JANUA4RY,1938
INDUSTRlAL h T D ENGINEERING CHELMISTRY
B. Oxidation of the paraffin by nitric acid, or the thermal decomposition of some unstable intermediate, gives free radicals which may react as follows: 1. Decompose to form a n olefin and a free radical of lower molecular weight which, in turn, could undergo any or all of the possible reactions of its predecessor, as R +R'
++ +
+ olefin
+ ++
R HO.NOz --+ R.NOz HO HO R'.H +R' HzO R' HO.h'Oz -+ R'.N02 HO, etc.
3. Collide with a molecule of the parent paraffin and instigate a chain reaction, as
+
R R.H --+ R.H R'+R.H+R'.H+R
or
+R
Literature Cited (3) Frey, F. E., and Hepp, H . J., I h i d . , 25, 441 (1933). (4) Hass, Hodge, and Vanderhilt, I b i d . , 28, 339-44 (1936). (5) Konowalofl', M., Ber., 26, 878 (1893); 28, 1852 (1895), 29, 2199 (1896); Chem. Zentr., 76, ( 2 ) , 818 (1905), 77 ( 2 ) , 312 (1906). (6) Markownikoff, W., Ber., 32, 1441, 1445 (1899), 35, 1584 (1902); Chem. Zentr.. 70 121. 472-3 (1899). (7) Meyer, Victor,'Ber.; 5,' 203, 399, 514, 1029, 1034 (1872), 9, 529 (1876); Ann., 175, 88 (1875), 180, 134 (1876). (8) Neuhaus and iMarek, IND.ENG.CHEni., 24, 400 (1932). (9) Pope, Dykstra, and Edgar, J. ,4m. Chem. SOC., 51, 1875, 2203 \----,-
4. Unite with another free radical to form an alkane, as R
1. Direct oxidation of the parent hydrocarbon, and/or 2. Oxidation of the nitroparaffins, and/or 3. Oxidation of free radicals, cleavage products, and olefins. (1) Calingaert, G., C'hem. Rev., 2, 43-83 (1935). ( 2 ) Frey, F. E., I m . EXG.CHEM.,26, 200 (1934).
2. Unite with a molecule of the nitrating agent t o yield a nitroparaffin and an active fragment, as then and
67
+ R' +R.R', and/or
5 . Become oxidized to carbon dioxide and water, or to some oxidized intermediates. C. The oxidation products may be accounted for by assuming:
(IO) Rice, F. O., Ibid., 53, 1959 (1931). (11) Rice, F. O., and Rice, K. K., "Aliphatic Free Radicals," Baltimore, Johns Hopkins Press, 1936. (12) Seigle, L. W., unpublished work. (13) Sickman and Allen, J . A m . Chem. SOC., 56, 1251 (1934). (14) Worstall, R . A,, -4m.Chem. J.,20, 202 (1898).
RECEIVED August 26, 1937. Abstracted from a thesis submitted t o the faculty of Purdue University b y Rush Fox McCleary in partial fulfillment of t h e requirements for t h e degree of doctor of philosophy, June, 1937. This research project was sponsored by T h e Commercial Solvents Corporation under the general supervision of H . B. H a m
Nitration of n-Pentane' H. B. H A S AND J. A. PATTERSON Purdue University, Lafayette, Ind.
The vapor-phase technic for the nitration of saturated hydrocarbons has been extended to n-pentane. The nitroparaffins thus formed are 1-nitropentane, 2nitropentane, 3-nitropentane, l-nitrobutane, 1-nitropropane, nitroethane, and nitromethane. These include all of the compounds theoretically derivable by adding a nitro group to the free radicals obtainable from pentane by loss of a hydrogen atom or by fission of a carbon-to-carbon linkage.
