Benzal chloride preparation

The aromatic aldehydes are formed by reactions analogous to those made use of in the preparation of aliphatic aldehydes. The method which is best adapted to the preparation of the aromatic compounds is not the same as that used most conveniently in the aliphatic series. Acetic aldehyde and its homologues are usually prepared by oxidizing primary alcohols. Benzoic aldehyde, a typical aromatic aldehyde, is manufactured by heating benzal chloride, prepared from toluene, with water in the presence of lime —... 

The 2- and 4-monochloro and 2,4- and 3,4-dichlorobenzyl chloride, benzal chloride, and benzotrichlorides are manufactured by side-chain chlorination of the appropriate chlorotoluene. -Chlorobenzotrichloride (1 -chioro-4-trichioromethylhenzene) can be prepared by peroxide-catalyzed chlorination of -toluenesulfonyl chloride or di-/)-toluylsulfone (71). 2,4-Dichlorobenzotrichloride (1,3-dich1 oro-4-trichi oromethylhen zene) is obtained by the chlorination of 2-chloro-4-chlorosulfonyltoluene (72). 

This acid, of the formula CgHgCH CHCOOH, occurs in a number of, essential oils in the free state. It is prepared artificially by heating benzal chloride with sodium acetate. It has a sweet odour. It is a crystalline substance, melting at 133° and boiling at 300°. 

The first synthesis of a cyclopropenone was reported in 1959 by Breslowls who achieved the preparation of diphenyl cyclopropenone (11) by reacting phenyl ketene dimethylacetal with benzal chloride/K-tert.-butoxide. The phenyl chloro carbene primarily generated adds to the electron-rich ketene acetal double bond to form the chlorocyclopropanone ketal 9, which undergoes 0-elimination of HC1 to diphenyl cyclopropenone ketal 10. Final hydrolysis yields 11 as a well-defined compound which is stable up to the melting point (120—121 °C). 

The procedure described is essentially that of Ballard and Dehn.1 Stilbene has also been prepared by reduction of desoxy-benzoin,20 benzaldehyde,23 and benzil 2o-2c by dehydrogenation of ethyl benzene,30 toluene,30- 33- 3, and bibenzyl 33-3alkaline reduction of phenylnitromethane,40 phenylnitroacetonitrile,40 and desoxybenzoin 43 by distillation of benzyl sulfone,50 benzyl sulfide,60-63 calcium cinnamate,5 cinnamic acid,5d phenyl cinna-mate,6e-6/ and diphenyl fumarate ie by dehydrohalogenation of a,a -dichlorobibenzyl60 and benzyl chloride 63 by dehalogenation of a,a,c/,a -tetrachlorobibenzyl70 and benzal chloride 73 by the coupling of cinnamic acid and phenyldiazonium chloride 8 by de-... 

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... 

The methine bridge in acridines can be derived from dihalomethanes. Originally sodium carbonate was used, with dichloro- or diiodo-methane, to prepare dibenzacridine (624) from 2-naphthylamine (02JCS280). Subsequently, better yields were obtained when dichloromethane, 1,1-dichloroethane or benzal chloride, 1-naphthylamine, and a solvent were heated, the products being dibenz(c,/z jacridines (624) (06JCS1387). 

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. 

Side-Chain Chlorination of Toluene. Benzyl chloride, used mainly in the manufacture of plasticizers, may be prepared by the thermal or photochemical chlorination of toluene.191,192 In the thermal process chlorine is passed through toluene at 65-100°C. To minimize the formation of benzal chloride and benzotrichloride, the conversion is limited to about 50%. Since the density of the reaction mixture increases linearly with the formation of benzyl chloride,145 measurement of density is used to monitor the progress of the reaction. The overall yield based on toluene is about 90%, and the maximum conversion to benzyl chloride is above 70%. Higher yields in photochemical chlorination may be achieved. 

