Flat bottom flask with 500 ml capacity is filled with 63g (1 mol) of 99% nitric acid and placed on ice bath, then 102g (1 mol) of acetic anhydride is added by small portions with efficient stirring, not allowing temperature to rise above 10C (#1). After all nitric acid is added, neck of the flask is thoroughly dried with bath towel and flask is capped with small glass turned upside down. Mixture is allowed to stand in ice bath until it will heat up to room temperature, then reaction flask is removed from water bath and allowed to stand at room temperature for 7 days (#2). Mixture is poured to 600 ml of cold water, carefully stirred and heavy oily layer of tetranitromethane is separated in separation funnel. Crude product is washed with pure water until acid-free, with 15 ml of 40% sulfuric acid and then dried by careful washing with 10 ml of concentrated H2SO4 (#3), to get about 18 ml (29g) of pure tetranitromethane with melting point at 13.9C. Yield is ~60% from theory (#4).

1. Temperature of reaction mixture must be kept below 10C at all times (above this temperature reaction speed up greatly). Reaction at the beginning of addition is strongly exothermic and acetic anhydride must be added by small portions (0.5 ml). Then about 10 ml of acetic anhydride is added, exotherm is reduced and portions can be slowly increased from 1 to 10 ml. After addition is complete mixture must be allowed to sit in ice/water bath, slowly heating up to room temperature. If cooling during first several hours is removed, violent exothermic process can start and at 30-35C mixture must be immediately poured to emergency drain with large amount of cold water.

2. On mixture aging slow reactions takes place, at first trinitroacetic acid is formed and is decarboxylated to nitroform evolving carbon dioxide, then nitroform is slowly nitrated to form tetranitromethane. Contamination by nitroform can be clearly evidented by intense yellow coloration of water layer, then tetranitromethane is separated from reacted mixture. Different sources mention different aging periods, but 7 days at room temperature found to be most common in references.

3. Occasional batches of tetranitromethane were found to evolve considerable heat and turn black if allowed to stand over concentrated sulfuric acid for longer then 10-15 minutes. So actual contact time must be minimized, and tetranitromethane must be separated on separation funnel as soon as possible.

4. Some literature sources mention higher yields on other aging time and temperatures. Some sources mention use of catalysts and chipped glass to improve yield of this reaction, however those statements are unconfirmed in later publications.