terials used in this work. also acknowledged.
Its cooperation and assistance are
Plank, c. A,, Yost, c. w.9 Chem. Processing, in Press. Pruitt, M. E., Rogers, W. A., Jr. (to Dow Chemical Corp.), U.S. Patent (ALP. ~. 9. 1960). .. ..,_ - ~ 2.948.757 ~ --- ,. ._ Saunders, J. H., Frisch, K. C., “Polyurethanes, Chemistry and Technology,” Interscience, New York, 1962. Union Carbide Corp., Belgian Patent 584,738 (March 16, 1960). Yost, C. W., M. S. thesis in chemical engineering, University of Louisville, Louisville, Ky., September 1966. -I-
literature Cited Bender, R. J., “Handbook of Foamed Plastics,” Lake Publishing Corp., Libertyville, Ill., 1965. DeGroote, M. (to Petrolite Corp.), U.S. Patent 2,626,910 (Jan. 77 -.,
IC)$?)
L. G.
~
.I
-_I-
Lundsted,
(to W andotte Chemicals Corp.), U.S. Patent
RECEIVED October 28, 1966. ACCEPTED March 8, 1967
264,619 (April 6, 19547.
QUATERNIZATIONS OF TRIETHYLAMINE AND TRIETHANOLAMINE WITH EPICHLOROHYDRIN JOHN B. M c K E L V E Y , R U T H R. BENERITO, AND T R U M A N L . W A R D Southern Regional Research Laboratory, New Orleans, La. An investigation of cellulose-epoxide reactions, many of which are catalyzed by Lewis bases, necessitated a study of the reactions between epichlorohydrin and triethylamine or triethanolamine at room temperature. Preparation of the simple glycidyl quaternary chlorides has not been found to be feasible because triethylamine continues to react to form 2-hydroxytrirnethylene-l,3-bis(triethylammonium chloride), which has been isolated for the first time in good yield. The triethanolamine, while initially quaternizing with epichlorohydrin, dimerizes to form [2,5-p-dioxanylenebismethylene]bis[tris(2-hydroxyethyl)ammonium chloride], which was isolated in high yield. Physicochemical data have been used as the basis of mechanisms postulated for both reactions.
PIcHLoRoHYDRiN has found wide usage in polymer chemis-
E try because of its uniqueness in possessing both a labile
chlorine and an oxirane group. The authors’ interest has been in mechanisms of epichlorohydrin-amine reactions because of their importance in the chemical modifications of cellulose. Of particular interest are reactions catalyzed by tertiary amines. The relatively few literature reports give conflicting views of mechanisms of reactions between epichlorohydrin and triethylamine, possibly because reaction products were not isolated. Reboul (77, 78) claimed formation of a simple glycidyl quaternary chloride such as N-(2,3-epoxypropyl)trimethylammonium chloride (I). Later, Schmidt and Hartmann (22) reported formation of diquaternary salts, 2-hydroxytrimethylene-1,3-bis(trimethylammonium chloride) chlo(11) or 2-hydroxytrimethylene-l,3-bis(triethylammonium ride (111) and the presence of I-chloro-2-hydroxypropyltrialkylammonium chloride as a by-product. A patent (4) also claims preparation of simple glycidyl quaternary chlorides, More recently, Burness ( 2 ) reported that in acetonitrile, trimethylamine and epichlorohydrin form N-(3-hydroxy-lpropeny1)trimethylammonium chloride (IV) rather than the expected I. However, I has been synthesized by undisclosed methods and has been available for several years in research quantities ( 2 4 ) . Most recent information on the reaction comes from the Noguchi patent (74),which reports on the formation of N-(3-chloro-2-hydroxypropyl)trimethylammonium chloride (V) in almost theoretical yield when epichlorohydrin reacts with trimethylamine hydrochloride rather than with the free amine. While the latter method has been successful in the authors’ hands with the compounds men-
tioned, application of the reaction to triethylamine hydrochloride (VI) or to dimethyloctadecylamine hydrochloride has been unsuccessful. A linear diquaternary compound, 111, was obtained by use of V I as indicated in the experimental, and the quaternary obtained with the dimethyloctadecylamine hydrochloride contained no glycidyl group. The isolation of simple glycidyl quaternaries was doubted, since others (8, 20) had shown that aqueous secondary amines such as diethylamine or morpholine react with epichlorohydrin to form a tertiary amine which is also a chlorohydrin. The net result was reported to be a formation of substituted p dioxane derivatives. A similar observation was made by the writers (7 I ) with diethanolamine and epichlorohydrin in nonaqueous media. Ross, Baker, and Coscia (79) disagreed with this explanation of reactions with secondary amines and showed in one case, at least, that an azetedinium compound could be isolated. The effectiveness of chloride ions of amine salts as catalysts for epoxide ring openings has been known for some time (27, 28). Consideration of a third type of reaction based on epichlorohydrin as an alkyl halide should take into account the findings of Semb and McElvain (23) and Noller and Dinsmore (75). They demonstrated that a tertiary amine not only forms a quaternary salt by reaction with a primary halide, but also a hydrohalide of the amine and an unsaturated compound as well. Lohmann (9) and McKelvey, Webre, and Benerito (77) noted the complexity of the reaction between triethanolamine and epichlorohydrin in the absence of solvents at 25’ C., but nothing has been reported on this reaction. The use of a 3 to 1 molar ratio of epichlorohydrin to tertiary amine was suggested VOL. 6 NO. 2
JUNE 1 9 6 7
115
by the authors' interest in the nature of Ecteola-cellulose (70), an anion exchanger first introduced by Peterson and Sober (76) who prepared the exchanger from alkali-cellulose and a 3 to 1 molar ratio of epichlorohydrin and triethanolamine.
