Synthesis of Alkenes via FGI

E2 with bulky base alkene Is major product 

Introduction to Strategies for Organic Synthesis, First Edition. Laurie S. Starkey. 2012 John Wiley Sons, Inc. Published 2012 by John Wiley Sons, Inc. 

Dehydration (loss of H2O) of an alcohol is promoted by treatment with a strong, non-nucleophilic acid (such as H2SO4 or H3PO4) and heat. Alcohol dehydration involves an El mechanism with a carbocation intermediate. Since carbocations can rearrange, the double bond can end up anywhere on the carbon chain, and the most stable, most highly substituted alkene is expected as the major product (follows Zaitsev s rule, with possible rearrangement of the carbon skeleton). The planar carbocation intermediate also results in a loss of stereochemistry so the more stable stereoisomer will be produced as the major product (trans or E isomer). The dehydration reaction is most useful when only a single product is possible otherwise, a mixture of alkene products is likely to be obtained. 

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