Ethyl benzalmalonate has been prepared by the esterification of benzalmalonic acid in the presence of concentrated sulfuric acid 4 by the action of benzal chloride on sodiomalonic ester 6 by the condensation of benzaldehyde and malonic ester in the pres-... 

Triphenylmethane has hitherto usually been prepared by the interaction of benzene and chloroform in the presence of aluminium chloride 5 or ferric chloride,2 but the yields are considerably lower. Other methods consist in the action of benzal chloride upon benzene and aluminium chloride,6 in heating benzal chloride and mercury diphenyl,7 and in heating a mixture of benzaldehyde, benzene, and zinc chloride.8... 

Applied to the synthesis of hydrocarbons the following results have been obtained by this new method. 9 10-Diphenyl-9 10-dihydroanthracene is formed by the condensation of benzene and chloroform, whilst in the ordinary Friedel-Crafts reaction (A., 194, 254 227, 107) triphenyl-methane (Preparation 6) is the main product, traces of chlorarylmethanes and tetraphenylethane (B., 26, 1952) being also formed. The same compound is also obtained from benzal chloride and benzene. Carbon tetrachloride and benzene give 9 9 10 10-tetraphenyl-9 10-dihydroanthracene as do also phenylchloroform and benzene. In the older reaction triphenylchloromethane (p. 432) is the chief product. 

The same compound can be prepared from 8 gms. (2 mols.) of benzal chloride, 13 gms. (excess) of benzene, and the above quantities of aluminium and mercuric chloride. The reaction is completed at 50°—55°. Otherwise the details are as already described. 

Reaction XXXIII. (e) Condensation of the Dichlorides of Aromatic Aldehydes with the Sodium Salts of certain Acids. (B., 15, 969.)—This is a modification of the previous reaction used commercially to prepare cinnamic acid, by heating scdium acetate with benzal chloride. The latter is much cheaper than benzaldehyde. 

The process is used on a commercial scale to prepare benzaldehyde by heating benzal chloride with an aqueous suspension of chalk or milk of lime under pressure. Water is sufficient to bring about hydrolysis, the alkali is added to remove the hydrogen chloride formed, and so prevent the reverse reaction taking place. In place of an alkali, a trace of iron powder can be used the reaction here takes a slightly different course, only 1 mol. of water being required for 1 mol. of the dichloride. 

Method I.—20 gms. (1 mol.) of benzal chloride (see p. 350) are refluxed for 4 hours in an atmosphere of carbon dioxide with 200 c.cs. of water and 40 gms. of precipitated chalk in a round flask heated on an oil bath which is kept at 130°. The whole is then steam distilled in an atmosphere of carbon dioxide (see p. 24). The distillate is extracted with ether, the ether removed on a water bath and the residual benzaldehyde purified by means of its bisulphite compound, as described in Preparation 156. 

Method II.—150 gms. (1 mol.) of benzal chloride (see p. 350) are heated in a round-bottomed flask to 30° with agitation 0 5 gms. of iron powder and 25 gms. (excess) of water are then added, and the mixture cautiously heated until hydrogen chloride is evolved (about 100°). Heating may be discontinued until the action subsides, when more heat is applied. About 20 gms. sodium carbonate are added to give an alkaline reaction, and the benzaldehyde distilled in steam in an atmosphere of carbon dioxide and purified as described in Preparation 156. 

Cyclopentadienes can be prepared by double Michael addition of zirconacyclopentadienes with propynoates <1997CC2069> or nucleophilic attack of zirconacyclopentadienes on acyl halides mediated by copper(l) chloride and accompanied by elimination <1995CC1503, 1996TL7521>. Tetraethylzirconacyclopentadiene with benzal chloride in THF in the presence of copper(l) chloride and DMPU yield l,2,3,4-tetraethyl-5-phenylcyclopenta-l,3-diene <2000TL7471>. A series of other similar compounds were prepared from tetra- -propylzirconacyclopenta-diene and 0 ,Q -dichlorotoluene, tetra- -butylzirconacyclopentadiene and 0 ,Q -dichlorotoluene or 0 ,Q -dibromotoluene, as well as some other combinations. Tetraethylzirconacyclopentadiene reacts with l,l-dibromo-l-alkene-3-ynes under the same conditions (copper(l) chloride and DMPU) to yield alkynylfulvenes. 