AMINEtEPOXIDE
0
9
0
= CHLORIDE
8
Experimental
Changes of Functional Groups with Time of Reaction. I n Figure 1 are illustrated the variations of chloride ion concentration as determined by a modified Volhard method and Durbetaki (3) titration data with time of reaction for an equimolar mixture of epichlorohydrin and triethanolamine at 25' C. The Durbetaki titration gives a measure of tertiary amine plus epoxide function expressed as milliequivalents per gram of mixture. The Durbetaki values fall slowly, and only after an induction period does the chloride ion concentration increase. A semilogarithmic plot of the Durbetaki values us. time is linear, but a similar plot for chloride ion is nonlinear. Concentrations of terminal epoxide rings of epichlorohydrin were also followed by measuring changes in absorptivity of the characteristic 2.2-micron band in the near-infrared region (6). The changes in absorptivity with time are illustrated in Figure 2 for the same reactants. The Durbetaki values fall slowly, showing only a 12% decrease during the first hour. There is a greater decrease in the terminal epoxide group as followed by changes in absorptivity at 2.2 microns. By the latter method, 5770 of the terminal epoxide groups had disappeared during the first hour. Shortly after that time interval, the mixture was no longer completely soluble in chloroform, the solvent used for the near-infrared analyses. These data suggest that in the absence of solvent the tertiary amine is first complexed at the oxirane ring of the epichlorohydrin. Only after the formation of this complex does a rearrangement resulting in release of ionic chloride occur. FYith an equimolar ratio of reactants a t 25' C., the ionic chloride content rises to a value consistent with that of triethanol-2,3-epoxypropylammoniumchloride after only 1 week, during which time the epoxide plus tertiary amine functions fall to zero, thus indicating the formation of [2,5-pdioxanylenebismethylene]bis[tris(2 - hydroxyethy1)ammonium chloride] (VII). Detection of Quaternary Compounds. Advantage was taken of a previously published method (25) for distinguishing qualitatively among primary, secondary, and tertiary amines. The method is based on colors produced by the amine and epichlorohydrin in the presence of chloranil. More recently, Sass et al. (27) reported that the original method did not allow for the identification of tertiary amines in the presence of tertiary amine salts when epichlorohydrin was the solvent, as both gave the same characteristic absorption bands. They suggested the use of solvents such as toluene. Others (73, 26) have recently published on the nature of similar molecular complexes. We have used a modification of the method (27) for a comparison of absorption spectra produced by compounds I11 and VI1 in the presence of chloranil in either toluene or epichlorohydrin with corresponding spectra of known amines, amine salts, and quaternary salts in the same media. Solutions of 1% by weight of Eastman research quality tetrachloroquinone, chloranil, in epichlorohydrin or in toluene served as stock solutions A. Stock solutions B were prepared by adding 2.5 micromoles of the various amines or amine salts to either 1 ml. of epichlorohydrin or 1 ml. of toluene. I n a typical experiment, 3 ml. of solution A was mixed with 1 ml. of solution B. The absorption of the mixture was measured a t 10-mg intervals by means of a Beckman DU spectrophotom116
I & E C PRODUCT RESEARCH A N D DEVELOPMENT
b
6 (3
\
0 W
I
4
2
0 I
2
3 4 TIME ( D A Y S )
5
6
Figure 1. Variation of ionic chlorine, 0, and Durbetaki value, 0, with time of reaction at 25 C .' of an equimolar mixture of triethanolamine and epichlorohydrin
AMINE
t
EPOXIDE
6
I
0
15
30
45
60
75
90
TIME (MINUTES)
