[Doom91]

what conditions would favour the intramolecular dehydration of diols and what condition would favour the intermolecular dehydration of the diols if the catalyst is the same sulphuric acid catalyst

[azmanam]

what products would the intramolecular dehydration of a diol give?

[Doom91]

cyclic ether

[azmanam]

potential ring size and overall concentration will be 2 big determining factors

[Doom91]

you mean no of carbons in the ring and the amount of ring strain within the ring ,by the way how does the conc affect the type of minor and major product being formed

[azmanam]

yes.  number of carbons and ring strain will favor intramolecular dehydration - which ring sizes do you think will be favored?

how do you think con'c will effect inter vs intra?  imagine you had a diol as a neat (read: solventless) liquid, and a diol that was 0.0000001 molar in an inert solvent.  Add catalytic acid to both.  which will give intermolecular product preferentially and which will give intramolecular product preferentially?

[Doom91]

 5 or 6 membered ring would be most favourable , smaller deviations from the 109.5degrees for sp3 carbons

[azmanam]

yes.  (and, actually, 3 membered rings close very fast, as well).

[sanderol]

consider entropy!! Entropy would prefer intramolecular.

[Doom91]

I thought 3 membered ring has quite a great amount of ring strain , great deviation from 109.5(abt 49.5), Therefore unstable . why does it form

[azmanam]

because its fast.  The orbitals essentially overlap already.  epoxides can be quite stable and isolated.