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A study of the reaction rate of lime with water was made. The rate of reaction decreases with time of exposure of the quicklime before slaking, with an increase in the particle size of the quicklime and with an increase in the concentration of sodium carbonate in the slaking water.
Bibliography Adams, F. W., Chem. & Met. Eng., 34, 282-3 (1927). Adams, F. W., IND. ENG.CHEM.,19, 589-91 (1927). Am. SOC.Testing Materials, Standards for Lime (1939). Anable, A., and Knowles, C. L., Paper Trade J., 85, No. 1, 55-8 (1927). Bassett, Henry, J . Chem. Soc., 1934, 1270-5. Bodlander, Z . angew. Chem., 18, 1137 (1905). Bonnell, D. G. R., J . SOC.Chem. Ind., 53, 279-82T (1934). Budnikov, P. P., and Gulinova, L.,Tonind.-Ztg., 60, 889-901 (1936). Danihl, W., Flushoh, R., and May, K., Ibid., 60, 761-3 (1936). Dorr, J. V. N., and Bull, A. W., IND.ENG.CHEM.,19, 558-61 (1927). Goodwin, L. F., J. SOC.Chem. Ind., 45, 360-1T (1926). Harrup and Forrest, IND.ENQ.CHEM.,15, 362 (1923). Haslam, R. T., Adams, F. W., and Kean, R. H., Ibid., 18, 19-23 (1926). Holmes, Fink, and Mathers, Chem. & M e t . Eng., 27, 1212 (1922). Knowles, C. L., Paper Trade J . , 84, No. 14, 59-64 (1927).
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Kuznetzov, A. M., J . Chem. I n d . (V. S. S. R.),14, 1333-5 (1937). Lea, F. M., and Besaey, G. E., J. Chem. SOC.,1937, 1612-15. Lunge, Georg, Handbuch der Soda-Industrie (1916). Maune, Friedrich, Tonind.-Ztg., 61, 1049-51 (1937). Miller, L. B., and Witt, J. C., J . Phvis. Chem., 32, 285-9 (1929). Molitor, Heinrich, Asphalt Teerind. Ztg., 26, 451-3 (1926). Nada, Tokichi, and Kan, Hisao, J . SOC.Chem. Ind. Japan, 40, Suppl. Binding, 195-6 (1937). Nada, Tokichi, and Miyoshi, Akira, Ibid., 35, Suppl. Binding, 317-20 (1932). Petrov, A. V.,UkraEn. Khem. Zhur., 8, Wiss.-tech. Teil, 89-93 (1933). Picher, W. E., Chem.-Ztg., 56, 610-11 (1932). Pioer, W. E., Chem. & Met. Ena., 37, 362-5 (1930). (26A) Piper, W. E., personal comm;nication, 1932. ' Pozin, M .E., J . Chem. Ind. (U. S . S . R.), 12, 43-5 (1934). Ray, K. W . , and Mathers, C. F., IND.ENG.CHEM.,20, 475-7 (1928). Rogers, J. S., Ibid., 20, 1355-6 (1928). Shaw, W.M., MacIntire, W.H., and Underwood, J. E., Ibid., 20, 312-14 (1928). Ibid.. 20. 315-19 11928). Squire, M. E., Rock Pioducts, 39, 57-60 (1936). Stockett, Paper Ind., 17, 652-4 (1935). Ullmann, Enzyklopaedie der technischen Chemie, 2nd ed., Vol. 8, p. 60 (1931). Voronchikhin, V. E., J . Chem. I n d . Moscow, 13, 154-8 (1936). Voronchikhin, V. E., and Plathotnyuk, G. S.,Ibid., 10, 33-9 (1934). Whitman and Davis, IND. ENC.CHEM.,18, 118 (1926).
AMINATION IN LIQUID AMMONIA R . NORRIS SHREVE AND D. R. BURTSFIELD' Purdue University, Lafayette, Ind.
This paper is a continuation of the study of the action of sodium amide on alkyl halides in liquid ammonia, particularly on various amyl chlorides and bromides, as well as on n-hexyl, n-octyl, and n-dodecyl bromides, at -50' C. Amines were obtained as high as 30 to 80 per cent of the halide converted. The by-products were largely olefins, though the carbon balance was not very good owing to the difficulty in the recovery of these volatile materials, on the small scale of these experiments. With the reasonable price now prevailing for liquid ammonia and for sodium, this process promises to be an economical method of making certain amines.
