Newsgroups: alt.drugs.chemistry From: [an 263690] at [anon.penet.fi] (DM3) Date: Sat, 2 Dec 1995 23:46:06 UTC Subject: Synthesis of Nitroethane From Kornblum and Ungande, Organic Syntheses, v.38, p.75, 1958 we take the synthesis of silver nitrite as our initial step. Under yellow photograhic light prepare a solution of 76 g (1.1 mol) of sodium nitrite in 250 ml water in a 1 L flask. Prepare a solution of 169.9 g of silver nitrate (1 mol) in 500 mL water. Slowly add the silver salt solution to the sodium nitrite solution with vigorous stirring. After addition is complete, cease stirring and allow the mixture to stand in the dark for 1 hour. A yellow precipitate will form. This is filtered with suction, collected, suspended in 250 ml fresh water, and filtered again. Repeat this washing again, collecting the solid after filtering. Dry the product to constant weight in a vacuum dessicator over KOH pellets. [Note: This means to place the pellets in the bottom of the dessicator, preferably in a glass dish. The ceramic stand on which the sample is supported is put in place and the product, spread thinly on a glass plate, is placed on the support. It does *not* mean to pour the product over KOH pellets. Vacuum is maintained on the desiccator during the drying period. Drying to constant weight means that you weigh the product, dry longer, weigh again, dry longer, weigh again, and so on until two consecutive weights agree closely; i.e., in the last decimal place to which your balance will weigh.] The drying may be hastened by washing the product once with methanol after the two water washings. Should yield about 134 g (87%). Store in a brown glass bottle and place in a dark storage area until ready to use. Kornblum, et al, in J. Amer. Chem. Soc. 78, 1497, 1956 showed that alkali nitrites, especially sodium nitrite, can be used in the preparation of nitro compounds if DMF was used as the solvent. Thus, if DMF is available, the silver nitrite synthesis may be omitted. Use 1-iodoethane dissolved in DMF and add excess sodium nitrite in DMF with vigorous stirring at 0 C. Stir for 2.5 hours until reaction is complete. If 1-bromoethane is used, stir for 6 hours. Yields 60%. Using the silver nitrite method, cool 100 g of silver nitrite (0.65 mol) in 150 ml of dry ether to 0 C in a 3 neck 500 ml flask(again in a darkened room or using yellow light). Drop in 1-iodoethane (or 1-bromoethane) over a 2 hour period while stirring constantly and maintaining 0 C and dark conditions. Note that 0.65 mol of the silver salt is used so 0.50 mol of the halo-ethane should be used. Stir for 24 hours at 0 C, then 36+/-12 hours at room temperature. [Note: If the bromo is used, stirring for 48+/-12 hours at room temperature is necessary] Use the Beilstein test for halogens. The reaction is complete when no halogen is detected. [Drop a few drops of the reactant solution into a test tube containing an alcoholic solution of silver nitrate and note if a precipitate occurs. If so, the reaction is not complete. The Beilstein test uses a small coil of copper wire in a test tube. A small portion of the reactant solution is added and it is noted if reaction occurs. Silver will replace the copper. The first test is quicker and easier to perform] Silver iodide (or bromide) will precipitate over this time. Filter off the silver salt, washing with several portions of ether. Evaporate (and recover if possible) the ether at room temperature. [This may be replaced with distillation of the ether, using a water bath, at atmospheric pressure. A 2x45 cm column packed with 4 mm pyrex helices is used. The residue is distilled at 5 mm. A more efficient column is not used due to the instability of the nitrite of ethane. Maintain anhydrous conditions since the nitrite ester will hydrolze to the alcohol and will be difficult to separate.] Then distill the product at 5 mm. The nitrite of ethane will be the initial fraction, followed by an intermediate fraction, then the nitroethane will boil over. Produces about 83%. An alternate method is to boil ethane with nitric acid, but I have no details for this and it sounds as if it would be extremely dangerous. This synthesis (the silver nitrite one) is general for 1-halo-n-alkanes (straight chain alkanes). Thus nitromethane, nitropropane, etc. may be produced using this technique. The times required for reaction are also general to the synthesis so no modifications in reaction times are necessary. --****ATTENTION****--****ATTENTION****--****ATTENTION****--***ATTENTION*** Your e-mail reply to this message WILL be *automatically* ANONYMIZED. Please, report inappropriate use to [a--u--e] at [anon.penet.fi] For information (incl. non-anon reply) write to [h--p] at [anon.penet.fi] If you have any problems, address them to [a--m--n] at [anon.penet.fi]