T
H E vaper-phase technic for the nitration of volatile saturated hydrocarbons was previously described by Hass, Hodge, and Vanderbilt, and results obtained x-ith ethane, propane, and the two butanes yere reported ( I ) . The present paper deals with a n extension of this process to n-pentane which is one of the hydrocarbons readily available in pure form from natural gas gasoline. This study may be regarded as a critical test of the freeradical theory of nitration discussed in the paper in this symposium by McCleary and Degering (page 64). Since 1 This paper, which contains material abstracted from t h e L1.S.thesis of J. A. Patterson, is the seventh in a series on the subject of syntheses from natural gas hydrocarbons. T h e others appeared in IND.ENG.C H E x . , 23, 3 5 2 ( 1 9 3 1 ) : 17,1190 ( 1 9 3 6 ) ; 28, 3 3 3 , 339, 1178 ( 1 9 3 6 ) ; 29, 1335 (1937).
excellent evidence is a t hand for the presence of each of the expected products, and there is no reason for believing that any other nitro compounds were formed, the theory must be regarded as having been confirmed a t least to some extent. Every nitroparaffin has been obtained which is theoretically derivable by adding a nitro group to the free radicals obtainable from a given hydrocarbon by loss of hydrogen or by fission of a carbon-to-carbon linkage. Thus, loss of an appropriate hydrogen atom from n-pentane can yield the radicals 1-pentyl, 2-pentyl, or 3-pentyl. Fission between carbon atoms 1 and 2 can yield the radicals butyl and methyl while n break between carbon atoms 2 and 3 can give ethyl and propyl. These radicals correspond to the nitroparaffirls actually found,which were 1-nitropentane (boiling a t 172 " C.), 2-nitropentane (boiling a t 152"+ 1' C., estimated), 3-nitropentane (boiling at 152'C.), I-nitrobutane (boiling a t 151"C.), I-nitropropane (boiling a t 131 O C.), nitroethane (boiling a t 114' C.), and nitromethane (boiling a t 101.7" C.). The literature does not record a boiling point for 2-nitropentane, but a coniparison of the boiling points of any known nonassociated derivative of pentane substituted in the 2-position with the corresponding 3-isomer shows that the boiling point of the one is never more than 1" from that of the other. Rectification of the reaction mixture can thus be relied upon for the isolation of nitromethane, nitroethane, l-nitropropane, and 1-nitropentane, while the other three compon e n t s i . e., 1-nitrobutane, 2-nitropentane, and 3-nitropentan-appear as a composite fraction. The analysis of this ternary mixture involved reduction to amines, removal by rectification of 1-aminobutane (boiling a t 76" C.) from 2-
INDUSTRIAL AND ENGINEERING CHEMISTRY
68
aminopentane (boiling at 90" C.) and 3-aminopentane (boiling at 89-91' C.). The two latter compounds were converted to the hydrochlorides, and the melting point of the hydrochloride mixture was compared to those of known mixtures of 2-aminopentane hydrochloride and 3-aminopentane hydrochloride.
VOL. 30, NO. 1
hydroxide. The resultant mixed salt was dried and destructively distilled. The ketones formed were salted out, dried, and purified. Methyl propyl ketone (boiling at 101" C.) was isolated by rectification. Seventy-five milliliters of methyl propyl ketone, a concentrated aqueous solution containing 65 grams of hydroxylamine hydrochloride, and enough ethyl alcohol t o make a homogeneous solution put in a three-neck, round-lbottom flask equipped with a mercury-seal stirrer, reflux condenser, thermometer, and dropping funnel. A strong solution containing 40 grams of sodium hydroxide was added slowly through the dropping funnel while the mixture was stirred rapidly. Stirring was continued for an hour after the addition was complete. The methyl propyl ketoxime was extracted with ether and distilled. Fifty-five milliliters of methyl propyl ketoxime were dissolved in a liter of absolute alcohol in a &liter round-bottom flask equipped with a Liebig condenser. After heating the solution on a steam cone until the alcohol started refluxing, 95 grams of sodium were added at such a rate as to keep the solution just at the boiling point. This addition took 3 hours. This reaction mixture, after removing unreaoted sodium, was steam-distilled, and then the distillate was redistilled under vacuum almost to d r y n e s s . T h e residue was made alkaline with concentrated sodium hydroxide solution and extracted with ether. The ether solution of the amine thus obtained was treated with dry hydrogen chloride in the cold, and 2-aminopentane hydrochloride was obtained. The latter was recrystallized by dissolving the salt in the smallest amount of butyl alcohol possible and then reprecipitating by the addition of ether. This precipitate was recrystallized from absolute alcohol and ether. ,4 product formed which melted a t 147.5-148' C. The melting point in the literature is 168" C. (4).