T
HE reduction in cost of ammonia, together with efficient
ammonia recovery systems, has increased the possibilities of the commercial use of liquid ammonia as a reaction medium. The use of lower alkyl amines in the preparation of rubber chemicals has been important for some time. Recently the use of alkyl amines of five or six carbon atoms per molecule in the preparation of pharmaceuticals has stimulated interest for the preparation of primary alkyl amines in good yields from inexpensive intermediates. Alkyl amines have been prepared by the action of liquid ammonia upon alkyl bromides by Braun (1) who reports a yield
of 10 per cent of primary amyl amine and 80 per cent of secondary amyl amine. Octyl bromide gave approximately equal amounts of the primary and secondary amines while ndodecyl bromide gave a yield of 90 per cent of the primary amine. Recent work on the reaction between alkyl halides and sodium amide in liquid ammonia was reported by Shreve and Rothenberger (4)and shown to give a larger portion of primary amine. This work has been continued with the object of obtaining a more complete recovery of reaction products. The following over-all reactions are known t o take place: CsHllBr C6HllBr 2CsHllBr 3CaHllBr
+ C~HX + NaBr + NH3 (1) + NaNH2+ A7aNHz+CbHnNH2 + NaBr (2) + 2Na5Hz +(CsHll)t;\?TH+ 2NaBr + KH3 (3) + 3XahH2 +(CgH11)A + 3NaBr + 2"s (4)
The equations do not necessarily account for the mechanisms for the reactions. Reactions 3 and 4 have been found to be much more prominent when water is added t o the amination mixture following the usual amination process.
Experimental Procedure OF SODIUM AMIDE. About 240 ml. Of liquid ammonia were drawn from a 25-pound cylinder into a n open Dewar beaker. Only commercial grade ammonia was used. T h e liquid ammonia was then poured through a Pyrex glass funnel into a cold 500-ml. three-neck round-bottom flask which was immersed in a chloroform-carbon tetrachloride mixture containing 50 per cent chloroform b y weight and cooled b y solid carbon diPREP.4R.4TION
1
Present address, Merck and Company, Ino., Rahway, N. J.
February, 1941
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silvered strip, 1 cm. wide and running the length of the jacket, provided a means of observation of the operation of the column. The rate of removal of gases from the top of the column was adjusted by means of a clam on the rubber connecting tube to [eep the spiral in the reflux tube covered with liquid ammonia. Acetone was used as the cooling medium and was circulated by a laboratory centrifugal pump through a copper coil immersed in a chloroform-carbon tetrachloride bath containing 50 per cent by weight of chloroform and cooled by solid carbon dioxide to - 50" C. The gaseous mixture from the top of the fractionating column was conducted to the bottom of an electrically heated scrubbing tower packed with glass beads. By use of a resistance in the heating circuit the temperature of the absorption column was held about 30' C. above the boiling point of the hydrocarbon. Ten er cent hydrochloric acid containing phenolphthalein was introtuced dropwise at the top and was received at the bottom in a bottle which acted as a seal for the bottom of the tower. Exit gases from the acid tower were passed through an air condenser to remove most of the moisture and led to a lowtemperature calibrated trap. The condensing bulb and acid tower were operated under slightly less than atmospheric pressure maintained by a siphon bottle connected to the cold trap. I n cases where butylene and isoamvlene were formed. the hvdrocarbon aases were dried with calcium bhloride"before condgnsation. PREPARATION OF MATERIALFOR ANALYSIS. After removal of ammonia, the material remaining in the reaction flask was treated with a solution of 20 grams of sodium hydroxide in 120 ml. of water. The pur ose of this water was to dissolve the sodium tromide and ensure the presence of the free amine, After stirring for 3 to 4 hours in the case of the lower bromides, the organic material was extracted with four 50-ml. portions of ether. I n the case of higher bromides and all chlorides, the upper organic layer was separated and treated with an excess of concentrated hydrochloric acid. The unreacted halide was removed from the aqueous layer, and any solid amine hydrochloride was filtered from the liquid halide. Free amines were then formed by treating the combined solid hydrochlorides and aqueous acid extract with an excess of concentrated sodium hydroxide solution. This mixture was united with the first aqueous layer and then extracted with four 50-ml. portions of ether. The ether extract was dried for at least 12 hours over FIGURE 1. APPARATUS FOR AMMONIADISTILLATION AND OLEFIN sodium hvdroxide sticks. RECOVERY The dried ether soluANALY~IS OF PRODUCTS. tions of