Figure 2. Variation of terminal epoxide groups as determined by absorptivities at 2.2 microns in the near-infrared region with time of reaction of an equimolar mixture of triethanolamine and epichlorohydrin
eter in the 320- to 700-mp region. All measurements were made against the 1% chloranil solution in solvent as standard. The scanning was performed immediately after mixing and repeated at regular intervals. Changes in absorptivities with time for initial characteristic absorption peaks were noted as well as appearance and changes of peaks occurring after timed intervals. The amines or ammonium salts used in this study in addition to I11 and VI1 were mono-, di-, and triethylamines; mono-, di-, and triethanolamines; mono-, di-, and tripropylamines; tetrapropylammonium chloride; a sample of I furnished by Shell; cyclohexylamine; S,N'-dimethylcyclohexylamine ; A'cyclohexylpiperadine; and bis(N,N'-diethy1)piperazinium dichloride. Spectral data showed that the initial reaction between either tertiary amine used in this study and epichlorohydrin is the formation of a quaternary compound. I n the absence of epichlorohydrin, tertiary amines and chloranil in such solvents as toluene had characteristic absorption spectra a t 350 mp. I n the presence of epichlorohydrin, a sharp absorption band appeared immediately at 450 mp as well as the 350-mp band. The 450-mp band was not present when primary or secondary amines were substituted for the tertiary amine. T h e characteristic quaternary band at 450 mp was sharp and strong for the triethylamine, weak for the triethanolamine, and present for both compounds I11 and VI1 as well as in a known sample of I. Syntheses of 2-Hydroxytrimethylene-1,3-bis(triethylammonium Chloride) (111) from Triethylamine and Epichlorohydrin. When 9.25 grams (0.10 mole) of Fisher reagent grade epichlorohydrin (b.p. 114-16') and 10.12 grams (0.10 mole) of Eastman research grade triethylamine, which had been redistilled and dried, were mixed and allowed to remain a t room temperature for a few weeks, a brown, viscous oil separated from the homogeneous mixture. No exotherm was noted on mixing a t 25' C. The epichlorohydrin was consumed first, as the colorless top layer was practically pure triethylamine. At reflux temperature, the oil separated within 1 day. I n solvents such as dioxane or petroleum ether (0.1 mole of each reagent in 100 ml.), only approximately 10 grams of the oil separated in 4 to 5 months. The alkaline supernatant solvents were decanted and the oils washed to neutrality with fresh solvent. The brown products were dried at 85' to 90' C. and subjected to high vacuum pumping. The thick, viscous, noncrystalline products were mixtures only partially soluble in chloroform and only occasionally partially crystallized in the oven. Elemental analyses of these solids were not in agreement with those of a linear or cyclic diquaternary. IVhen the reagents were mixed in a 3 to 1 mole ratio, 277.5 grams (3.0 moles) of epichlorohydrin and 101.2 grams (1.0 mole) of triethylamine, at room temperature, there was no noticeable exotherm, but turbidity developed in a short time and a brownish oil began to separate. Separation continued for several weeks until approximately 7570 of the volume was in the lower brownish layer. When shaken, the top layer went into homogeneous solution. Viscosity of the mixture increased with time, and after 6 weeks crystallization began. O n only one occasion did crystallization occur as early as after 4 weeks. Results were slightly better when especially dried reagents were allowed to react in tightly stoppered flasks. The yield was 11.3 grams of crystalline 111. Recrystallization from dimethylformamide yielded white, granular, very hygroscopic crystals (m.p. 245-48' C. with decomposition). Heating of the mother liquor for 3 hours a t 75' and then cooling to room temperature produced an additional 73.8 grams of 111. Yields based on triethylamine varied from 53.8 to 56%.
