Benzal chloride catalyst

Continuous chlorination of benzene at 30—50°C in the presence of a Lewis acid typically yields 85% monochlorobenzene. Temperatures in the range of 150—190°C favor production of the dichlorobenzene products. The para isomer is produced in a ratio of 2—3 to 1 of the ortho isomer. Other methods of aromatic ring chlorination include use of a mixture of hydrogen chloride and air in the presence of a copper—salt catalyst, or sulfuryl chloride in the presence of aluminum chloride at ambient temperatures. Free-radical chlorination of toluene successively yields benzyl chloride, benzal chloride, and benzotrichloride. Related chlorination agents include sulfuryl chloride, tert-huty hypochlorite, and /V-ch1orosuccinimide which yield benzyl chloride under the influence of light, heat, or radical initiators. 

Benzal chloride is hydrolyzed to benzaldehyde under both acid and alkaline conditions. Typical conditions include reaction with steam in the presence of ferric chloride or a zinc phosphate catalyst (22) and reaction at 100°C with water containing an organic amine (23). Cinnamic acid in low yield is formed by heating benzal chloride and potassium acetate with an amine as catalyst (24). 

Aromatic Ring Reactions. In the presence of an iodine catalyst chlorination of benzyl chloride yields a mixture consisting mostly of the ortho and para compounds. With strong Lewis acid catalysts such as ferric chloride, chlorination is accompanied by self-condensation. Nitration of benzyl chloride with nitric acid in acetic anhydride gives an isomeric mixture containing about 33% ortho, 15% meta, and 52% para isomers (27) with benzal chloride, a mixture containing 23% ortho, 34% meta, and 43% para nitrobenzal chlorides is obtained. 

No catalyst) Benzyl chloride Benzal chloride Benzotrichloride Rapid side-chain chlorination of toluene proceeds in the dark with sulphuryl chloride in the presence of dibenzoyl peroxide (O 001-0 005 mol per mol of SOjClj) as catalyst ... 

Significant synthetic applications of the nickel-salen catalysts are the formation of cycloalkanes by reduction of <>, -a-dihaloalkanes255,256 and unsaturated halides,257,258 the conversion of benzal chloride (C6H5CHC12) into a variety of dimeric products 259 the synthesis of 1,4-butanediol from 2-bromo- and 2-iodoethanol260 or the reduction of acylhalides to aldehydes261 and carboxylic acids.262... 

The electrochemistry of cobalt-salen complexes in the presence of alkyl halides has been studied thoroughly.252,263-266 The reaction mechanism is similar to that for the nickel complexes, with the intermediate formation of an alkylcobalt(III) complex. Co -salen reacts with 1,8-diiodo-octane to afford an alkyl-bridged bis[Co" (salen)] complex.267 Electrosynthetic applications of the cobalt-salen catalyst are homo- and heterocoupling reactions with mixtures of alkylchlorides and bromides,268 conversion of benzal chloride to stilbene with the intermediate formation of l,2-dichloro-l,2-diphenylethane,269 reductive coupling of bromoalkanes with an activated alkenes,270 or carboxylation of benzylic and allylic chlorides by C02.271,272 Efficient electroreduc-tive dimerization of benzyl bromide to bibenzyl is catalyzed by the dicobalt complex (15).273 The proposed mechanism involves an intermediate bis[alkylcobalt(III)] complex. 

Electrogenerated nickel(I) salen has been employed catalytically for the reduction of benzal chloride [152] and for the reductive coupling of 2-bromo- and 2-iodoethanol to prepare 1,4-butanediol [153]. Electrogenerated nickel(I) cyclams have been used as catalysts for the reductive intramolecular cyclizations of o-haloaryl... 

