Dichloroethane acidity

In early designs, the reaction heat typically was removed by cooling water. Crude dichloroethane was withdrawn from the reactor as a liquid, acid-washed to remove ferric chloride, then neutralized with dilute caustic, and purified by distillation. The material used for separation of the ferric chloride can be recycled up to a point, but a purge must be done. This creates waste streams contaminated with chlorinated hydrocarbons which must be treated prior to disposal. 

Methyl-5-aminothia2ole-4-carboxylic acid is diazotized with isoamyl nitrite in the presence of furan in 1.2-dichloroethane to give a mixture of products 163 (53%), 164 (33%). 165 (11%), and 166 (3%) (Scheme 104) (334). This reactivity experiment was carried out to examine the possibility of the occurrence of 4,5-dehydrothiazole (hetaryne). Hetaryne intermediates seem not to be involved as an intermediate in the reaction. The formation of 163 through 166 can be rationalized in terms of the intermediacy of 166a. 

Phenyl-4-methyl-A-2-thiazoline-5-one (220) treated with excess SOjClj in dichloroethane and the crude product treated with thioacetic acid yields the 4-thioacetyl derivative (221) (Scheme 111) (446). 

A general one-step method for preparation of primary and secondary nitroparaffins from amines by oxidation with y -chloroperbenzoic acid in 1,2-dichloroethane has been reported (68). This method is particularly useful for laboratory quantities of a wide variety of nitroparaffins because a large number of amines are readily available from ketones by oxime reduction and because the reaction is highly specific for nitroparaffins. 

Both the carboxyl and the mercapto moieties of thioglycolic acid are acidic. Dissociation constants at 25°C are for pR, 3.6 pi, 10.5. ThioglycoHc acid is miscible ia water, ether, chloroform, dichloroethane and esters. It is weakly soluble ia aHphatic hydrocarbons such as heptane, hexane. Solvents such as alcohols and ketones can also react with thioglycolic acid. 

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). 

Dehydrochlorination of 1,1,2-trichloroethane [25323-89-1] produces vinyHdene chloride (1,1-dichloroethylene). Addition of hydrogen chloride to vinyHdene chloride in the presence of a Lewis acid, such as ferric chloride, generates 1,1,1-trichloroethane. Thermal chlorination of 1,2-dichloroethane is one route to commercial production of trichloroethylene and tetrachloroethylene. 

Addition Chlorination. Chlorination of olefins such as ethylene, by the addition of chlorine, is a commercially important process and can be carried out either as a catalytic vapor- or Hquid-phase process (16). The reaction is influenced by light, the walls of the reactor vessel, and inhibitors such as oxygen, and proceeds by a radical-chain mechanism. Ionic addition mechanisms can be maximized and accelerated by the use of a Lewis acid such as ferric chloride, aluminum chloride, antimony pentachloride, or cupric chloride. A typical commercial process for the preparation of 1,2-dichloroethane is the chlorination of ethylene at 40—50°C in the presence of ferric chloride (17). The introduction of 5% air to the chlorine feed prevents unwanted substitution chlorination of the 1,2-dichloroethane to generate by-product l,l,2-trichloroethane. The addition of chlorine to tetrachloroethylene using photochemical conditions has been investigated (18). This chlorination, which is strongly inhibited by oxygen, probably proceeds by a radical-chain mechanism as shown in equations 9—13. 

Dichloroethane is produced commercially from hydrogen chloride and vinyl chloride at 20—55°C ia the presence of an aluminum, ferric, or 2iac chloride catalyst (8,9). Selectivity is nearly stoichiometric to 1,1-dichloroethane. Small amounts of 1,1,3-tfichlorobutane may be produced. Unreacted vinyl chloride and HCl exit the top of the reactor, and can be recycled or sent to vent recovery systems. The reactor product contains the Lewis acid catalyst and must be separated before distillation. Spent catalyst may be removed from the reaction mixture by contacting with a hydrocarbon or paraffin oil, which precipitates the metal chloride catalyst iato the oil (10). Other iaert Hquids such as sdoxanes and perfluorohydrocarbons have also been used (11). 

Hydrolysis. Heating 1,2-dichloroethane with excess water at 60°C in a nitrogen atmosphere produces some hydrogen chloride. The rate of evolution is dependent on the temperature and volume of the aqueous phase. Hydrolysis at 160—175°C and 1.5 MPa (15 atm) in the presence of an acid... 

