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Chapter: Organic Chemistry: Aldehydes and ketones

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Preparation of Aldehydes and ketones

Functional group transformations allow the conversion of a functional group to an aldehyde or a ketone without affecting the carbon skeleton of the molecule.

PREPARATION

Key Notes

Functional group transformations

Functional group transformations allow the conversion of a functional group to an aldehyde or a ketone without affecting the carbon skeleton of the molecule. Aldehydes can be synthesized by the oxidation of primary alcohols, or by the reduction of esters, acid chlorides, or nitriles. Ketones can be synthesized by the oxidation of secondary alcohols. Methyl ketones can be synthesized from terminal alkynes.

C–C Bond formation

Reactions  which  result  in  the  formation  of  aldehydes  and  ketones  by carbon–carbon  bond  formation  are  useful  in  the  construction  of  more complex carbon skeletons from simple starting materials. Ketones can be synthesized  from  the  reaction  of  acid  chlorides  with  organocuprate reagents, or from the reaction of nitriles with a Grignard or organolithium reagent.  Aromatic  ketones  can  be  synthesized  by  the  Friedel–Crafts acylation of an aromatic ring.

C–C Bond cleavage

Aldehydes and ketones can be obtained from the ozonolysis of suitably substituted alkenes.

 

Functional group transformations

Functional group transformations allow the conversion of a functional group to an aldehyde or a ketone without affecting the carbon skeleton of the molecule.

Aldehydes can be synthesized by the oxidation of primary alcohols, or by the reduction of esters, acid chlorides, or nitriles. Since nitriles can be obtained from alkyl halides, this is a way of adding an aldehyde unit (CHO) to an alkyl halide (Fig. 1).


Ketones can be synthesized by the oxidation of secondary alcohols.

Methyl ketones can be synthesized from terminal alkynes.

C–C Bond formation

Reactions  which  result  in  the  formation  of  ketones  by  carbon–carbon  bond formation are extremely important because they can be used to construct complex carbon skeletons from simple starting materials. Ketones can be synthesized from the reaction of acid chlorides with organocuprate reagents, or from the reaction of nitriles with a Grignard or organolithium reagent. Aromatic ketones can be synthesized by the Friedel–Crafts acylation of an aromatic ring.

C–C Bond cleavage

Aldehydes and ketones can be obtained from the ozonolysis  of suitably substituted alkenes.

 

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