Infrared analyses of product showed no bands characteristic of a substituted p-dioxane ( 5 ) . ANALYSIS.Calculated for C & ~ ~ C ~ Z N(111) Z O : total C1, 21.4; ionic C1, 21.4; N, 8.4. Found: total C1, 21.3; ionic C1, 21.4; N, 8.5. KO more crystalline material could be obtained from the thick, tarry mother liquor, which was still rich in ionic chloride, even when it was cooled to dry ice temperature. Approximately 1 mole of epichlorohydrin could be distilled from the liquor along with small amounts of a neutral, water-insoluble, nitrogen-free liquid (b.p. >120-25' C.). Fractional distillation under 1- to 2-mm. pressure of the latter fraction yielded only a few milliliters of the liquid and a tar possessing an aromatic odor. I t is believed that the liquid, as judged from classification and elemental analyses, was a mixture of epichlorohydrin and probably chloropropionaldehyde. I t is possible that the latter resulted from thermal degradation of the tar. [2,5-/~-Dioxanylenebismethylene Ibis [tris(2-hydroxyethy1)ammonium Chloride] (VII). When 9.25 grams (0.10 mole) of epichlorohydrin and 14.92 (0.10 mole) of Union Carbide Chemical Co. research grade triethanolamine were well mixed at 25' C. in closed flasks, there was a slight exotherm. Maximum temperature reached 35' to 40' C. within the first 5 to 10 minutes. After 2 weeks, a viscous, yellowish, noncrystalline, water-soluble wax was formed. The wax was insoluble in absolute ethanol or glacial acetic acid. The mixture was soluble at all times in methanol. The ionic chloride content of the mixture standing at 25' C. reached 14.6y0, the theoretical amount required for the simple glycidyl quaternary chloride after a few weeks. During this interval, however, the total amount of tertiary nitrogen and epoxide groups, as determined by the Durbetaki method (3)of hydrogen bromide consumption, approached zero. The product did not add bromine or iodine by the Wijs method, but did reduce Baeyer's reagent. The latter test for unsaturation is not valid here, however, as both triethanolamine and its hydrochloride reduce neutral permanganate solutions rapidly. Infrared analyses showed the presence of absorption bands in the 8.8to 9.4-micron region characteristic of a p-dioxane ( 5 ) . IVhen 10 grams of a reaction mixture, which had remained 2.5 days at 25' C., was dissolved in 50 ml. of glacial acetic acid, 2.45 grams of granular triethanolamine hydrochloride (VIII) was obtained and recrystallized from hot ethanol. ANALYSIS.Calculated for C ~ H I ~ C ~(VIII) N O ~: total or ionic C1, 19.1; lit. m.p. 177'. Found: ionic C1, 19.2; total C1, 19.2; m.p. 178'. The dissolution of another 10 grams of the above mixture in ethanol indicated that VI11 was not present as such in the mixture. After 3.5 days the reaction mixture was no longer completely soluble in ethanol, and a waxy precipitate (VII) was formed. The amounts of VI11 precipitated from the glacial acetic acid varied from 11 weight yoafter 1 day to 26% after 2 days, 15.5% after 3.5 days, and 0% after 7.5 days. Thus, after 7.5 days, a negligible amount of the free amine remained in the reaction mixture. Only after the addition of a drop of triethanolamine to the clear solution of VI1 in the glacial acetic acid-methanol (20 to I), was some VI11 precipitated as in the earlier stages. The reaction was too vigorous to be carried out at higher temperatures. Heating of the reaction mixture on a water bath a t 80' to 85' C. for a few minutes caused violent boiling and formation of a black, thick paste which was largely insoluble in ethanol or glacial acetic acid. However, from the latter solvent, a small amount of VI11 was precipitated. VOL. 6
NO. 2
JUNE 1 9 6 7
117
