April 5, 1956 THESYNTHESIS OF ALIPHATICNITRO COMPOUNDS 1497 The Reaction of Ethyl Nitroacetate with Sodium Nitrite.- nitrite reaction. The ratio of masses 30 to 44 was found to A 200-1111. flask was equipped with a stirrer, a dropping be 0.303 for the nitroacetate reaction gases and 0.300 for the funnel, a thermometer and a condenser. The condenser nitrous oxide sample. exit was connected to two traps arranged in series and TABLEI cooled to ca. -70". The outlet of the second trap was attached to a 1500-ml. gas buret, filled with 20% aqueous GASEOUSPRODUCTS FORMED ON TREATMENTWITH NaNOz sodium chloride. The system was swept with carbon di- Ty)., oxide for 2 hours then 13.3 g. (0.1 mole) of ethyl nitroacetate Compound Method C. % Cot 5% Nx0 % Na in 51.9 g. of ethanol was placed in the flask and, with stir- OZNCH2COzEt Orsat 28 =!z 5 38.3 33.0 28.7 ring, a solution of 17.8 g. (0.25 mole) of 97% sodium nitrite Mass spec. 29 & 1" . .b 59.3 40.7 in 51.9 g. of water was added dropwise. Addition was in- 02NCH2COtEt terrupted after 30 minutes when about 0.1 mole of the so- OzNCH2CO~EtCOrsat 28 + 1 ..b 64.0 36.0 dium nitrite had been added; the reaction became exother- OzNCH~COzEtc Mass spec. 28 + 1 .b 65.1 34.9 mic with the liberation of much gas and exte;nal cooling BrCHZCOzEt Orsat 29 i 1 28.2 40.5 30.7 was needed to keep the temperature at 28 zk 5 . After 24 hours the evolution of gas had almost ceased; the remainder Except for 10 min. at 78". * Contacted for 24 hours with of the sodium nitrite was added but almost no additional gas 50% aqueous potassium hydroxide before analysis. e These was evolved. Gas evolution ceased altogether after a total two analyses are for the same sample of gas. of 31 hours when 2102 ml. (0.094 mole) had been collected The Lepercq Reaction.l*-In the early stages of this study (after correction to standard conditions). The gas evolved ethyl a-oximinopropionate, butyrate, valerate and caproate was colorless and odorless and no brown fumes were observed were prepared from the corresponding a-bromoesters in 71 when a sample was mixed with air; the cold traps had only to 85% yields by allowing 0.1 mole of the bromoester to re- traces of moisture. Thus hydrogen cyanide, nitrogen di- act with 0.25 mole of sodium nitrite in aqueous ethanol (50- oxide and nitrogen trioxide were absent, or present only in 55 weight per cent. ethanol) for 16 days. traces. Ethyl Nitritoacetate.-Ethyl glycolate (41.6 g., 0.4 mole, Samples of the gas were analyzed in an Orsat apparatus nm~1.4170) was treated with 39.3 g. (0.6 mole) of nitrosyl using absolute ethanol for absorption of the nitrous oxide. chloride in the presence of 50 g. (0.85 mole) of anhydrous Oxygen, carbon monoxide and nitric oxide were absent, or trimethylamine at 0' in a system protected from atmospheric present only in small amount but carbon dioxide (a correc- moisture. Anhydrous ether was added from time to time to tion having been made for the volume of COZinitially pres- keep the solution from becoming too viscous due to the pre- ent), nitrous oxiae and nitrogen (by difference) were present cipitation of trimethylammonium chloride. After the addi- in roughly equal volumes (Table I). In order to obtain a tion was completed, the mixture was stirred for another hour more direct identification of the nitrous oxide and nitrogen, and then filtered rapidly using anhydrous ether to aid in the samples were allowed to stand with 50% aqueous potassium transfer. Most of the ether was removed by distillation at hydroxide for 24 hours (samples so treated showed no carbon room temperature under reduced pressure; the residual dioxide by Orsat analysis). The carbon dioxide-free samples solution was dried over Drierite at 0 to 5" in the dark and were then dried with potassium hydroxide pellets and with fractionated. There was obtained 13.4 g. (39% yield) of Ascarite. Mass spectrometric measurements showed the ethyl nitritoacetate, b.p. 32-33' at 7 mm. and 118' at 760 significant masses to be 28 (nitrogen), 30 (nitrosyl ion) and mm. (micro-Emich), ZmD 1.4050, dz04 1.1148, d", 1.0947. 41 (nitrous oxide). Small masses were also detected at 29, Anal. Calcd. for C4H7OaiY: C, 36.09; H, 5.30; N, 10.52. 