Triphenylmethyl chloride reaction with hydroxyl groups

The most widely recognized method of selective etherification of sugars and polysaccharides involves the reaction of primary alcohol groups with triphenylmethyl (trityl) chloride. Helferich60 has described the selective character of this reagent, whose rate of reaction with primary hydroxyl groups is many fold that with secondary groups. 

The rates of reaction of triphenylmethyl chloride with several characteristic compounds are given ( 7) in Table I, which also illustrates the effect of the trityl chloride concentration. For the 8-fold excess, the primary alcoholic group of the galactose derivative reacts 226 times as rapidly as the secondary alcoholic group of the glucose derivative. However, the difference between the primary alcoholic group of the sorbose derivative and the secondary hydroxyl of the glucose derivative is only 34 times. 

The triphenylmethyl (trityl) group is removed under even milder conditions, and is an important hydroxyl-protecting group, especially in carbohydrate chemistry. This group is introduced by reaction of the alcohol with triphenylmethyl chloride via an SnI substitution. Hot aqueous acetic acid suffices to remove the trityl group. The ease of removal can be increased by addition of electron-releasing substituents. The p-methoxy derivatives have been employed for this purpose. ... 

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