Equimolar quantities (0.2 mole) of epichlorohydrin and triethanolamine were added to 100 ml. of various solvents and allowed to react at 25' C. for several months. After 2 months, nothing precipitated from the methanolic solution. Only 2 grams of a wax was obtained after 1.5 months when the solvent was ethanol, dioxane, or chloroform. Approximately 7 grams of VI1 precipitated from the 1-butanol solution after only 20 days. The most efficient way found to obtain VI1 was by refluxing the chloroform solution for approximately 6 hours, after which time 35 grams (7201, yield) of a slightly yellow material floated to the surface. Slightly better yields, but of a darker product, were obtained from heated 1-butanol. I n glacial acetic acid, no precipitate appeared in a month, but after the aged solution had been boiled for 4 hours a few needles of VI11 appeared after a few days at 25' C. When excess epichlorohydrin was the solvent (3 to 1 mole ratio), a practically quantitative precipitation of VI1 occurred after 3 weeks at 25' C. Two thirds of the epichlorohydrin was recovered. Attempts to crystallize VI1 from mixed solvents, such as methanol-ethanol-dimethylformamide, were unsuccessful. A crystalline solid, precipitated from a methanolic solution at the temperature of dry ice, formed a viscous methanolic solution at 25' C. The white, slightly alkaline wax obtained from the 1-butanol reaction mixture a t 25' C. was washed in hot 1-butanol, and then boiled in successive portions of absolute ethanol. After high-vacuum drying at 75' C. for 2 days, a slightly yellow, glassy solid remained (softening point 65' to 70' C.). This solid was soluble in methanol, water (pH 7), and glacial acetic acid to which a little methanol (20 to 1) had been added. ANALYSIS.Calculated for ClsH4&l2N20s(VII) : total C1, 14.69; ionic C1, 14.69; N, 5.8; milliequivalentsof oxirane 0 plus tertiary N, 0.0. Found: total C1, 14.2; ionic C1, 14.4; N, 5.9; milliequivalents of oxirane 0 plus tertiary N, 0.01. When 10 grams of VI1 obtained above was made to react with 50 ml. of acetic anhydride containing 2 ml. of concentrated hydrochloric acid on a steam bath for 3 hours, no precipitation occurred even after evaporation at reduced pressures. The glassy product obtained on acetylation dissolved in chloroform. After reprecipitation several times with dry ether to remove the acetic anhydride, the sample was dried in vacuo to a glassy solid. ANALYSIS.Calculated for completely acetylated VI1 : acetyl, 33.89. Found: acetyl, 34.30. When the clear methanolic reaction mixture which had been aged for 2 months at room temperature was stripped of methanol in a rotary evaporator at 25' C., the residue was a colorless, alkaline, viscous liquid of approximately 10% ionic chloride. The residue was about 25y0 insoluble in glacial acetic acid, and recrystallization of the white powder from hot ethanol yielded needles of VIII. When another portion of the clear sirup was added to boiling ethanol, only partial solubility resulted, and a white, waxy precipitate of VI1 remained. No VI11 precipitated on cooling the alcoholic filtrate, indicating that glacial acetic acid had reacted with a portion of the original sirup to form V I I I . A clear solution was formed when VI1 was dissolved in a 20 to 1 mixture of glacial acetic acid and methanol, but addition of a drop of triethanolamine caused a precipitate of V I I I . Investigation of Noguchi-Sakota Reaction. N-(3-chloro2-hydroxypropyl)trimethylammonium chloride (V) was prepared with results as reported previously (74)by reaction of equimolar quantities of the trimethylamine hydrochloride and
118
l&EC PRODUCT RESEARCH A N D DEVELOPMENT
epichlorohydrin. The reaction is vigorous in ethanol with liberation of heat and loss of trimethylamine if the temperature rises as high as 35' C. O n one occasion 0.15 mole of 1,3dichloropropanol was recovered from the reaction mixture. The white, crystalline product (V) was recrystallized from hot ethanol. ANALYSIS.Calculated for V : total C1, 37.76; ionic C1, 18.88; N, 7.45; lit. map. 190." Found: Total C1, 37.58; ionic C1, 18.74; N, 7.47; m.p. 190'. Substitution of triethylamine hydrochloride (VI) for the trimethylamine hydrochloride resulted in a sluggish reaction. When 68.86 grams (0.50 mole) of triethylamine hydrochloride and 46.25 grams (0.50 mole) of epichlorohydrin were dissolved in 150 ml. of absolute ethanol and heated for several hours at 65' to 70' C., a homogeneous solution resulted. After the solvent and excess amine were stripped off,a soft, brown mass which formed a glass on freezing resulted. Many attempts to obtain crystals were unsuccessful. When 20 grams of the product were dissolved in water and ether-extracted three times, 5.5 grams of 1,3-dichloropropanol