20 



IMMUNO-CATALYSIS 



In the above reaction, ethoxyl ion functions as basic catalyst and 

 removes a hydrogen from acetone making it electron rich (anion of 

 acetone). This ion attacks the carbonyl carbon of the ester forming a 

 new carbon to carbon bond. 



CH2C — CH3 



II 

 O 



CH3— C— O— CH2CH3 



vini — 



IQI 



CH3— G— CH2C— CH3 + CH3— CHzO" 



II II 



o o 



Acetyl acetone Ethoxyl ion 



The pair of electrons on the oxygen of the carbonyl carbon will dis- 

 place the ethoxyl group regenerating a new ethoxyl ion which can 

 function as catalyst. 



e. Acid Catalysis of Condensation Reactions. In the acid catalysis 

 of the above condensation reactions, the same products are obtained, 

 as shown in the following equations. 



GH3 — C— OCH2CH3" 

 II 



o 



H+ 



CH3 — C — OCH2CH3 

 11 

 lOH 



-> CH3C— OCH2CH3 



I 

 lOH 



CH3 C ^ 0x12"^ 



-^ CH3 — G — CH2 

 II 

 10— H 



CH3— C+— OCH2CH3 + H2C— C— CH3 



I u 



IQH +QH 



(^OCHsCHa 

 CH3 — C — CH2 — C — GHs 



I") I!) 



IQ— H |0— H 



— )► CH3C— CH2— C— GHs + GH3GH2OH + H+ 



II II 



o o 



In the acid catalysis the H+ will attach itself to one of the lone 

 pairs of the carbonyl oxygen of the ester thus making it positively 

 charged, which in turn draws out one pair of the double bond electrons 

 of the carbon and oxygen bond thus rendering the carbon electron 

 deficient and vulnerable to attack by the electron-rich methylene group 

 of the acetone molecule. 



