2,4-DINITRO-5-FLUOROTOLUENE synthesis

Yield: 71%

Reaction Conditions:

with sulfuric acid;nitric acid at 0 - 30;Green chemistry;Industrial scale;

Steps:

1 Preparation of 1-fluoro-5-methyl-2,4-dinitro-benzene [Formula III, Wherein R3 is F]
Nitric Acid 67% (about 250 mL, 5.6 mol) is charged to a 3-necked round bottomed flask equipped with mechanical stirrer at a temperature of about 25-30° C. Concentrated sulfuric acid (about 360 mL. 6.75 mol) is thereafter added drop wise at about 0° C. over a period of about 30 minutes.
To the obtained nitration mixture, 1-fluoro-3-methyl-benzene [Formula II, wherein R3 is F] (about 100 mL, 0.9 mol) is added drop wise at a temperature ranging about 10-20° C. over a period of about 20 minutes.
The resulting reaction mixture is allowed to stir at a temperature ranging about 20-25° C. over a period of about 30 minutes.
Completion of the reaction is monitored by Thin layer Chromatography (TLC).
Thereafter, the reaction mixture is poured into crushed ice (about 3.0 L) to precipitate the product.
The precipitated product is filtered and dried under vacuum (for about 2 hours).
The product obtained is suspended in n-heptane (about 1.0 L) for a wash and filtered.
The same heptane wash (about 2*1.0 L) is repeated about twice to remove non polar impurities.
The product [1-fluoro-5-methyl-2,4-dinitro-benzene] (about 129 g, 71%) obtained upon filtration is taken to next step. ¹H NMR (DMSO-d₆, 300 MHz): 2.63 (s, 3H), 7.86 (d, J=12.0 Hz, 1H), 8.74 (d, J=6.9 Hz, 1H).

References:

ANTHEM BIOSCIENCES PVT.LTD;PUTHIAPARAMPIL, TOM THOMAS;SAMBASIVAM, GANESH;GOVINDA, RAJULU GAVARA;KORAMANGALA, RAVINDRA CHANDRAPPA US2014/364613, 2014, A1 Location in patent:Paragraph 0101; 0102; 0103