How to make Nitromethane?
I need to know how to make some for my A2 chem class, an ideas, wikipedia anit much help.
Answer:
Nitromethane is prepared by reacting sodium chloroacetate with sodium nitrite in aqueous solution :
CH2ClCOONa + NaNO2 + H2O >> CH3NO2 + NaCl + NaHCO3
The chloroacetate route is very interesting. Looks like a classic type of substitution and decarboxylation with reversed polarity at the alpha carbon compared to the acetoacetic ester synthesis.
I think Dr. A meant CH3NO2 for the first product.
Please be careful as nitromethane has been known to explode during distillation. You might want to consider your reaction conditions, workup procedures, and isolation and purification methods very carefully.
Nitromethane is prepared by reacting sodium chloroacetate with sodium nitrite in aqueous solution.
CH2ClCOONa + NaNO2 + H2O → CH3NO2 + NaCl + NaHCO3
Nitromethane is distilled from the reaction and then dried over a mild desiccant.
Another Procedure :
To a mixture of 500 g. (5.3 moles) of chloroacetic acid and 500 g. of cracked ice, is added, with stirring, just sufficient cold 40 per cent sodium hydroxide solution to make the solution faintly alkaline to phenolphthalein. About 360 cc. is required; the temperature should not rise above 20° . The solution is then mixed with 365 g. (5.3 moles) of sodium nitrite dissolved in 500 cc. of water and heated in a 3-l. round-bottomed flask fitted with a two-holed stopper containing a bent tube of large diameter connecting with an efficient condenser (set downward for distillation) and a thermometer dipping into the liquid. The receiver should be so arranged that it can be cooled, if necessary, by a stream of water.
The solution is heated slowly until the first appearance of bubbles of carbon dioxide, which occurs when the temperature has reached about 80°. The flame is then removed and the reaction allowed to proceed by itself. If no rise in temperature occurs, heat is very cautiously applied until the temperature rises to 85°, when the flame is again removed . At this temperature the exothermic decomposition of the sodium nitroacetate becomes so rapid that the temperature rises almost to 100° without further application of external heat. If heat is applied after the temperature of the liquid reaches 85°, violent frothing will occur, with serious loss of nitromethane. If the reaction becomes too vigorous it may be checked by applying a wet towel to the flask. Nitromethane starts to distil over at about 90°. During the spontaneous heating, about 120 cc. of nitromethane distils over, accompanied by about 170 cc. of water. This water is saved for redistillation.
When the mixture ceases to maintain its temperature spontaneously at 95–100°, heat is applied cautiously until the temperature reaches 110°. About 13 cc. of nitromethane and 200 cc. of water distil over. Further distillation gives water which contains too little nitromethane to pay for recovery. At this point enough sodium chloride and sodium carbonate have separated to cause serious bumping.
The water separated from the nitromethane distillates is mixed with one-fourth of its weight of salt, and redistilled, yielding 10–12 cc. of nitromethane and about 100 cc. of water. This water on distillation gives 3–4 cc. of nitromethane and about 45 cc. of water.
The total yield of moist product is 125–135 g.; on drying with a little calcium chloride and distilling, 115–125 g. of pure nitromethane, boiling at 98–101°, is obtained (35–38 per cent of the theoretical amount). A small forerun distils over below 98°, and a little dark brown residue remains.
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