was recovered. Finally, the balsam remaining after solution, extraction, and evaporation of water yielded with dimethylformamide very hygroscopic crystals of 111. When 10.12 grams (0.1 mole) of triethylamine and 12.91 grams (0.10 mole) of 1,3-dichloropropanol were refluxed for 11 hours in 25 ml. of absolute ethanol, a soft wax similar to the above was obtained after the solvent was stripped. After dissolving in water and ether extraction, only 2 grams of 1,3dichloropropanol was obtained. Crystallization of the residue from dimethylformamide yielded 111. All attempts to isolate N - (3-chloro-2-hydroxypropyl) trimethylammonium chloride were unsuccessful. Attempts to make dimethyloctadecylamine or its hydrochloride react with epichlorohydrin to form a glycidyl quaternary compound were also unsuccessful. Quaternary compounds were formed, but they did not contain epoxide groups or their chlorohydrin precursor groups. Discussion
In this study, compound I11 has been isolated as white, extremely hygroscopic crystals after a 2-month reaction a t 25' C. There remains, however, the explanation of the addition of the second mole of tertiary amine to the simple glycidyl quaternary salt. Since the reaction occurs in nonaqueous media, a probable mechanism is the extraction of hydrogen chloride from the epichlorohydrin by the tertiary amine. If the mechanism of epichlorohydrin reacting as an alkyl halide is correct, some triethylamine hydrochloride should be formed. As a result, some rearrangement of epichlorohydrin to acrolein or allyl alcohol should occur, or the rearrangement might occur after the formation of the quaternary with formation of a triethylpropenylammonium chloride similar to IV. In either event, the hydrochloric acid formed would furnish the proton or add to epichlorohydrin to form 1,3-dichloropropanol. A number of equilibria are involved, the sequence of which is not fully understood. O n the other hand, triethanolamine forms [2,5-p-dioxanylenebismethylene Ibis [ tris (2-hydroxyethyl) ammonium chloride] (VII), which has been isolated in this investigation as a white, solvated, waxy solid. Triethanolamine hydrochloride (VIII) has also been isolated from the reaction mixture only during the initial stages of reaction and only after the addition of glacial acetic acid. The formation of VI11 is believed to be by an anion exchange between the acetate of the unreacted amine
and the chloride ion of the glycidyl quaternary present as an intermediate. Such anion exchanges are known (7). Since with equimolar quantities of epichlorohydrin and triethylamine, the former is consumed first, a molecule of triethylamine must extract a molecule of hydrogen chloride from one molecule of epichlorohydrin. T h e resultant triethylamine hydrochloride then reacts with a second molecule of epichlorohydrin. Triethylamine can be alkylated only once by epichlorohydrin. However, it might be argued that the alkylation product reacts further with epichlorohydrin. Several such modes of reaction can be envisaged, but the fact that an excess of epichlorohydrin leads to a product which involves 2 moles of triethylamine and 1 of epichlorohydrin strongly negates such possibilities. The isolation of the 2 to 1 product from a reaction mixture which contains an excess of epichlorohydrin also explains the failure of the Noguchi-Sakota reaction with triethylamine. Experimental evidence shows clearly that the second mole of triethylamine adds faster than the first. Therefore, because of the nature of the products isolated and consideration of the spectroscopic data obtained on reaction mixtures, the mechanism proposed for the formation of the linear diquaternary 111, where R = C Z H ~is, as follows:
RBN: n 4- CH,-CHCH,CI
+
+ E
R,NCH, HCH,Cl
Also, there is a possibility of the following reactions, since I11 can be isolated by reaction of triethylamine with 1,3dichloropropanol.
0
/\
CHz-CHCHzC1
+VI
+
ClCHzCHOHCHiCl
+ 2R3N:
ClCHzCHOHCHzCl
-+
+ R3N:
I11
(6)
(7)
