Organic Chemistry Basics - Result Question 69

####21. The IUPAC name of the compound

$CH _2=CH-CH\left(CH _3\right) _2$ is

(1987, 1M)

(a) 1,1-dimethyl-2-butene

(b) 3-methyl-1-butene

(c) 2-vinyl propane

(d) None of these

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Answer:

Correct Answer: 21. (d)

Solution:

  1. A mono-substituted benzoic acid is stronger than a mono-substituted phenol as former being a carboxylic acid. Among the given substituted benzoic acid, ortho-hydroxy acid is strongest acid although $-OH$ causes electron donation by resonance effect which tends to decrease acid strength.

It is due to a very high stabilisation of conjugate base by intramolecular $H$-bond which outweigh the electron donating resonance effect of $-OH$.

The overall order of acid-strength of given four acids is ortho-hydroxybenzoic acid $\left(p K _a=2.98\right)>$ Toluic acid $\left.p K _a=4.37\right)>p$-hydroxybenzoic acid $\left(p K _a=4.58\right)>$ $p$-nitrophenol $\left(p K _a=7.15\right)$



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