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Consider thiol anion (RS^T) and alkoxy anion (RO^T). Which of the following statements is correct ? a. RS^T is less basic but more nucleophilic than RO^T b. RS^T is more basic and more nucleophilic than RO^T c. RS^T is more basic but less nucleophilic than RO^T d. RS^T is less basic and less nucleophilc than RO^T

Consider thiol anion (RS^T) and alkoxy anion (RO^T).
Which of the following statements is correct ?
a. RS^T is less basic but more nucleophilic than RO^T
b. RS^T is more basic and more nucleophilic than RO^T
c. RS^T is more basic but less nucleophilic than RO^T
d. RS^T is less basic and less nucleophilc than RO^T

Grade:12th pass

2 Answers

Kevin Nash
askIITians Faculty 332 Points
9 years ago

(a) On moving down a group, the basicity & nucleophilicity are inversely related, i.e. nucleophilicity increases while basicity decreases. i.e RS^T is more nucleophilic but less basic than RO^T. This opposite behavior is because of the fact that basicity and nucleophilicity depends upon different factors. Basicity is directly related to the strength of the H-element bond, while nuclepphilicity is indirectly related to the electronegativity of the atom to which proton is attached.

Dinesh Chopra
13 Points
6 years ago
RSH is a stronger acid than ROH since, the conjugate base is more stable ( megs charge on sulphur is more stable due to larger size). Since acid is  strong the conjugate base is weak. Also RS- being more stable is more nucleophilic in nature.

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