Acidities of some compounds with sulfur and phosphorus substituents

SECTION 7.2. CARD ANIONS STABILIZED BY FUNCTIONAL GROUPS 

The question of which resonance structure is the principal contributor has been a point of considerable discussion. Since the nonpolar ylene resonance structures have ten electrons at the phosphorus or sulfur atom, these structures imply participation of 

Johnson, Ylid Chemistry, Academic Press, New York, 1966. 

J-orbitals on the heteroatoms. Recent structural studies indicate that the dipolar ylide structure is probably the main contributor.  

The ylides are formed by deprotonation of the corresponding onium salts. The stability of the resulting neutral species is increased by substituent groups that can help to stabilize the resulting electron-rich carbon center. Phosphonium salts 

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Table 6.10. Acidities of Some Compounds with Sulfur and Phosphorus Substituents...

Acidities of some compounds with sulfur and phosphorus substituents... 

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