Cobalt(I) salen has been employed as a catalyst for the reduction of the following species benzal chloride [159] benzotrichloride [160] 1-bromobutane, 1-iodobutane, and 1,2-dibromobutane [161] iodoethane [162], benzyl chloride [163], and ethyl chloroacetate [164]. Rusling and coworkers have investigated the use of cobalt(I) salen, as well as vitamin Bi2s and cobalt(I) phthalocyanine, in both homogeneous phase and bicontin-uous microemulsions for the catalytic reduction of vicinal dibromides [165] and... 

Benzaldehyde is prepared by hydrolysis of benzal chloride, for example in acidic media in the presence of a catalyst such as ferric chloride, or in alkaline media with aqueous sodium carbonate. Part of the commercially available benzaldehyde originates from a technical process for phenol. In this process, benzaldehyde is a byproduct in the oxidation, with air, of toluene to benzoic acid. 

Electrochemical reduction of nickel(I)(salen) in the presence of benzal chloride at a carbon electrode in DMF leads to a variety of monomeric and dimeric products171. Cyclic voltammetric studies using benzylic halides showed that carbanions can bring about auto-catalytic processes by acting as electron-transfer catalysts (Scheme 16)172. 

Among hydroxybenzaldehydes, the o- and p- hydroxy isomers are the most important for commercial applications in agricultural, flavor and fragance, pharmaceutical or polymer fields (ref. 1). The two main processes for the manufacture of hydroxybenzaldehydes are both based on phenol. The most widely used process is the saligenin process. Hydroxybenzyl alcohols (o- and p- isomers) are produced from base - catalyzed reaction of formaldehyde with phenol (ref. 2). Air oxidation of these alcohols over a suitable catalyst (based on palladium or preferentially on platinum) produces hydroxybenzaldehydes (ref. 3). The Reimer -Tiemann process allows the coproduction of o- and p- hydroxybenzaldehydes (ref. 4). Treatment of phenol with aqueous chloroform and sodium hydroxide leads to benzal chlorides which are rapidly hydrolyzed by alkaline medium to aldehydes. The previous processes need two chemical steps and produce salt effluents. 

Benzaldehyde is a liquid with an agreeable odor, which boils at 179°, and has the specific gravity 1.0504 at 15°. It can be formed by oxidizing benzyl alcohol, or distilling calcium benzoate with calcium formate. It is manufactured by heating benzal chloride with milk of lime, or by oxidizing benzyl chloride with a solution of lead nitrate. It has been prepared from toluene directly by electrolytic oxidation or by oxidation with air in the presence of a catalyst. 

The gas-phase reaction of benzotrichloride with hydrogen fluoride over a chromium trifluoride catalyst is claimed to give a 93% yield of benzotri-fluoride, and pentafluorobenzaldehyde reacts with sulphur tetrafluoride to give a-jtf-heptafluorotoluene, C,Fj-CFjH (see also Vol. 1, p. 208), a better route to which apparently involves the fluorination of 2,3,4,5,6-pentafiuoro-benzal chloride. Bromination of the heptafluoro-compound gives perfluoro-... 

Depending on the reaction conditions, the action of elemental chlorine can lead either to addition or substitution on the aromatic ring or to substitution in the aliphatic side-chain. The side-chain chlorinated all l aromatics are exceptional important intermediates for the production of numerous chemicals, including dyes, plastics, pharmaceuticals, flavors, perfumes, pesticides, catalysts, inhibitors, etc. The toluene derivatives benzyl chloride, benzal chloride and benzotrichloride have the greatest commercial significance. 

Sulfur tetrafluoride [7783-60-0] SF, replaces halogen in haloalkanes, haloalkenes, and aryl chlorides, but is only effective (even at elevated temperatures) in the presence of a Lewis acid catalyst. The reagent is most often used in the replacement of carbonyl oxygen with fluorine (15,16). Aldehydes and ketones react readily, particularly if no alpha-hydrogen atoms are present (eg, benzal fluoride [455-31-2] from benzaldehyde), but acids, esters, acid chlorides, and anhydrides are very sluggish. However, these reactions can be catalyzed by Lewis acids (HP, BF, etc). 

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