Dichloro ether

CH3OCH2CI, /-PT2NEt, 0°, 1 h 25°, 8 h, 86% yield. This is the most commonly employed procedure for introducing the MOM group. The reagent chloromethylmethyl ether is reported to be carcinogenic, and dichloromethylmethyl ether, a by-product in its preparation, is considered even more toxic. A preparation that does not produce any of the dichloro ether has been reported." ... 

Reaction of Dichloro Ethers ivith Allylbenzo bi thiophenes... 

If carboxylic acid esters are readily available, they provide a convenient basis for the preparation of acid halides. Modified phosphorus halides, like 2,2,2-trichloro-l,3,2-benzodioxaphosphole can be applied successfully. This reagent forms first a 1,1-dichloroalkyl ether, which decomposes to the acid chloride (equation 16). The reaction conditions are rather drastic. For instance -butyl benzoate has to be heated for 4 h at 180 °C in order to get a 90% yield of benzoyl chloride. The only stable and isolable 1,1-dichloro ether is a,a-dichloromethyl methyl ether, which, as described above, is used as a mild reagent for the conversion of carboxylic acids to their chlorides. Similarly severe conditions are required if the chlorine or bromine adduct of triphenylphosphine is selected. This reaction may be catalyzed by BF3. It has been applied successfully to unsaturated esters and to the cleavage of lactones. 

Because the exploitation of the chemistry of unprotected phosphonylated acetaldehydes is handicapped by the sensitivity of the P-C bond in acidic media, a reliable alternative procedure for the preparation of dialkyl 1-chloro-1-formylmethylphosphonates from dialkyl 2-ethoxy-vinylphosphonates has been developed. Room-temperatme chlorination of 2-ethoxyvinylphosphonates with dry chlorine in CCI4 followed by hydrolysis of the phosphonylated a,p-dichloro ethers with water at 50-60°C gives the expected monochlorinated aldehydes in 73-82% yields (Scheme 5.70). A similar treatment with bromine in water at 0°C converts diisopropyl 2-ethoxyvinylphosphonate smoothly into diisopropyl 1-bromo-1-formylmethylphosphonate in 92% yield. ... 

A preparation that does not produce any of the dichloro ether has been reported. ... 

In discontinuous operation the reaction is continued until the vapor issuing from the column reaches a temperature of 64°. Fractionation of the products from 599 g of mono-chloromethyl methyl ether then gives 225 g of the 1,1- and 459 g of the l,l -dichloro ether. Monochloromethyl methyl ether is regenerated by passing the HC1 produced into methanol and formaldehyde.520... 

Under certain conditions tt,/ -dichloro ethers (cf. page 170) react as a mixture of chloroacetaldehyde, alcohol, and HC1, e.g., in the synthesis of 2-amino-thiazole from 1,2-dichloroethyl ethyl ether and thiourea in water. 

The radical chlorination of ethers with iodosoben ne dichloride has been studied further enol ethers react with this reagent to give 1,2-dichloro-ethers, without the secondary products obtained when chlorine itself is used. 

G. B. Bagdasaryan, L. S. Airiyan, and M. G. Indzhikyan. Reaction of dichloro ethers with tetra-n-butyldiborane. Arm. Khim. Zhur., 1977, 30, 661. 

Glycerol ct-dichlorohydrin, sym-dichloroiso-propyl alcohol, 1,3-dichloro-2-hydroxypropane, CH2CI-CHOH-CH2C1. Colourless liquid with an ethereal odour b.p. 174-175" C. Prepared by passing dry HCl into glycerin containing 2% elhanoic acid at 100-1 lO C. Converted to x-epichlorohydrin by K.OH, Used as a solvent for cellulose nitrate and resins. 

The following liquids may be used (boiling points are given in parentheses) — chlorobenzene (132-3°) bromobenzene (155°) p cymene (176°) o-dichloro-benzene (180°) aniline (184°) methyl benzoate (200°) teti-alin (207°) ethyl benzoate (212°) 1 2 4-trichlorobenzene (213°) iaopropyl benzoate (218°) methyl salicylate (223°) n-propyl benzoate (231°) diethyleneglycol (244°) n-butyl benzoate (250°) diphenyl (255°) diphenyl ether (259°) dimethyl phth ate (282°) diethyl phthalate (296°) diphenylamine (302°) benzophenone (305)° benzyl benzoate (316°). 

