Chloromethyl chloroformate, hydrolysis

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

During the next fifty years the interest in derivatives of divalent carbon was mainly confined to methylene (CHg) and substituted methylenes obtained by decomposition of the corresponding diazo compounds this phase has been fully reviewed by Huisgen. The first convincing evidence for the formation of dichlorocarbene from chloroform was presented by Hine in 1950. Kinetic studies of the basic hydrolysis of chloroform in aqueous dioxane led to the suggestion that the rate-determining step was loss of chloride ion from the tri-chloromethyl anion which is formed in a rapid pre-equilibrium with hydroxide ions ... 

Alkyl chloroformates, R0C(=0)C1, might be expected to hydrolyse rapidly by an SNl-type process, reminiscent of the hydrolysis of alkoxy ethers such as chloromethyl ether. Similarly, carbamates would be expected to react by a similar mechanism because of the possible stabilisation of the acylium ion formed, viz. 

Chloromethylation.1 Chloromethyl methyl ether has been generally used for electrophilic aromatic chloromethylation, but it is highly toxic and now considered a carcinogen. Chloromethylation can be effected by use of a trimethylsilyl ether (1) of a chlorohydrin prepared as shown from trioxane and chlorotrimethylsilane in the presence of stannic chloride in chloroform. This reagent, generated in situ, is effective for chloromethylation of styrene in the presence of SnCl4 any excess is easily decomposed by hydrolysis. Bromomethylation is possible by replacement of ClSi(CH3)3 by BrSi(CH3)3. 

However, as the formaldehyde formed by the hydrolysis of monochloromethyl chloroformate is also oxidised by potassium permanganate it must be first determined by titration with iodine solution. Then, by subtracting from the number of ml. permanganate solution decolorised, twice the number of ml. of iodine solution used (for formaldehyde needs twice as much oxygen as formic acid for its oxidation), the result is the number of ml. permanganate corresponding to the quantity of formic acid present and from this the chloromethyl formate in the sample may be calculated. 

Amino-5-chloromethyl-3-cyanopyrazine 1-oxide with triphenylphosphine in dimethylformamide at 80-90° gave 2-amino-3-cyano-5-(triphenylphosphonio)-methylpyrazine 1-oxide chloride (97) (520) and the 5-bromomethyl analogue reacted similarly with triphenylphosphine in propan-2-ol (542). Compound (97) on hydrolysis with 30% aqueous ethanol containing a small amount of triethylamine gave 2-amino-3-cyano-5-methylpyrazine 1-oxide and thus enabled removal of the chloro substituent from the chloromethylpyrazine (529) compound (97) with triethylamine and acetaldehyde (and other aldehydes) in chloroform at room temperature gave 2-amino-3-cyano-5-(prop-l -enyl)pyrazine 1-oxide (and other alkenyl analogues) (529). 

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