Chloromethylation capacity

The capacity of the product is about 0.5 meq/g. Sulfomethylcellulose has been prepared by using monochloromethanesulfonate, made from dichloromethane and sodium sulfite. Phosphonomethylcellulose, a bifunctional cation exchanger, is prepared by reacting disodium chloromethyl-phosphonate and cellulose ... 

The styrene-furfural condensation product on chloromethylation followed by amination with dimethylamine affords a weak-base resin having a capacity of 1.4—1.5 meq/g. The relative affinities of this resin for anions follow the sequence, COj > NOj" > SO > HCOJ > OAc for the Cl form of the resin. The operational efficiency of this resin increases with lowering the pH of the solution to be treated. 

Anchoring polymers are prepared from chloromethylated styrene-divinylbenzene copolymers of either 1 equiv Cl/g or 4 equiv Cl/g capacity. These resins arc stirred for 24 h in refluxing CHC13, with either 1,4-diazabicyclo[2.2.2]octane, hexamethylenetetramine, or TMEDA. The polymers are filtered off, washed with ClIClj, acetone and Et20, then dried overnight under vacuum at 25 °C. Nitrogen elemental analysis and chloride ion titration gives a value of 80-90% quaternarization. 

In connection with the introduction of a chromatographic system for the analysis of inorganic anions, in which the separator column was coupled directly to the conductivity cell, Fritz et al. [16,17] developed a series of macroporous, macroreticular anion exchangers of low capacity, featuring highly crosslinked PS/DVB particles as substrate (XAD-1, Rohm Haas, Philadelphia, PA, USA). The substrate was chloromethylated... 

In 1979, Gjerde and Fritz [4] published a study in which anion-exchangers with exchange capacities ranging from 0.04 to 1.46 mequiv/g were prepared from macro-porous polystyrene-DVB resins. The capacities were controlled by varying the time of chloromethylation and then alkylating the chloromethyl groups. 

Anion-exchange resins of variable but low exchange capacities are produced under mild conditions and short reaction times in the chloromethylation reaction. Conditions for the amination are chosen to convert as much of the chloromethyl group as possible to the quaternary ammonium chloride, although experience indicates that some of the chloromethyl remains imreacted. 

To ascertain the effect of functional group structure on selectivity, the various resins should have a very similar exchange capacity so that identical elution conditions could be used for each resin. To accomplish this, the relative reactivities of various amines with chloromethylated XAD-1 had to be determined. Then the degree of chloro-methylation of XAD-1 could be adjusted so that the aminated resins would have similar capacities. 

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