31,32,40,45 and 46; these are thought to have been due to Found: C, 36.07; H, 5.17; h-, 10.62. the natural occurrence of heavy nitrogen atoms and also to Ethyl nitritoacetate proves to be a pale, yellow-green slight contamination by air. In order to establish that the liquid which is water soluble and which hydrolyzes within a mass 30 species was due to the presence of nitrous oxide, few seconds at room temperature to give ethyl glycolate and presumably because of the formation of nitrosyl ion (NO+), nitrous acid. It is soluble in ethanol, acetone, ether, ben- a sample of nitrous oxide (Matheson) was treated with po- zene and petroleum ether. tassium hydroxide solution, dried and analyzed in the same m3nner as gas samples from the ethyl nitroacetate-sodium LAFAYETTE,ISDIANA [CONTRIBUTIONFROM THE DEPARTMENTOF CHEMISTRY,PURDUE UNIVERSITY] A New Method for the Synthesis of Aliphatic Nitro Compounds',2 BY NATHANKORNBLUM, HAROLD 0. LARSON,ROBERT K. BLACKWOOD,DAVID D. MOOBERRY,EUGENE P. OLIVETOAND GALENE. GRAHAM RECEIVEDSEPTEMBER 8, 1955 A simple new synthesis of primary and secondary nitro compounds which involves treating alkyl halides with sodium nitrite in dimethylformamide is described; 5542% yields of pure nitro compounds are obtained. To date the principal method of preparing nitro- only for the synthesis of primary nitroparaffins. paraffins has been the reaction of an alkyl halide With secondary halides the yields of nitroparaffins with silver nitrite.a A recent study has demon- are about 15y0 while with tertiary halides they fall strated, however, that this reaction is really useful to 0-5%.* A synthesis developed by Iffland and (1) Paper XI1 in the series, "The Chemistry of Aliphatic and Ali- his co-workers, which involves the conversion of cyclic Nitrocompounds." A preliminary account of this work ap- ketones into secondary nitroparaffins, is extremely peared in Chemistry and Induslry, 443 (1955). valuable in certain instances, e.g., the synthesis of (2) This research was supported, in part, by grants from The Ex- nitrocyclobutane, but it cannot be regarded as a plosives Department of E. I. du Pont de Nemours and Co.. and, in part, by the United States Air Force under Contract No. AF 18(600)- method of general ~tility.~ 310 monitored by the Office of Scientific Research, Air Research and (4) N. Kornblum. B. Taub and H. E. Ungnade, Tars JOURNAL, 76, Development Command. 3209 (1954); N. Kornblum, R. A. Smiley, H. E. Ungnade, A. M. (3) Industrially, of course, the vapor phase nitration process due to White, B. Taub and S. A. Herbert, ibrd., 77, 5528 (1955). Hass is employed on a large scale for the preparation of nitromethane, (5) D. C. Iffland, G. X. Criner, M. Koral, F. J. Lotspeicb, 2. B. nitroethane and the two nitropropanes. But despite its great com- Papanastassiou and S. M. White, ibid., 76, 4044 (1953); D. C. If- mercial importance this cannot be regarded as a laboratory procedure, Band and G. X. Criner, ibid., 71, 4017 (1953); D. C. Iffland and Teh-Fu especially since curnplcs mixtures of products are formed. Yen, ibid., 76, 4083 (1964). .% rather obvious way of synthesizing nitroparaf- X second reason for using DMF is that the reac- fins would appear to be the reaction of an alkyl hal- tion of alkali nitrites with alkyl halides is exception- ide with sodium nitrite ally fast in this inediuiri.",'? This great speed of R--S + SaSO. --+ R-SO: + SaS reaction in DXF inzil;es it 1)imihle to ininimize a Howi-er, it is widely acceptctl that the reaction of side reaction (l), whnse esistciice 1r:is lxcn estab- dkyl halides with alkali metal nitrites produces ni- lished recentlyI3 trite esters rather than nitro cotnpounds.6 R' R' To add to the confusion, there is an old and well known preparatiim of nitromethane (35-3STh yield) in which the sodium salt of chloroacetic acid is treated with sntlitini nitrite after which the un- R' stable a-nitroncetic acid is tlecarbo~ylated.~IVhat is not so well known, however, is that this method, which is clue to Kolbe,is worthless for the prepara- s0 tion of higher nitroparatlins.3 Firinlly, the reaction R = alkyl; I<' = :ilkyl or Iiytlrogcii of sulfonate esters with alkali metal nitritcs has been reported, tiine and again, to be without merit Even in DlIF socliuiri nitrite has ;I ixtlier liiiiitetl :IS :L means of synthesizing nitro par nil in^.^ solubility arid this pr rits realization of the rc;ic- The present investigation shows that, contrary tion of nitrite ion with :in xIIiy1 h:iIitIc :it r:itrb to general opinion, the reactioti of sotliuni nitrite which would fx, Liirticil):i.te(l fro111 the kixetics ill with alkyl halides is a simple and effective way of dilute solution. I1 Solietheless, the reaction of :L obtaining nitro coilipountls. The usefulness of primary broinidc or iotlitle Jvith so:liulil nitrite at this reaction can be gauged from the yields of pure room teinperatttre is so much faster than the coni- alip1i:itic and alicyclic nitro compounds given in peting process that merely working up the re:iction 'rLlbiert niisture proiiiptly prevents ititrusioii b!.