The first step of the mechanism proposed for the formation of the cyclic diquaternary (VII) is the same as Equation 1, except that R = C2H40H. In spite of the weaker basicity of this base (pKB = 6.2 compared to pKB = 3.3 for the triethylamine), the reaction is more exothermic. The mild exotherm at room temperature and violent reaction at higher temperatures are indicative of rapid epoxide-opening reactions. The greater rate of reaction with triethanolamine, as compared with triethylamine, may result from the higher polarity of the reaction medium and steric effects favoring formation of the dioxane ring which overcomes the deficiency in nucleophilicity of the triethanolamine. With this amine only the following occurs:
+
Only after addition of glacial acetic acid to the mixture can the triethanolamine hydrochloride (VIII) be precipitated as shown:
0 +
0
RaNH CHsCOG
/ \
+
/\
+ R3NCHzCH-CHz
Ci
-+
0
+ R ~ N C H ~/C H\- C H ZC H I C O D +
VI11 literature Cited
/”\
&N: -I- CH,-CHCH,CI
7 R,NH El
+
+
unsaturate (3)
VI
VI
(9)
+ (A) + R3NCHzCHOHCHzNRa + +
2 ‘Zi
(4)
I11
(B)
+ HCl
-+
(1) Bradley, W., Forrest, J., Stephenson, O., J . Chem. Soc. 1951, p. 2877. (2) Burness, D. M., J . Org. Chem. 29,1862 (1964). (3) Durbetaki, A. J., Anal. Chem. 28, 2000 (1956). (4) E. I. du Pont de Nemours & Co., Inc., Brit. Patent 477,981 (March 29, 1935). (5) Fratiello, A., Luongo, J. P., J . A m . Chem. Soc. 85, 3072 (1963). (6) Goddu, R. F., Delker, D. A., Anal. Chem. 30, 2013 (1958). (7) Goerdeler, J., in “Methoden der Organische Chemie,” Vol. VI. 4th ed.. Houben-Wevl. ed.. DD. 621-2. GeorF Thieme Verlag, Stuttgart, Germany,‘ 1958. (8) Heywood, D. L., Phillips, B., J . A m . Chem. SOG.80, 1257 (1958). (9) Lohmann, H., J . Prakt. Chem. 153, 57 (1939). (10) McKelvey, J. B., Benerito, R. R., manuscript in review. (11) McKelvey, J. B., Webre, B. G., Benerito, R. R., J . o ~ g . Chem. 25, 1424 (1960). (12) McKelvey, J. B., Webre, B. G., Klein, E., Ibid., 24, 614 (1959). (13) Mukherjee, D. C., Chandra, A. K., J . Phys. Chem. 68, 477 (1964). (14) Noguchi, J., Sakota, N., U.S. Patent 3,135,788 (June 2, 1964). (15) Noller, C. R., Dinsmore, R., J . Am. Chem. Sod. 53, 1185 (1931); 54, 1025 (1932). (16) Peterson, E. A,, Sober, H . A., Ibid., 78, 751 (1956). (17) Reboul, E., Compt. Rend. 93, 421 (1881). (18) Ibid., 97, 1556 (1883). (19) Ross, J. H., Baker, D., Coscia, A. T., J . Org. Chem. 29, 824 (1964). (20) Rothstein, R., Binovic, K., Delor, I., Compt. Rend. 236, 1050 11953). (21) Sa&, S., Kaufman, J., Cardenas, A , , Martin, J. J., Anal. Chem. 30, 529 (1958). (22) Schmidt, E. A,, Hartmann, H., Ann. 337,116 (1904). ,
I11
(5)
Formation of I11 depends upon the extraction of HC1 from epichlorohydrin or its equivalent (7, 2, 72). Since a greater than 50% yield of I11 based on the triethylamine can be isolated, it is less likely that the needed mole of HCl is extracted by the removal of a proton from the electron-deficient methylene adjacent to the nitrogen in the initially formed quaternary, A . Also, the lack of an initial exothermic reaction between epichlorohydrin and triethylamine is suggestive of a slow extraction of HC1 from epichlorohydrin, such as indicated in Equation 3, rather than a rapid epoxide opening reaction. Epichlorohydrin would be expected to rearrange (29), as in the propenol quaternary isolated by Burness (2). However, no unsaturate or rearranged derivative of epichlorohydrin could be isolated.
VOL. 6
A
I
NO. 2
Y
JUNE 1 9 6 7
119
(23) Semb, J., McElvain, S. M., J . Am. Chem. SOC. 53, 690 (1931). (24) Shell Chemical Co., New York, N. Y., “Glycidyltrimethylammonium Chloride,” Tech. Lit. PD-140(November 1962). Chim. 2, 623 (1935). (25) Sividjian, J., Bull. SOC. (26) Sloneker, J. V., Mooberry, J. B., Schmidt, P. R., Pittsley, J. E., Watson, P. R., Jeanes, A., Anal. Chem. 37, 243 (1965). (27) Speranza, G. P., Peppel, W. J., J . Org. Chem. 23, 1922 (1958). (28) Strukov, I. T., Khim. Farm. Prom. 2, 11 (1934); Chem. Abstr. 28, 5421 (1934).
(29) Winstein, S., Henderson, R. B., in “Heterocyclic Compounds,’’ Vol. I, R. C. Elderfield, ed., p. 47, Wiley, New York, 1950. RECEIVED for review June 20, 1966 ACCEPTEDMarch 20, 1967 Presented in part before the Section of Organic Chemistry at the Sixteenth Annual Southeastern Regional Meeting of the American Chemical Society in Charleston, W. Va., October 1964. One of the laboratories of the Southern Utilization Research and Development Division, Agricultural Research Service, US.Department of Agriculture.
