50. An alcohol X on heating with concentrated H2SO4
gives an alkene Y which can show geometrical
isomerism. The alcohol X is
(a) CH,CH,CH(OH)CH,
(b) (CH3)2C(OH)CH(CH3)2
(c) (CH3),C(OH)
(d) (CH3),C(OH)CH,CH,
Answers
Geometrical isomerism is shown by an alkene molecule only when two groups attached to each of the carbon atoms of the double bond are different
I know you already have this much idea from before
Also you may be knowing on heating with concentrated H2SO4 an alcohol molecule undergo dehydration to form corresponding alkene molecule
Now,
In option (a)
CH3-CH2-CH(OH)-CH3
on heating dehydration will take place to form following alkene
CH3-CH=CH-CH3
Both carbon atoms of double bond contain two different groups that is
-CH3 and -H
So, it will show geometrical isomerism
Cis and trans but-2-ene are the products
One more product will form -
CH3-CH2-CH=CH2
As terminal carbon of double bond have same groups attached that is two H atoms so this molecule will not show geometrical isomerism
One more thing three products in option (a) will form with -
trans but-2-ene as major products
cis but-2-ene as less major products
And but-1-ene as minor products
According to the stability of alkenes which is proofed by ZAITSEV or SAYTZEFF rules
For the answers of other options
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Answered by an IIT JEE ASPIRANT and all India mathematics OLYMPIAD TOPPER in class 10th