Hydroxyl migration

Fig. 17. Doubly labelled ethylene glycol substrates used to investigate the stereospecificity of hydroxyl migration.

The eationie iron migrating toward the cathode, and the anionic hydroxyl migrating toward the anode form soluble ferrous hydroxide ... 

It must be pointed out that transformations of this type do not take place stepwise, as indicated above the ultimate change is equivalent to the simultaneous separation of the hydroxyl group and attachment of the migrating... 

The hydroxyl ions migrate inward, attracted by the positive charge that is produced by the ferrous ion generated near the corroding surface (Fig. 3.4). Other anions such as carbonate, chloride, and sulfate also concentrate beneath the shell. Carbonate may react with ferrous ions to form siderite (FeCOa) as in Reaction 3.4 (Fig. 3.7) ... 

The benzoate ester is one of the more common esters used to protect alcohols. Benzoates are less readily hydrolyzed than acetates, and the tendency for benzoate migration to adjacent hydroxyls, in contrast to acetates, is not nearly as strong. Benzoates can be forced to migrate to a thermodynamically more stable position. ... 

All rearrangements of 20-oximino steroids have thus far given only the product arising from migration of the large steroid residue rather than the smaller C-21 methyl group. This is a consequence of the fact that only the oxime with the hydroxyl furthest removed, and therefore trans, to the bulk of the steroid, is formed. 

Pregnenolone is transported from the mitochondria to the ER, where a hydroxyl oxidation and migration of the double bond yield progesterone. Pregnenolone synthesis in the adrenal cortex is activated by adrenocorticotropic hormone (ACTH), a peptide of 39 amino acid residues secreted by the anterior pituitary gland. 

Silyl groups have found broad appeal as protective groups because their reactivity and stability can be tailored by varying the nature of the substituents on the silicon. Their ability to migrate from one hydroxyl to another is a property that can be used to advantage, but more often, it is a nuisance. The migratory apti-... 

Migration of a BOC is normally not observed, but in the following case a BOC group moved to a hydroxyl. The stabilizing effect of the tosyl group makes this possible. ... 

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