BRASSYLIC ACID FROM OZONOLYSIS OF ERUCIC ACID H . J. N I E S C H L A G A N D I . A. W O L F F Northern Regional Research Laboratory, U S . Department of Agriculture, Peoria, Ill. 61604
T. C. M A N L E Y A N D
R. J . H O L L A N D
The Welsbach Corp., Philadelphia, Pa. 19129
In bench-scale experiments, brassylic acid of 98y0 purity was isolated in 70% of theoretical yield by ozonolysis of erucic acid. Alternatively, dimethyl brassylate of 95% purity was obtained in 88% yield. Brassylic acid of 95% purity was produced in a continuous 7-day pilot-plant process, but the achievable yield demonstrated in the laboratory was not realized in this preliminary scale-up,
HE use of ozone to effect oxidative cleavage of an unsatuTrated fatty acid is exemplified by the commercial production of pelargonic and azelaic acids from oleic acid (3, 8). Ozonolysis of erucic (cis-1 3-docosenoic) acid yields the same monobasic acid, pelargonic, but a different dibasic acid, brassylic or tridecanedioic acid. Brassylic acid is a longer straight-chain aliphatic dicarboxylic acid than hitherto readily obtainable in quantity. Availability of brassylic acid would extend the range of properties in derivatives of such aliphatic dibasic acids. We have shown that selected esters of brassylic acid are excellent low-temperature plasticizers for poly(viny1 chloride) with exceptional light stability (73, 74). Esters of brassylic acid are also reported to be suitable as lubricants over a wide range of temperature(6) ; the macrocyclic ester, ethylene brassylate, has been prepared for use as a synthetic musk (76). Another intriguing possibility under study is the production of new nylons from brassylic acid (4). A new oilseed crop, Crambe abyssinica, usually referred to as crambe, is a rich source of erucic acid, containing 55 to 6OY0 of the acid as glyceride ester in the seed oil (75). The U.S. Department of Agriculture has been encouraging and sponsoring the development of crambe as a new industrial crop for several years, with the result that beginning in 1965, substantial quantities of crambe oil became available commercially ( 5 ) . An important aspect of expanding the industrial utilization of crambe oil may be the efficient production of brassylic acid from erucic acid. I n this paper we report results on the continuous ozonolysis of erucic acid on a pilot-plant scale under one set of operating conditions. Bench-scale studies aimed at defining preferred conditions for carrying out the ozonolysis are also described.
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I & E C PRODUCT RESEARCH A N D DEVELOPMENT
Experimental
Bench-Scale Ozonolysis. OZONIZATION. Ozonization of erucic acid (5 to 20 grams) in solution was carried out in an Ace Mini-lab batch reactor with oxygen containing 2 to 3y0 ozone at a flow rate of 300 ml. per minute. The ozone concentration was determined by the standard thiosulfate titration of iodine liberated from potassium iodide (10). Ozonization was continued to an end point determined by the appearance of color in an acidified potassium iodide solution through which the exit gases were passed. The ozone-oxygen mixture was introduced into the reaction medium through a glass sparger. Adequate mixing was effected by the gas flow; for the two-phase systems, mixing was augmented by magnetic stirring. OXIDATION OF INTERMEDIATES. Following ozonization, the intermediate products were oxidized by one of two procedures: PEROXIDE.Fifty milliliters BY ADDITIONOF HYDROGEN of acetic acid containing 10 mole equivalents of hydrogen peroxide (30%) per mole of erucic acid was added sloivly, with stirring, to the reaction mixture. The mixture was gradually warmed on a steam bath and then kept hot for l’/~ to 2 hours. Excess peroxides were destroyed by adding sodium bisulfite until potassium iodide-starch paper gave a negative test. WITH OXYGEN.The ozonized reaction mixture was added slowly dropwise at the top of a vertically positioned, steamheated, spiral glass condenser so that it flowed downward by gravity through the coiled tubing and into a 250-ml. roundbottomed collection flask, heated on a steam bath. A countercurrent flow of oxygen (300 ml. per minute) \vas introduced through a sparger into the bottom collection flask so that the gas passed through the collected product and upward through the coiled tube. As oxidized product accumulated in the collection flask, it served to dilute the incoming partially oxidized material. The temperature in the collection flask was maintained at slightly above 100’ C. by controlling the rate of addition of solution at the top of the condenser. The reaction is exothermic at about 85-90’ C. as long as unoxidized
