ALDOL CONDENSATION

ALDOL CONDENSATION:::  

                                                                               under the influence of dilute base or dilute acid ,two molecules of  an aldehyde or ketone may combine to form a beta -hydroxyldehyde or a beta hydroxylketone .The reaction is called ALDOL CONDENSATION.

 

If the aldehyde or ketone is not  having an alpha hydrogen, a simple aldol condensation will not take place.

For example:   

                                  C6H5CHO

                                        HCHO                  

                              (CH3)3CCHO 

                               C6H5COC6H5

ALL THESE COMPUND ON REACTION WITH DIL. OH DOES NOT GIVE ANY REACTION.

 

 

 

(2)   In concentration base s , these may undergo the CANNIJARO's reaction. generally the aldol  condensation are reversible. however, the equilibrium in the ketone lies far towards the left and is unfavourable to aldol condensation. However diacetone alcohol may be obtained in excellent yield  using BARIUM HYDROXIDE as catalyst in a soxhlet extractor flask through which hot acetone is allowed to percolate . the aldol product thus accumulating in the soxhlet extractor flask is kept cut of  contact with the catalyst so that it may not give back acetone.

 

 

(3) furthermore, the aldols are usually unstable. On heating as such or under  the influence of mineral acid or base, these aldols undergo dehydration to form  alpha, beta -unsaturated aldehydes or ketones.

(!)  CH3CH(OH)CH2CHO ------------------------>    CH3CH=CHCHO + H2O

(!)  (CH3)2C(OH)CH2COCH3 ------------------>     (CH3)2=CHCOCH3

 U WILL ALSO GET EXPLANATION ON ALL OGANIC REACTIONS  ALONG WITH GUIDING VIDEO LECTURES... IN THE FURTHER POSTS...

 

 

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