mo olygl aoi by lphenyiphosphine, and it is the correct answer. which nucleophil
ID: 635568 • Letter: M
Question
mo olygl aoi by lphenyiphosphine, and it is the correct answer. which nucleophilic reagent, Z, will give the most 1,4-addition product with methyl vinyl ketone? A-11 , CH3-C-CH-CH2 (A) LiAIH (B) NaCN (C) CH,MgBr (D) (C&Hs;)3PCH2 nowledge Required: The factors that control whether 1.2-addition or 1,4-addition is the major mode of action of nucleophiles with ?,?-unsaturated carbonyl compounds. hinking it Through: Methyl vinyl ketone is a conjugated ketone and may undergo either 1,.2-addition or 1,4 ddition with nucleophiles. Kinetically, 1,2-additions are favored over 1,4-additions. When the nucleophile is rongly basic, the initial1,2-addition is irreversible and the1,2-addition product is the dominant product. However, hen the nucleophile is less basic, the initial 1,2-addition is reversible and the thermodynamically more stable 1,4- dition product is the dominant product. The reagents in choices (A), (C) and (D) are strongly basic and give ostly 1,2-addition. The cyanide ion, in choice (B), is a much weaker base (pK, 9 for HCN) and gives edominantly 1,4-addition. Choice (B) is the correct answer. 75Explanation / Answer
The answer with appropiriate explanation is given in the question itself.
Answer is option (B) NaCN.
NaCN is a weak base and rest three are strong base. So, NaCN will add 1,4-addition fashion.
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