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I'm tutoring few Class 12 students for their chemistry exams. I'm stuck with few problems. I don't know, if the key is wrong or I am wrong.


enter image description here

Answer According to me:

Product (A) must be the cyclic diene, as given in option (A). Now, I don't know, what happens when you heat cyclic diene with selenium. But I do know that, $SeO_2$ oxidizes allylic position of alkene into alcohol. But, none of the options given are fitting into that argument

Answer given in the book:


How come?

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Some pre-aromatic hydrocarbons can be easily oxidized by sulfur or similar rather weak oxidants into aromatic hydrocarbons. It is different type of reactions and it is not general – permeakra Jan 15 '13 at 8:00
@claws in future try to give appropriate title for the question. Title for this question is vague! – Eka Jan 15 '13 at 13:28
@t3st: I wanted to but I couldn't think of a better title. If you can, kindly suggest – claws Jan 18 '13 at 20:37
up vote 10 down vote accepted

Assuming your Product A is correct then product B should be benzene. Selenium act as a mild oxidizing agent at temperature 220 to 330. In the above reaction selenium oxidizes cyclohexadiene to form benzene.

Below is a reaction in which 1-methyl-1,3-cyclohexadiene is converted into toluene. enter image description here

you can also go to this link for more info

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