Benzal chloride, used for the preparation of benzaldehyde, should be free from benzyl chloride. It should be fractionated carefully, therefore, removing the portion boiling below 180°. 

Benzaldehyde is prepared by the hydrolysis of (dichloromethyl)benzene (benzal chloride) in either aqueous acid or aqueous alkali and by the oxidation of toluene with chromium trioxide in acetic anhydride (Scheme 6.3). In the latter synthesis, as the benzaldehyde is formed, it is converted into its diacetate by the acetic anhydride, so preventing further oxidation subsequent hydrolysis generates the aldehyde group. The benzaldehyde has thus been protected from oxidation. Benzyl alcohol can... 

Using this scheme with other diarylacetylenes, or with p-methoxybenzyl chloride instead of benzal chloride, the p-anisyldiphenyl- di-p-anisylphenyl- and tri-p-anisylcyclopropenyl ions could be prepared. Monophenylacetylene is also a suitable component for the reaction and diphenylcyclopropenyl bromide (7) has been synthesized... 

The first cyclopropenone, diphenylcyclopropenone (28), was reported in 1959. This, the most common of the cyclopropenones, was prepared by the reaction of phenylketene dimethylacetal with benzal chloride and potassium r-butoxide. The chlorocyclopro-penone ketal (29) which is produced from these reagents via phenyl (chloro)carbene addition to the ketal undergoes )8-elimination yielding 30 which can be hydrolyzed, in situ, to give the cyclopropenone (equation 25). A series of arylphenylcyclopropenones were prepared using this method. ... 

The preparation of arylcyclopropanes from arylhalomethanes and aryidihalomethanes is usually accompanied by formation of various byproducts. Stilbene formation is generally observed and compounds resulting from C-H insertion are often formed. In some cases a formal byproduct may become predominant and even be formed in good yield. This is the case when benzal chloride is treated with methyllithium. Thus, treatment of a mixture of 2,3-dimethylbut-... 

The appropriate alkene (1 mol) and benzal chloride (10.6 g, 0.066 mol) were placed in a flame-dried, 250-mL three-neck flask, equipped with a dry-ice condenser, low-temperature thermometer, addition funnel and magnetic stirrer. All operations were carried out under a small positive N2 pressure. MeLi (0.10 mol) in EtjO was added over a period of 2.5 h at — 40"C. After completion of the addition, the mixture was stirred for an additional and then poured onto ice. The product was washed with H O and dried (Na2S04), and the excess alkene was allowed to evaporate. The EtjO and remaining alkene were removed under reduced pressure, and the residue was distilled from bulb-to-bulb under vacuum. The analysis of the product was carried out by GC. Cyclopropanes prepared in this manner are compiled in the above table. 

Benzaldehyde is prepared by the hydrolysis of (dichloromethyl)benzene (benzal chloride) in either aqueous acid or aqueous alkali and by the oxidation of toluene with chromium trioxide in acetic anhydride (Scheme... 

Chlorination of toluene under radical conditions (either through the use of an initiator or by photolysis) gives a mixture of mono-, di- and trichlorotoluene. In practice in the perfumery industry, the reaction is run with an excess of toluene present, which means that benzyl chloride is the major product. A little benzal chloride is produced and can be separated and hydrolysed to give benzaldehyde. The major use of benzyl chloride is in the production of benzyl alcohol and its esters. The alcohol is produced by hydrolysis of the chloride. The esters can be prepared by esterification of the alcohol, but it is better economically to prepare... 

Benedict s reagent, 998-999, 1009 Benzal chloride, 415 Benzaldehyde, 407 diethyl acetal of, 669 preparation of, 659 reactions of... 

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