Chlorination Chloromethylation

PoJy (3,3-bis (chloromethyl) oxelane), chlorinated polyether (R CHiCl) is widely used for injection moulding and coaling. 

Further chlorination of the chloromethyl ketone gives the corresponding trichloromethyl ketone which then undergoes hydrolysis to form chloroform... 

Alkylation. Ben2otrifluoride can also be alkylated, eg, chloromethyl methyl ether—chlorosulfonic acid forms 3-(trifluoromethyl)ben2yl chloride [705-29-3] (303,304), which can also be made from / -xylene by a chlorination—fluorination sequence (305). Exchange cyanation of this product in the presence of phase-transfer catalysts gives 3-(trifluoromethylphenyl)acetonitrile [2338-76-3] (304,305), a key intermediate to the herbicides flurtamone... 

PMB Sulfon ation Acylation Chloromethylation Ring chlorination... 

An 80% yield of benzyl chloride is obtained with sulfuryl chloride as chlorinating agent. Yields of >70% of benzyl chloride are obtained by the zinc chloride-catalyzed chloromethylation of benzene but formation of bis-chloromethyl ether presents a health hazard for this reaction pathway. 

Dichlorobenzyl chloride (l,2-dichloro-4-chloromethylbenzene) containing some 2,3-dichlorobenzyl chloride is produced by the chloromethylation of o-dichlorobenzene ia oleum solution (73). Chlorination of 2-chloro-6-nitrotoluene at 160—185°C gives a mixture of 2,6-disubstituted benzal chloride and 2,6-dichlorobenzyl chloride (74). 

Side-Chain Chlorinated Xylene Derivatives Only a few of the nine side-chaia chlotinated derivatives of each of the xylenes are available from direct chlorination. All three of the monochlotinated compounds, a-chloro-o-xylene (l-(chloromethyl)-2-meth5lbenzene [552-45-4] a-chloro-y -xylene (1-(ch1oromethy1)-3-methylhenzene [620-19-9] a-chloro-/)-xylene (1-(ch1oromethy1)-4-methylhenzene [104-82-5]) are obtained ia high yield from partial chlorination of the xyleaes. 1,3-Bis(ch1oromethy1)henzene [626-16-4] can be isolated ia moderate yield from chlorination mixtures (78,79). 

Chloromethane Chlorine atom Chloromethyl radical Hydrogen chloride... 

Chloromethyl radical Chlorine Dichloromethane Chlorine atom... 

In the reactions of 2,5-disubstituted thiophenes elimination of an a-substituent occurs to a much greater extent than in the benzene series. The Friedel-Crafts acetylation of 5-bromo-2-ethylthiophene in the presence of SnCE gives 2-ethyl-5-acetyIthiophene. Elimination of an a-bromine occurs also in the chloromethylation of 2,5-di-bromothiophene, leading to a mixture of 2-bromo-5-chloromethyIthio-phene and 2,5-dibromo-3-chloromethyIthiophene. Bromine atoms at both the and -position are exchanged for chlorine in the... 

In addition, it was clear that the presented scheme does not exhaust all the possible paths of anomalous chlorination. Thus, 4-acetyl-l,3,5-trimethylpyrazole with 4-5 moles of phosphorus pentachloride gave mainly 4-Q ,/3-dichlorovinyl-5-chloromethyl-l,3-dimethylpyrazole, and its precursor (according to GLC data) was the dichloride. It could be possible that in the case of 4-chlorovinyl derivatives of pyrazole the chlorination at the p position is facilitated by the electron-donating characteristics of the 4-pyrazolyl radical (86TH1). 

The chloromethyl free radical then attacks another chlorine molecule and produces dichloromethane along with a Cl atom ... 

Several chlorophyll derivatives have been prepared by electrophilic substitution, inter alia by formylation reactions. Adopting methods from corrin chemistry.50 alkylation with chloro-methyl methyl ether (caution toxic),32k chloromethyl methyl sulfide,51 and dichloromethyl methyl ether (caution toxic)52 in the presence of Lewis acids are the methods of choice to introduce carbon residues into the chlorin frame work. The compounds listed below have been prepared by these methods. 

Rigo e.t al,6j were the first to propose that head addition does occur but is immediately followed by a 1,2-chlorine atom shift. The viability of 1,2-chlorine atom shifts is well established in model studies and theoretical calculations.64 Experimental support for this occurring during VC polymerization has been provided by NMR studies on reduced PVC /lfl Starnes et a/.61 proposed that head addition is followed by one or two 1,2-chlorine atom shifts to give chloromethyl or dichloroethyl branch structures respectively (Scheme 4.8). There also is kinetic data to support this hypothesis. 

The checkers used beads of chloromethylated polymer available from Bio. Rad. Laboratories, Richmond, California (Bio Beads S-X2). Chlorine analysis (Note 3) showed that the resin contained 1.06 milli-equivalents of chlorine per gram, as specified by the manufacturer. 

The first kinetic study used chloromethyl methyl ether as chlorinating reagent and acetic acid as solvent, viz. reaction (188)381... 

As has been mentioned in an earlier section, aqueous chlorination of sulphoxides leads to sulphones. If excess reagents are used, sulphonyl chlorides may be formed directly from sulphoxides in good yields (equation 75)89,90,193. In order for this reaction to be synthetically useful, the sulphoxide used should be symmetrical. The product is presumably formed in a stepwise manner via the sulphinyl chloride [RS(0)C1] and the sulphinic acid [RS(0)0H]. In the case of chloromethyl dichloromethyl sulphoxide, the only sulphonyl chloride formed is chloromethanesulphonyl chloride (equation 76) and this may be readily separated from the other products by distillation90,193. Similarly, oxidation of dichloromethyl methyl sulphoxide and methyl trichloromethyl sulphoxide with chlorine in aqueous acetic acid leads to the formation of methanesulphonyl chloride in 75% and 86% yields respectively. Other species are also produced but these are much more volatile and thus easily removed (equations 77 and 78). In the absence of acetic acid the yields are somewhat reduced. 

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