Dichlorobutane. Place 22-5g. of redistilled 1 4-butanediol and 3 ml. of dry pyridine in a 500 ml. three necked flask fitted with a reflux condenser, mechanical stirrer and thermometer. Immerse the flask in an ice bath. Add 116 g. (71 ml.) of redistilled thionyl chloride dropwise fix>m a dropping funnel (inserted into the top of the condenser) to the vigorously stirred mixture at such a rate that the temperature remains at 5-10°. When the addition is complete, remove the ice bath, keep the mixture overnight, and then reflux for 3 hours. Cool, add ice water cautiously and extract with ether. Wash the ethereal extract successively with 10 per cent sodium bicarbonate solution and water, dry with anhydrous magnesium sulphate and distil. Collect the 1 4-dichloro-butane at 55-5-56-5°/14 mm. the yield is 35 g. The b.p. under atmospheric pressure is 154 155°. 

Silyl ethers serve as preeursors of nucleophiles and liberate a nucleophilic alkoxide by desilylation with a chloride anion generated from CCI4 under the reaction conditions described before[124]. Rapid intramolecular stereoselective reaction of an alcohol with a vinyloxirane has been observed in dichloro-methane when an alkoxide is generated by desilylation of the silyl ether 340 with TBAF. The cis- and tru/u-pyranopyran systems 341 and 342 can be prepared selectively from the trans- and c/.y-epoxides 340, respectively. The reaction is applicable to the preparation of 1,2-diol systems[209]. The method is useful for the enantioselective synthesis of the AB ring fragment of gambier-toxin[210]. Similarly, tributyltin alkoxides as nucleophiles are used for the preparation of allyl alkyl ethers[211]. 

The chloronium ion intermediate can react with water to produce the desired propylene chlorohydrin, with chloride ion to produce 1,2-dichloropropane, or with propylene chlorohydrin to produce isomers of dichloro-dipropyl ether. 

Dichloro-l,l-difluoroethyI Ether CHCl2CF20Ar Formation/Cleavage... 

The example shown in Eq. (6.5) was conducted using 0.5 mole of bis-(2-mer-captoethyl) ether and 0.5 mole of 1,8-dichloro-3,6-dioxaoctane. The base was sodium hydroxide (1 mole) and between 900 and 2,000 mL of ethanol were used. The exact quantity of ethanol used in this synthesis is not clear from the experimental description. The reaction time was somewhere between 7 and 14 hours (again, unspecified), after which time the product (6) was isolated by vacuum distillation, as a viscous oil, in 27% yield. Similar approaches were utilized by this group for the synthesis of other analogs ". ... 

Parham and co-workers have studied the addition of dichloro- and dibro-mocarbene to cyclic enol ethers and the transformations of the resulting dihalocyclopropanes. ... 

Conversion of a carbonyl to a gem-dichloro roup is carried out with phosphorus pentachloride [67, 6S] (equations 51 and 52). Under these conditions, 1,4-dicatbonyl compounds give cyclic ethers [67] (equation 53). 

Miller et al. [9] hypothesized rules on the regioselectivity of addition from the study of the base-catalyzed addition of alcohols to chlorotnfluoroethylene. Attack occurs at the vinylic carbon with most fluorines. Thus, isomers of dichloro-hexafl uorobutene react with methanol and phenol to give the corresponding saturated and vinylic ethers The nucleophiles exclusively attack position 3 of 1,1-dichloro-l,2,3,4,4,4-hexafluoro-2-butene and position I of 4,4-dichloro-l,l,2,3,3,4-hexafluoro-1-butene [10]. In I, l-dichloro-2,3,3,4,4,4-hexafluoro-l-butene, attack on position 2 is favored [J/] (equation 5) Terminal fluoroolefms are almost invariably attacked at tbe difluoromethylene group, as illustrated by the reaction of sodium methoxide with perfluoro-1-heptene in methanol [/2J (equation 6). 

The addition of nucleophiles to cyclic fluoroolefins has been reviewed by Park et al. [2 ]. The reaction with alcohols proceeds by addition-elimination to yield the cyclic vinylic ether, as illustrated by tlie reaction of l,2-dichloro-3,3-di-fluorocyclopropene Further reaction results in cyclopropane ring opening at the bond opposite the difluoromethylene carbon to give preferentially the methyl and ortho esters of (Z)-3-chloro-2-fluoroacrylic acid and a small amount of dimethyl malonate [29] (equation 8). 

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