An unsaturated hydrocarbon (A) absorbs two molecules of hydrogen to give a saturated hydrocarbon and absorbs two molecules of bromine to give a tetrabromoderivative. Compound (A) absorbstwo molecules of ozone to give a diozonide. The diozonideon warming with Zn/H2Ogives a mixture of three compounds- acetaldehyde, acetone and propan-1,3-dial. What is A?

Dear Student,

Please find below the solution to the asked query:

1) Since the unsaturated hydrocarbon (A) absorbs two molecules of hydrogen to give a saturated hydrocarbon, there is either a possibility of an triple bond or two double bonds in the compound.

2) The absorption of two molecules of bromine which give a tetrabromo derivative also justifies the same assertion as said above.

3) Compound (A) on absorption of two molecules of ozone gives a diozonide, hence the unsaturation is present at two different locations.
 
4) Diozonide on reaction with Zn/HCl dissociates at its O-O axis giving either an aldehyde or a keto product, hence from the products thus obtained, the compound (A) can be traced back as shown in the Figure.




Hence, the compound (A) is 2-methyl-hept-2,5-diene.



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