Oxidation. Atmospheric oxidation of 1,2-dichloroethane at room or reflux temperatures generates some hydrogen chloride and results in solvent discoloration. A 48-h accelerated oxidation test at reflux temperatures gives only 0.006% hydrogen chloride (22). Addition of 0.1—0.2 wt. % of an amine, eg, diisopropylamine, protects the 1,2-dichloroethane against oxidative breakdown. Photooxidation in the presence of chlorine produces monochloroacetic acid and 1,1,2-trichloroethane (23). 

Other Routes. A unique process that produces vinyl chloride, trichloroethylene, dichloroethane, and trichloroethane simultaneously has been developed by Produits Chemiques Pechiney-Saint-Gobain in France (31). Dichloroethylene is chlorinated directly at low temperature to tetrachloroethane, which is then thermally cracked to give trichloroethylene and hydrochloric acid. The dichloroethylene feed is coproduced with vinyl chloride in a hot chlorination reactor, using chlorine and ethylene as feedstocks. 

The vapor is thea withdrawa from the stiH as distillate. The changing Hquid composition is most coavenieafly described by foUowiag the trajectory (or residue curve) of the overall composition of all the coexistiag Hquid phases. An exteasive amouat of valuable experimental data for the water—acetoae—chloroform mixture, including biaary and ternary LLE, VLE, and VLLE data, and both simple distillation and batch distillation residue curves are available (93,101). Experimentally determined simple distillation residue curves have also been reported for the heterogeneous system water—formic acid—1,2-dichloroethane (102). 

Acetic acid-water Pinched system Ethyl acetate, propyl acetate, diethyl ether, dichloroethane, butyl acetate ... 

Di-(/)-chlorophenyl)-acetic acid has been made by the action of alcoholic potassium hydroxide on l,l-di-(/>-chlorophenyl)-2,2-dichloroethane by the action of barium hydroxide on DDT in ethylene glycol and by the condensation of chlorobenzene with glyoxylic acid. ... 

The chemistry of Lewis acid-base adducts (electron-pair donor-acceptor complexes) has stimulated the development of measures of the Lewis basicity of solvents. Jensen and Persson have reviewed these. Gutmann defined the donor number (DN) as the negative of the enthalpy change (in kcal moL ) for the interaction of an electron-pair donor with SbCls in a dilute solution in dichloroethane. DN has been widely used to correlate complexing data, but side reactions can lead to inaccurate DN values for some solvents. Maria and Gal measured the enthalpy change of this reaction... 

The mixture is cooled, the organic phase washed with water and dried over sodium sulfate. The toluene Is evaporated and the residue taken up in 2 liters of normal acetic acid, with cooling. It is allowed to crystallize in the cold, filtered to remove the insoluble portion and the base precipitated from the filtrate by the addition of sodium carbonate this is extracted with dichloroethane and the organic phase dried over sodium sulfate. After evaporation of the solvent an oil is distilled, BP 225° to 230°C/0.1 mm, weight 340 grams, yield 58%. The hydrochloride prepared by the action of gaseous hydrogen chloride on this oil in ethyl ether melts at 140°C. 

Another common reaction is the chlorination of alkenes to give 1,2-dihaloalka-nes. Patell et al. reported that the addition of chlorine to ethene in acidic chloroalu-minate(III) ionic liquids gave 1,2-dichloroethane [68]. Under these conditions, the imidazole ring of imidazolium ionic liquid is chlorinated. Initially, the chlorination occurs at the 4- and 5-positions of the imidazole ring, and is followed by much slower chlorination at the 2-position. This does not affect the outcome of the alkene chlorination reaction and it was found that the chlorinated imidazolium ionic liquids are excellent catalysts for the reaction (Scheme 5.1-39). 

The stage is now set for the crucial polycyclization event. Tertiary carbinol 8, derived from the action of methyllithium on enone 9, is a rather unstable substance, and it was submitted to the polycyclization reaction without purification. When intermediate 8 is treated with trifluoroacetic acid (TFA) and the vinyl cation trapping agent ethylene carbonate in 1,2-dichloroethane at 0°C, the desired... 

The preparation of silver phthalocyanine (PcAg) is carried out by metal insertion into metal-free phthalocyanine from silver(I) nitrate. The reaction is performed in dimethylformamide291 or in a mixture of 1,2-dichloroethane, sodium acetate and acetic acid.231... 

ArH Hexane Chloroform Dichloroethane Nitrobenzene 99% aq. acetic acid... 

Only the propionic acid-contaminated HBr gave catalyst deactivation under the conditions tested. Figures 7 and 8 show the results of the dibromoethane, dichloroethane, phenol, and fluorobenzene tests. 

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