source : Ajit

Chemical properties-

1. Addition reactions of Acetone :

a) Addition of H2—-

i) Ketones are reduced to secondary alcohol.Reduction is carried out with LiAlH4/ether, H2/Pd , H2/Ni etc.

>C=O +H2 —->   >CHOH

CH3COCH3 + H2——> CH3CHOHCH3 (secondary alcohol)

ii) Clemenson’s reduction-

 When ketones are reduced with Zn-Hg/HCl then alkanes are formed.In this reaction >C=O is reduced to >CH2 group.

>C=O +4[H] —->   >CH2 +H2O

CH3COCH3 +4[H]——–> CH3CH2CH3 (propane) +H2O

b) Addition of HCN

Ketones on addition with  [NaCN & H2SO4] or HCN give cyanohydrins.

>C=O +HCN—–>    >C(OH) CN

(CH3)2C=O+ HCN—–>   ( CH3)2-C(OH) CN  [acetone cyanohydrin]

c) Addition of NaHSO3

form crystalline Sodium bisulphite  compound.

>C=O + NaHSO3 —–>    >C(OH) SO3Na

(CH3)2C=O + NaHSO3—->( CH3 )2C(OH) SO3Na  [ Acetone Sodium bisulphite  compound

d) Addition of Grignard reagent

Form addition product  which on hydrolysis give secondary alcohol (only formaldehyde gives primary alcohol).

>C=O +RMgX —–>   >C(OMgX) R——–>   >C(OH) R [sec.alcohol]

(CH3)2C=O + CH3MgBr —–>   (CH3)3 C- (OMgBr) ——–>   (CH3)3C-OH [tertiary alcohol] +Mg(OH) Br

2) Substitution reaction of Acetone –

a) Reaction with Hydroxylamine

                 Oximes are formed.

>C=O + H2NOH——->       >C=NOH [oxime] +H2O

(CH3)2C=O + H2NOH——->       (CH3)2C=NOH [Acetone oxime]+H2O

b) Reaction with Hydrazene

 Hydrazones are formed.

C=O + H2NNH2——->       >C=NNH2 [Hydrazone] +H2O

(CH3)2C=O + H2NNH2——->       (CH3)2C=NNH2 [Acetone hydrazone ] + H2O

c)  Reaction with Phenyl Hydrazene

 Phenyl Hydrazones are formed.

>C=O + H2NNHC6H5 ——->       >C=NNHC6H5 [  Phenyl Hydrazone] +H2O

(CH3)2C=O + H2NNHC6H5——->  (CH3)2C=NNHC6H5 [Acetone Phenyl  hydrazone] +H2O

d)  Reaction with Semicarbazide

Semicarbazones are formed.

>C=O + H2NNHCONH2——->       >C=NNHCONH2 [  Semicarbazone] +H2O

(CH3)2C=O+ H2NNHCONH2  —–>  (CH3)2C=NNHCONH2 [Acetone Semicarbazone] +H2O

e) Reaction with Phosphorous pentachloride

 Alkylidene dichloride is formed.

>C=O + PCl5  ——>   >CCl2 +POCl3

(CH3)2C=O + PCl5  ——>   (CH3)2CCl2 [iso propylidene dichloride] +POCl3

f) Reaction with Thioalcohol

Mercaptol  is formed.

>C=O + 2RSH ——>   >C(SR)2 + H2O

(CH3)2C=O + C2H5SH ——>   (CH3)2C(SC2H5)2 [Mercaptol ] +H2O

3) Haloform reaction

Acetaldehyde , acetone & other methyl ketones give haloform reaction.This is a characteristic test of CH3CO- group.For this reaction NaOH +I2 or Na2CO3 +I2 is used which produces yellow solid i.e iodoform. Similarly Chloroform is formed with Cl2 +NaOH & Bromoform with Br2 +NaOH.

CH3COCH3 + 3Cl2 +3NaOH—->  CClCO CH3 + 3NaCl +3H2O

CClCO CH3 + NaOH            ——->  CHCl3 + CH3COONa

Equation as a whole,

CH3CO CH3 +  3Cl2  + 4 NaOH—–>   CHCl3 + CH3COONa +3NaCl +3H2O