New synthesis of Phenyl-2-propanones

Phenyl-2-propanone [Tet Lett 29(24), 2977-2978 (1988)]

To a stirred solution of 2-nitropropene (0.1 mol, 8.7g) in dry CH2Cl2 (300ml) was 
added benzene (0.5 mol, 39g) at room temperature. Titanium tetrachloride (0.1 mol, 
19g) was then added dropwise into the mixture with stirring at the same temperature. 
After being stirred for 60 min (or when the starting material completely disappears 
on TLC), water (150 ml) was added and the resultant heterogenous mixture was stirred 
at reflux for 2h. The organic phase was separated, the aqueous phase extracted with 
CH2Cl2, and the pooled organic extracts washed with 1M Na2CO3 solution and dried over 
MgSO4. Evaporation of the solvent followed by vacuum distillation (bp 100-101°C at 
14mmHg) afforded Phenyl-2-propanone (ca 9g, 70% of theory).


2-nitropropene can be bought, or synthesized as outlined below:

2-Nitropropanol [JACS 67, 205 (1945)]

75.1g Nitroethane, 0.3g calcium hydroxide and 80g 40% formaldehyde solution was dissolved 
in 75ml ethanol with stirring and was allowed to stand for 48h at room temperature. 
Distillation at 100-105°C/13 mmHg (85-86°C/6 mmHg, 99°C/10 mmHg) gave 48g 2-nitropropanol 
(46%) and 14.3g of 2-nitro-2-methyl-1,3-propanediol, the latter remained as a crystalline 
residue in the distillation flask after distillation of the 2-nitropropanol. 

2-Nitropropyl acetate [Ind Eng Chem 32, 34 (1940)]

105 grams of 2-nitropropanol (1 mol) was placed in a 250ml two-necked RB flask equipped 
with a reflux condenser and an addition funnel, and 110g of acetic anhydride (1.078 mol) 
was added dropwise with good stirring. The solution was then refluxed for 30 minutes, 
cooled and poured into 200ml cold water, the organic phase separated and washed with 100ml 
water, and then vacuum distilled (bp ca 100°C at 10 mmHg, yield 90%+). The acetate is a 
clear water-white liquid with a faint, slightly mustardlike odor, almost insoluble in water. 

2-Nitropropene [JOC 15, 8 (1950)]

Sodium carbonate (0.25 mol, 14.5g) is added to a solution of 2-nitropropyl acetate
(0.5 mol, 73.5g) dissolved in 50ml benzene and refluxed in a RB flask for six hours. 
The flask is cooled and the product decanted from the solids. The residue (consisting 
of sodium acetate) is extracted with 50 ml benzene, dissolved in 100ml water, and the 
solution extracted with 3x25ml benzene. The pooled organic extracts are dried over 
anhydrous MgSO4, and the mixture fractionally distilled to afford 2-nitropropene 
(bp 57°C at 100 mmHg). 