the reaction products were analyzed by rectification in a Purdue modification of a Podbielniak fractionating column described by Shreve and RothenREMOVAL OF AMMONIA. The evaporation of ammonia disberger (4). After removal of the ether, the products were solved in the organic material results in the loss of some of the collected separately in a calibrated receiver which ermitted products. Hydrocarbons of three or more carbon atoms per molecule are insoluble in liquid ammonia ( 2 ) . The amines were the volume of each fraction to be recorded to 0.1 mf. These temperature-volume distillate data were then plotted to give a se arated from ammonia and hydrocarbons by a fractionating distillation curve (Figure 2) from which the per cent yield could be coyumn, and the ammonia and hydrocarbon gases drawn from the calculated. Products which boiled much over 100' C. were disto of the column were separated by an acid scrubber. tilled at reduced pressures, and their identity was checked by the Qhe two side necks of the reaction flask were then sto pered, equation of Hass and Newton (8). and a stopper containing a ground-glass joint was placegin the IDENTIFICATION OF UNSATURATED HYDROCARBONS. The uncentral opening. The flask and contents were transferred to the saturated hydrocarbons were sometimes identified by conversion bottom of a low-temperature Podbielniak-type fractionating to the correspondin dibromides by slow addition of a 10 per cent column shown in Figure 1. This column, operating at atmoscarbon tetrachlorife solution of bromine a t -10' C. After pheric pressure, consisted of an 8-mm. Pyrex tube containing a bromination was complete, the mixture was washed with sodium Nichrome wire spiral to provide intimate contact between liquid carbonate solution and then water, and dried over calcium chloand va or. On the u per end of the reflux tube was sealed a ride. Carbon tetrachloride was distilled from the dried mixture verticafcondensing tuge, 22 mm. in diameter and 26 cm. long, and the dibromide distilled a t reduced pressure. The identity surrounded by the cooling medium. This condensing tube carof the dibromide was confirmed by calculation of its standard ried a side arm, connected t o a 500-ml. flask which acted as a gas reservoir for a mercury manometer. Inside the condensing tube boiling point by the equation given by Hass and Newton (3). was fitted a smaller gas take-off tube which extended to within 4 cm. of the lower end of the condenser tube. A +50" to -50' C. Amination of Bromides alcohol thermometer was placed inside the gas tube so that the bulb extended below the lower end of the take-off tube. The %-ALKYL BROMIDES.The amination of normal alkyl brofractionating column was placed inside a silvered vacuum jacket, mides was carried out to test the applicability of this process whose u per end was greatly enlarged to provide a cup for holding to compounds of varying molecular weight but with the the col8condensing tube fitted into the tubular portion of the bromine atom in similar position (Table I). vacuum jacket, and thus formed the bottom of the cup. An un-
oxide. A mercury seal stirrer was fitted in the central neck of the flask, while one smller opening carried a tube for holding a pentane low-temperature thermometer and a connection to a drying tube; the third opening of the flask was used for adding t h e sodium and later the alkyl halide. One half equivalent of sodium amide was prepared according to the following directions given by Vaughn, Vogt, and Nieuwland (6): 0.15 ram of ferric nitrate crystals was added and agitation started. Efeven and one half grams of sodium were added in approximately 1-gram amounts of small pieces. Enough time was allowed to elapse between sodium additions to allow conversion of each addition to the amide. The conversion of sodium to sodium amide was rapid at the boiling point of ammonia (-33" C.) and was complete in 15-20 minutes. As soon as the conversion to sodium amide was finished as indicated by the loss of the metallic blue color, the temperature was lowered to -50" C. by addition of more solid carbon dioxide to the cold bath. ADDITION OF ALKYL HALIDE. One half mole of the alkyl halide was then added dropwise from a separatory funnel to the efficiently stirred suspension of sodium amide in liquid ammonia at a rate which still enabled the temperature of the mixture to remain constant. I n the case of the lower alkyl bromides the addition required about 1.5 hours, while the chloride addition was complete in about 1 hour. This shorter time was possible because of the slower reaction rate and evolution of less heat. These amination mixtures were stirred for 2 hours following the addition of the halide and then subjected to one of two treatments for removal of the ammonia that acted as a reaction medium.
