Chloroformic acid esters sulfonic

In the literature a number of different techniques for the preparation of a-sulfo fatty acid esters can be found. There is equipment for small-scale and commercial scale sulfonation. Stirton et al. added liquid sulfur trioxide dropwise to the fatty acids dispersed or dissolved in chloroform, carbon tetrachloride, or tetrachoroethylene [44]. The molar ratio of S03/fatty acid was 1.5-1.7 and the reaction temperature was increased to 65 °C in the Final stage of sulfonation. The yield was 75-85% of the dark colored a-sulfonated acid. The esterification of the acid was carried out with either the a-sulfonic acid alone, in which case the free sulfonic acid served as its own catalyst, or with the monosodium salt and a mineral catalyst. 

Solid esters are easily crystallisable materials. It is important to note that esters of alcohols must be recrystallised either from non-hydroxylic solvents (e.g. toluene) or from the alcohol from which the ester is derived. Thus methyl esters should be crystallised from methanol or methanol/toluene, but not from ethanol, n-butanol or other alcohols, in order to avoid alcohol exchange and contamination of the ester with a second ester. Useful solvents for crystallisation are the corresponding alcohols or aqueous alcohols, toluene, toluene/petroleum ether, and chloroform (ethanol-free)/toluene. Esters of carboxylic acids derived from phenols are more difficult to hydrolyse and exchange, hence any alcoholic solvent can be used freely. Sulfonic acid esters of phenols are even more resistant to hydrolysis they can safely be crystallised not only from the above solvents but also from acetic acid, aqueous acetic acid or boiling n-butanol. Note that sulfonic esters of lower alcohols, e.g. methanol, are good alkylating agents. 

A mixture of 9,9-dimethyl-2, 5-dihydroxy-6,7-benzomorphan hydrochloride, calcium carbonate and toluene-4-sulfonic acid but-3-ynyl ester in dimethylformamide is heated and subsequently concentrated under reduced pressure. The residue is taken up in a mixture of water and chloroform (1 1) and the aequeous phase extracted twice with chloroform/butanol (9 1). The combined organic phases are concentrated under reduced pressure to give the... 

Carboxylic, and arylsulfonic acid halides react rapidly with pyridines generating 1-acyl- and 1-arylsulfonylpyridinium salts in solution, and in suitable cases some of these can even be isolated as crystalline solids. The solutions, generally in excess pyridine, are commonly used for the preparation of esters and sulfonates from alcohols and of amides and sulfonamides from amines. 4-Dimethylaminopyridine (DMAP) is widely used (in catalytic quantities) to activate anhydrides in a similar manner. The salt derived from DMAP and t-butyl chloroformate is stable even in aqueous solution at room temperature. " ... 

Insertions into Aldehyde C-H Bonds. The a-diazo ketones (and esters) derived from diazomethane and an acid chloride (or chloroformate) will also insert into the C-H bond of aldehydes to give 1,3-dicarbonyl derivatives. The reaction is catalyzed by SnCL, but some simple Lewis acids, such as BF3 etherate, also work. The reaction works well for ahphatic aldehydes, but gives variable results with aromatic aldehydes, at times giving none of the desired diketone (eq 32). StericaUy hindered aldehydes will also participate in this reaction, as illustratedin eq 33 with the reaction of ethyl a-diazoacetate and pivaldehyde. In a related reaction, a-diazo phosphonates and sulfonates will react with aldehydes in the presence of SnCL to give the corresponding -keto phosphonates and sulfonates. This reaction is a practical alternative to the Arbuzov reaction for the synthesis of these species. 

Pentene reacts with chlorosulfonic acid (one equivalent) in chloroform solution at 0-5 °C to give a mixture of the 2- and 3-sulfonic acids (80 and 20% respectively), indicating that preferential attack occurs at the most nucleophilic carbon atom. Chlorosulfonic acid in a non-polar solvent may also react with alkenes, e.g. propene 8, by addition to give the chlorosulfonate ester 9 such esters, however, react further with alkenes so the overall reaction is as shown (Scheme 1). 

Another mild method for the activation of the oxime hydroxyl group consists in its conversion into an ester moiety or, more commonly, into a sulfonate derivative. They can be rearranged into amides under basic [371] or acidic [372] conditions also involving Lewis acids [366]. Trimethylsilyl chloride [373] and chloroformate [374] in the presence of a Lewis acid can also be used. Amidines have been obtained by Beckmann rearrangement of a tosyloxime in the presence of benzotriazol [375]. 

A moderate stream of chlorine passed at —20° into a soln. of N,N -dibenzoylcystine diethyl ester in chloroform for 40 min. followed immediately by a stream of ethylene until the odor has changed, the ethereal suspension of the crude product treated at —10° with an ethereal soln. of monoperphthalic acid, allowed to warm to room temp., and the product isolated after 2 days j5-carbethoxy-/ -benzoylamino-j -chlorodiethyl sulfone. 

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