetate in methylene chloride at 0°, the solution turned deep blue and workup afforded the 5a-fiuoro-6-nitrimine (2) in high yield. This was hydrolyzed by neutral... 

High temperature (800°C), pressure-free hydrothermal treatment of carbosil prepared by pyrolysis of methylene chloride was studied in the paper [38]. The results of hydro-thermal treatment of such adsorbents under the conditions without pressure (800°C) and high pressure of water vapour (250-500°C) are presented in another paper [59]. 

Surface properties of unmodified carbon-silica adsorbents (carbosils X, H, B, Y) and the same adsorbents modified with the products of pyrolysis of n-heptanol (H) and benzyl alcohol (B) in an autoclave (A) and dynamic reactor (R). The carbosils were prepared by the pyrolysis of methylene chloride adsorbents X and Y), n-heptyl alcohol (H) and benzyl alcohol (B) on the silica surface... 

However, this was considered to be suspicious, and the laboratory asked for swabs from three of the victims to be forwarded for comparison, as some sexual activity had been known to have taken place. Methylene chloride extracts of the swabs were taken and evaporated onto the pyrolysis wires, and the experiments were repeated. The results were compared with those of the body lotion taken from the door. 

Two types of CS with very low and large carbon contents were synthesized by pyrolysis of methylene chloride at a surface of nanosilica (Sbet 300 mVg) at the surface concentration of carbon of 0.5 and 40 wt% for CS-1 and CS-2, respectively (Turov et al. 1997a). In order to elucidate the specificity of interactions of adsorbate molecules with silica and carbon deposits, the adsorption of water and benzene was studied (Figure 4.14). In the case of benzene, the spectra for both CS consist of two up-field shift signals, and for more intense signal for CS-1 A8h=-2.7 ppm, while for CS-2 A5h=-2.3 ppm. The second signal has similar values for both samples (A8h=-8 ppm). Clearly, the... 

Seledets, O., Skubiszewska-Zieba, J., Leboda, R., and Gun ko, V.M. 2003. On the surface properties of carbon-silica adsorbents (carboaerosils) prepared by pyrolysis of methylene chloride on the surface of fumed silica (aerosil). Mater. Chetn. Phys. 82 199-205. 

The copolymer material (100 mg) is weighed in a 10 ml volumetric flask and dissolved in 10 ml methylene chloride. Two microlitres of this solution are placed at the centre of a quartz sample tube and allowed to dry. The sample tube is placed inside the platinum coil of the pyrolysis probe which is then inserted into the heated interface. Before initiating the run, 10 min are allowed for any entrapped air, residual solvents or monomers to escape. 

Figures 1.14 and 1.15 show the gas chromatograms of pyrolysis products trapped in 0.01 N H2SO4 solution, for acrylic acid containing latex A and methacrylic acid containing latex B, respectively. In the latex A case (Figures 1.14, 1.15), the 0.01 N H2SO4 solution-trapped products revealed a significant reduction in complexity of peaks and the acrylic acid and methacrylic acid peaks are better resolved from other pyrolysis products. This is a direct result of the low solubility of the nonpolar pyrolysis products in the polar solution. In contrast, the methanol and methylene chloride-trapped products exhibit gas chromatograms of about the same complexity as direct Py-GC pyrograms. This indicates that the selection of 0.01 N H2-SO4 solution as the trapping solvent can properly separate the acrylic acid or methacrylic acid from an abundance of other components...

Methylbenzofuran-3-carbaldehydes undergo ready condensation with Meldrum s acid (isopropylidene malonate) to afford arylmethylene derivatives 83. These on flash vacuum pyrolysis at 500-600 C give 3-dibenzofuranols 84 (Scheme 21). The arylmethylene derivative, e.g., 85, presumably undergoes conversion to a methylene ketene (86, Scheme 22) on pyrolysis, which undergoes a [1,5-H] shift and subsequent cyclization and tautomerization, yielding the dibenzofuranol 87. The derived methyl ether 88 has been converted by mild acetylation with acetyl chloride and aluminum chloride and subsequent boron trichloride-induced demethylation to the natural product ruscodibenzofuran (8). A limitation is imposed on this method because 3-acetyl-2-methyldibenzofurans fail to condense with Meldrum s acid so that l-methyl-3-dibenzofuranols are not available by this method. ... 

The trienone (74), either by reaction with diazomethane and pyrolysis of the derived pyrazoline or by treatment with dimethylsulphoxonium methylide anion, yielded28 the 1 a,2 -methylene derivative (75). Epoxidation followed by the action of hydrogen chloride gave (77). The methylene bridge was re-formed by the reaction of collidine, the product being (76). Halogenated steroids of use in determining the metabolic fate of 16-chloro-oestrone methyl ethers and of chlormadinone acetate have been synthesized.29... 

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