how to know which any alcohol isomer, on dehydration, gives the greatest number of different alkenes?

Question

aaronq · Answer

the one attached to the largest number of different things. Most often a tertiary alcohol (within the limitations of antiperiplanar hydrogen availability) can give you the largest number of different products - given that the groups attached to the alcohol bearing the carbon are different of course. This is also a factor that lowers the yield in synthesis when you want solely one product.

somy · Answer

one of the tricks that i use is i just look at the chain, if OH is attached to a carbon that is not in the middle of the chain and is to the right or left of the middle carbon (wherever it is but not at the edges) will give you greatest number of different alkenes :D 
is it a good trick to use tho? @aaronq