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alkyl chlorides with bromides was carried out. The reaction TABLEI. AMINATION OF n - A m Y L BROMIDESWITH SODIUM rates in these cases were much lower th'an in the amination of AMIDEAT -50' C. the corresponding bromides. I n Table I11 the conversion is (Time, 2 + 5 hours; 0.5-mole amounts; ratio of bromide t o NaNHi, 1 to 1 ) reported as that part of the chloride which was not recovered Yield of Products, % % % as the chloride from the reaction mixture. The yields, as well CqnTotal Total Amines Alky! version, AmiReas the amounts in the total recovery column, are based upon Bromide % Olefin Prim. Sec. Tert. nation coverv the fraction of the original half mole of material that undern-Butyl 100 19.1 59.1 10.9 . . . 70.0 89.1 n-Amyl 100 7.4 67.3 9.9 ... 77.2 84.6 went a change. n-Hexyla 100 10.2 74.1 ... 11.3 . . . 74.1 84.3 I n the amination of the n-alkyl bromides, complete conn-Hexyl 100 9.5 61.2 ... 82.0 n-Octyla 100 8.4 29.5 34.2 ... 72.5 63.7 72.1 version had taken place in the 2-hour amination and 5-hour n-Dodecyla 73 4.1 58.2 ... ... 58.2 62.3 recovery period, for those up to and including n-octyl broa Ammonia removed b y slow evaporation over 24 hours without fractionamide. But in the case of the n-alkyl chlorides, the reaction tion. rates were slow enough so that a difference in conversion was found in this length of time. A much higher proportion of unsaturated hydrocarbon to amines was formed from the Considerable difficulty was experienced in handling nchlorides than from the bromides. octyl and n-dodecyl bromides and n-octyl and n-dodecyl AMYLCHLORIDES.The amination of the amyl chlorides amines. The high yield of secondary n-octyl amine may was performed in hope that some of them might yield amine be caused by the presence of n-octyl bromide during the in cases where the bromides failed (Table IV). distillation of the amine. The presence of this bromide was not shown by the usual separation of amines from halides by treatment with hydrochloric acid. As only a small amount Addition of Water to Amination Mixture of n-octyl bromide was available, this was not extended. I n some aminations of alkyl bromides, water was added to n-Dodecyl bromide froze upon introduction to the liquid the amination mixture a t the end of the amination period to ammonia mixture. remove excess ammonia by solution in water. If only a It is interesting to note that the yield of primary amines insmall amount of water was added and then 200 ml. of water creases with increasing length of carbon chain for lower memwere added to dissolve the ammonia, different distribution of bers. Most noteworthy is the consistency of the results on the alkylated products was obtained. The organic and total amination. This seems to indicate that the relative aqueous layers were separated and analyzed for organic marates of the two competing reactions, amination and formation terial separately (Table V). of unsaturated hydrocarbons, are fairly constant. The formation of secondary amines is noticed more with the lower members of the series. This indicates that the reaction between Discussion of Results alkyl amines and alkyl bromides is more rapid with these The reaction between alkyl halides and a suspension of lower members. sodium amide in liquid ammonia a t atmospheric pressure and AMYLBROMIDES.I n order to test the limits of this reaction low temperature has been shown to yield olefins and amines. for producing amines having the amino group in different Primary amine is formed in highest yield of 74 per cent positions, aminations were performed using different isomeric from n-hexyl bromide. The yield of primary amine deamyl bromides. These aminations were carried out under creases with decrease in length of carbon chain accompanied similar conditions (Table 11). by an increase in higher alkylated ammonia derivatives, Thus, n-amyl bromide gave a yield of 67 per cent primary amyl amine with 10 per cent secondary amine while n-butyl TABLE 11. AMINATIONOF AMYLBROMIDES WITH SODIUM AMIDE AT -50" C. (Time, 2
+ 5 hours;
Amyl Bromide n-Amyl Isoamyl see-Amyl (2bromo entane) tert-Amy? l-Bromo-2methylbutane
0.5-mole amounts: ratio of bromide t o sodium amide, 1 t o 1) Yield of Products, % Olefin
Amines Prim. Sec.
7.4 21.6 63.2
67.3 60.2 0.0
58.5
0.0 5.5
57.5
%
%
Total Amination
Total Recovery
9.9 9.4 0.0
77.2 69.6
84.6 91.2 63.2
0.0 0.0
0.0 5.5
0.0
58.5
63.0
200 0 0
180
Y
5160 E
