Ina note under this title, Gerrard and Nechvatal1 have reported the conversion of neopentyl alcohol, (CH3)3C.CH2.OH (here written ROH), by thionyl and phosphorus halides into the esters RO.SOCl and RO.PCl2, inter alia. They remark that Whitmore and Rothrock2 demonstrated the resistance of neopentyl alcohol to the replacement of its hydroxyl group by halogen, through the agency of thionyl chloride and phosphorus tribromide. They add that we3 have attributed this to the steric hindrance of what they call “end-on approach” to the α-carbon atom. They state that Whitmore and Rothrock leave the impression that neopentyl alcohol does not react at all with the halides specified; but that the work of Gerrard enabled Gerrard and Nechvatal to predict the probability of an easy “broadside approach” of the reagents. We should like to add some points to this statement of the relation between the different investigations.