Sat January 26, 2013 By: Prashaant Malaviya

What is Saytzeff rule? How it is applied? What is Azo Dye test?

Expert Reply
Sun January 27, 2013
Saytzeff rule: The formation Alkenes by the dehydration of alcohols (using concentrated H2SO4) the hydrogen atom will be removed (to remove as water) from the adjacent carbon atom linked to the less number of hydrogen atoms.

Example: In the dehydration of Butane – 2-ol, 2-butene is formed.

CH3-CH=CH-CH3+H2O ------------>    CH3-CH=CH-CH3
                          concentrated H2SO4
Azo Dye test:
In weakly alkaline medium, phenol reacts with benzenediazonium chloride to form colored substances which are called as azo dyes. The reaction takes place at 273-278 K temperature and also known as coupling reaction.
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