~ - 0 I. A,.0 Y
I U FIGURE 1. NITRATION APPARATUS
n-Pentane was nitrated in the vapor phase in the apparatus shown in Figure 1: The n-pentane was vaporized in flask G by a coil of resistance wire, F , which was enclosed in a U-shaped glass tube. The current passing through the resistance wire was regulated by means of a lamp bank, and thus the rate of volatilization of the pentane was controlled. The nit,ric acid was forced in a fine stream through a ca illary opening, I , directly into reaction tube H. The rate of $ow of the acid was governed by the pressure applied on the surface of the acid contained in graduated flask C. The pressure v,-as measdred by means of an open-end manometer, A , and it was found that a pressure of 18 cm. of mercury would force about 1 ml. of acid through the capillary per minute. The receiven, J , were kept immersed in an ice bath to prevent any loss of desired product through reaction with the unused nitric acid. A cold trap, K , immersed in a Dewar flask containing alcohol and solid carbon dioxide, was used to catch any product that might be carried past receivers J . The temperature at which the nitration reaction took place was controlled by immening the reaction coil in a nitrate-nitrite bath. The bath was electrically heated and the temperature controlled by a thermoregulator. The materials used were ordinary c. P. concentrated (68 per cent) nitric acid and n-pentane with a boiling range of 35-37" C. The latter was purified by washing with concentrated sulfuric acid, followed by sodium carbonate solution, and then several times with water. It was dried with calcium chloride. After this treatment the pentane did not decolorize bromine jvater. The nitration reaction was carried out at 400' C. Nitric acid was forced into the reaction tube at the rate of about 70 nil. per hour. *Pentane was volatilized at the rate of about 260 ml. per hour. The average mole ratio of pentane to nitric acid for the entire series of runs was 2.3 since a lower ratio resulted in explosions. Care was taken to avoid the brown fumes of nitrogen dioxide xhich seemed to indicate when explosive proportions were present.
Preparation of Amine Hydrochlorides In order to establish the amounts of 2- and 3-aminopentane hydrochlorides present, a melting point-composition curve was prepared from the pure compounds. 2-Aminopentane hydrochloride was prepared in the following manner: A mixture of glacial acetic acid (180 grams) and butyric acid (264 grams) was neutralized with calcium
200 0 190
d 5 r
180 170
160
150
FIGGRE 2.
CURVE
FOR
2-
COMPOSITION-MELTING POINT AND 3-AMMINOPENTANE HYDROCHLORIDES
3-Aminopentane hydrochloride was prepared in the following manner (3): Propionic acid (187 grams) was neutralized with calcium oxide. The calcium propionate formed was destructively distilled. ,4fter purification, 37 grams of 3pentanone were obtained (boiling a t 100-103" C.). Thirty-six grams of 3-pentanonel 35 grams of hydroxylamine hydrochloride, and 75 ml. of water were placed in a 2liter, three-neck flask equipped with a mechanical stirrer, a reflux condenser, a thermometer, and a dropping funnel. A solution of 25 grams of sodium carbonate in 100 ml. of water was run in at such a rate that the reaction temperature did not rise above 45" C. The solution was vigorously stirred
JANUARY, 1938
INDUSTRIAL AND ENGINEERING CHEMISTRY
during this addition. After extraction and purification, 32 grams of diethyl ketoxime were obtained.
-/I
1801
160
,
/
14d
I-NITROPENTAN
/ MXTURE OF I-NITROBUTANE 2-NITROPENTCINE 3-NITROPENTAllE
NITROETHANE
801
1
40 0
1 1 % 7.19 13 85 12 5
1-Nitropentane 2-Nitropentane 3-Nitropentane
21.6% 20.8 23.0
NITROMETHANE
$100,
6o
weighed out and mixed, and several melting points of the mixtures were taken with calibrated Fisher short-stem thermometers ( 2 ) . The curve shown in Figure 2 is the result of plotting percentage composition against average melting point. The approximate composition of material obtained by the nitration of n-pentane is as follows: Nitromethane Nitroethane 1-Kitropropane I-Nitrobutane
,,~~NITfiOPROI"~
~
69
I 80
EO
240
320 400 480 560 ML OF DISTILLATE
640
720
RECTIFICATION CURVEOF THE PRODUCT OBTAIXED B Y NITHATING PENTANE AT 400 FIGURE 3.
' c.
