CH2OH substituent on Chair Conformations and Haworth Project

[ngu9997]

How do you know if the CH2OH will point equatorial up or axial down (up or down I guess) in the chair or haworth? They seem to always point up; when will I have a situation where it points down and how would I know in the name or elsewhere if the CH2OH should be pointing down?

 

[Ygggdrasil]

I'm not sure I completely understand your question. In general, it is more energetically favorable for larger groups like CH2OH to be equatorial because large axial groups will run into each other and clash sterically.