The diethyl ketoxirne was dissolved in 0.75 liter of absolute alcohol and reduced in the same way as its isomer. Sixty grams of sodium were necessary. The reaction mixture was steam-distilled into a hydrochloric acid solution, and the distillate was evaporated to dryness to give the crude 3-aminopentane hydrochloride. This was purified by recrystallization from absolute alcohol and then from chloroform. The salt was dissolved in these solvents and then reprecipitated by the addition of anhydrous ether. The melting point of this material was 216" C. Various samples of these two amine hydrochlorides mere
CONTACT SULFCRIC
The average yield based upon nitric acid reacting per pass was 31 per cent. As pointed out previously, the nitric acid which does not form nitroparaffins is almost wholly reduced to nitric oxide, which is easily reconverted to nitric acid by atmospheric oxidation. The over-all yields in a system involving recovery of the nitric oxide would therefore be satisfactorily high.
Acknowledgment The writers wish to thank L. W. Seigle for his aid in the preparation of this paper.
Literature Cited (1) Hass, H. B., Hodge, E. B., and Vanderbilt, B. M.,IND. ENO.
CHEM.,28,339-44 (1936). (2) Hass, H. B., and Weber, Paul, Ibid., Anal. Ed., 7, 238 (1935). (3) Marvel, C . S., Organic Syntheses, 11, 54, 58 (1931). (4) Tafel, J., Ber., 22, 1856 (1889). RECEIVEDSeptember 23, 1937,
Courtesy, du Pont Company AS ''TAKINQ THE GRAVITY"AT THE GRASSELLI PLANT O F E. I. D U PONT DE NEMOURS & COMP.4NY, PHILADELPHIA, PA.
ACID OPER.4TION
THE ALCHEMIST By Hendrick Heerschop
0 Through t h e courtesy of Sir William J. Pope, we are able t o bring a third painting b y the famous Dutch painter Hendrick Heerschop, who was born in Haarlem in 1620 and died some time prior t o 1700. This painting, No. 85 in the series of Alchemical and Historical Reproductions, purchased b y Sir William in May, 1928, is signed on the book-page, where also will be found the date, 1687. I n general style, somberness, and lack of much apparatus, this painting is similar t o t h e previous one shown (No. 51, March, 1935, page 314) and is quite different from the first one by Heerschop shown in our series (No. 42, June, 1934,page 645). We extend our hearty thanks t o Sir William for his kindness in sending a photographic negative and for his permission to reproduce this painting. Additional paintings owned by him will be shown in future issues. D. D. Berolzheimer 50 East 41st St., New York, N. Y.
Alchemical and Historical Reproductions In response to a request from those who wish the complete list t o date, the following information is given: These prints of famous paintings and engravings were started in the August, 1931,issue, and appear monthly thereafter in our volumes for the subsequent years. A complete list of the first sixty reproductions appears in our January, 1936,issue on page 129. The reproductions (Nos. 61-72) published in 1936 are listed on page 74 of our January, 1937,issue. Orders for photographic prints 8 by 10 inches at $1.50,and 16 by 20 inches at $4,specifying the numbers here indicated and titles as given, should be sent with advance payment t o D. D. Berolzheimer, 50 East 41st St., New York, N . Y. These photographs are not carried in stock, but are ordered only on receipt of remittance. Purchase of these photographs does not confer any rights of publication of these reproductions. Special arrangements must be made with Mr. Berolzheimer to obtain such rights. Prints and enlargements can be supplied in black and white only; velvet, m a t t , or glossy finish. Prints in color cannot be supplied. An additional reproduction will be published each month. The 1937 reproductions are as follows:
73. Shop of a n Alchemist, Teniers (January, page 78. 74) 74. Rumford Stove, Gillray (February, page 166) 79. 75. The Alchemist, Teniers (March, page 345) 80. 81. 76. Alchemist Lecturing on the Elixir of Life (April, 82. page 459) 77. The Alchemist, Isabey (May, page 554) 83. 84. Cherubs in the Alchemist’s
Parting Laboratory, Deutsches Museum (June’ page 710) The Alchemist, Rabinovitch (July, page 776) Der Alchimist, Schmidt (August, page 945) The Alchymist, Wijck (September, page 1039) L’Alchimiste, Poel (October, page 1134) L’Alchimiste, Brunin (November, page 1276) Workshop, Teniers
(December, page 1388)
1
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