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Ind. Eng. Chem. Res. 2002, 41, 2602-2610
Ammonolysis of Allyl Chloride by Ammonia Solution Waldemar Paz´ dzioch* and Eugeniusz Milchert Technical University of Szczecin, Institute of Organic Chemical Technology, Pulaskiego 10, PL 70-322 Szczecin, Poland
The preparation of allylamines by the ammonolysis of allyl chloride using ammonia in the presence Cu2Cl2 as a catalyst has been examined. The influence of essential reaction parameters on the selectivity of the transformation into monoallylamine, diallylamine, and triallylamine in relation to the allyl chloride consumed and on the conversion of allyl chloride has been described by regression equations in the form of a polynomial of the second-order. The optimum values of temperature, reaction time, molar ratio of NH3/allyl chloride, and molar ratio of Cu2Cl2/allyl chloride have been determined. Introduction Monoallylamine (MAA) is one of the major raw materials for the synthesis of (aminopropyl)triethoxysilane, a silane-bonding agent used for the production of glass fibers, for the modification of organic polymer properties, and for mineral fillers.1 Monoallylamine also finds applications in the manufacture of insecticides, retardants,1 cross-linking agents, thickening agents for dyes, water-thinnable paints, and hardeners for epoxy resins.1,2 It is also used for the preparation of tranquilizers,3 anti-inflammatories,4 diuretics,5 and cytostatics.6 MAA finds applications in the production of ionexchange resins,7 aminoalkyl polymers,8,9 photosetting10 and thermostable11 resins, hardening accelerators for resol-type phenolic resins,12 epoxy-based adhesives,13 organophilic fillers of rubber compounds,14 adhesives for lamination,15 oil additives,16 and foam inhibitors.17 The incorporation of MAA into the polyacrylonitrile18 or certain wool blends improves the dyeability of those materials.19,20 From acrylic copolymers modified by MAA can be formed strong fibers, which are resistant to hot water,21 with a characteristic silk-like feel.22 MAA is also useful in textile printing,23,24 in solvents for printing inks,25 and in dyeing.26 Derivatives of phenoxyphosphoric acid and MAA27 are used as bactericides and fungicides. The reaction of aryl and heteroaryl halides with MAA or diallylamine in the presence of palladium catalyst leads to the formation of aniline and aryloaniline.28 MAA is used in the syntheses of several inhibitors such as 2,3-dihydro-1,4benzoxanthiins,29 benzodioxynecarboxyamides,30 and carboxyamides of dihydrobenzofuran.31 MAA also promotes tire cord adhesion,32 and acrylamide/allylamide copolymers strengthen paper.33,34 There is lack of information in the literature concerning the technological conditions of allylamine synthesis. In this work, the influence of technological parameters on the synthesis of allylamines was studied, and the optimum conditions of the synthesis were determined. Experimental Procedures Materials. The following materials were used in the process: aqueous ammonia, 25 wt %, obtained from * Corresponding author. Fax: +48 91 449 43 65. E-mail:
[email protected].
Polish Chemical Reagents (PCR, Gliwice, Poland); copper (I) chloride from Aldrich (St. Louis, MO); and allyl chloride (AC) from Chemical Plant “Organika-Zachem” in Bydgoszcz (Poland). AC was distilled prior to use. The purity of allyl chloride applied in the experiments was -99.9% (GC method). Apparatus. The ammonolysis of AC was carried out in a glass apparatus, shown in Figure 1. The apparatus comprises a reactor (1) of 6 dm3 capacity which was placed in a water bath (2) with the possibility of cooling or heating. The reactor was equipped with a high-rotary stirrer (3), thermometer (4), and reflux condenser (5) cooled by water. A propeller agitator with speed of rotation of 800 rpm was used. As a method of condensing the vapors, under the reflux condenser (11) was located the product receiver (6). Allyl chloride was introduced under the surface of liquid in the reactor. Allyl chloride was supplied by a metering pump (7) from a container (8). On a stage of separation for the ammonolysis product, a solution of sodium hydroxide was introduced from container (8) to the reactor (1), utilizing the same method. The major amount of allylamines was condensed in a reflux condenser (11) which was cooled by freezing the mixture at a temperature of -30 °C. A condensate was accumulated in the receivers (12). The allylamines drained of from the reflux condenser (5) were cooled in condenser (10) and collected in product receivers (6) and (12). After the condensation of allylamines, the gas mainly contained ammonia. Ammonia was absorbed in water in a scrubber (13). Absorbate from the receiver (14) was recirculated to the scrubber using a peristaltic pump (15). Nonabsorbed ammonia was directed toward the scrubber (16) sprinkled with a 2% sulfuric acid solution. A solution of sulfate and ammonia in sulfuric acid was collected in the receiver (17). Methods of Measurement. A catalyst (cuprous (I) chloride) and a 25% solution of aqueous ammonia was introduced into the reactor. The content was mixed vigorously, with the process temperature established. Allyl chloride was introduced at a constant rate of 300 g/h. After completing the introduction, the content of the reactor was mixed for 1 h. During the synthesis, the systems for amine collection, NH3 absorption, and tail gas destruction were operated in continuous mode. Subsequently, a 40% sodium hydroxide solution was introduced into the reactor. Amine hydrochlorides were
10.1021/ie010564r CCC: $22.00 © 2002 American Chemical Society Published on Web 04/26/2002
Ind. Eng. Chem. Res., Vol. 41, No. 11, 2002 2603
Figure 1. Scheme of apparatus for synthesis of allylamines: (1) reactor, (2) water bath, (3) mixer, (4) thermometer, (5, 11) reflux condenser, (6) product receiver, (7, 15) peristaltic pump, (8) container for allyl chloride, (9) container for sodium hydroxide solution, (10) condenser, (12, 17) receiver, (13) packet scrubber, (14) aqueous ammonia receiver, (16) scrubber, (18) container for 2% H2SO4.
transformed into free amines, which formed a separate phase. After the reaction mixture was cooled to room temperature, the stirrer was stopped. A separated organic layer was subjected to distillation. The condensation system behind the reactor was utilized for the distillation. The distillation was terminated after the pot temperature reached 75 °C. Ammonia was absorbed with 2 wt % sulfuric acid solution in the system for the destruction of tail gases. The concentrations of allylamine and unreacted allyl chloride in the distillates, absorbates of ammonia, and in the product after the treatment with sodium hydroxide solution were determined by a GC method. As a result of fractional distillation, the allylamines were obtained with the following purity (wt %): MAA, 99.2; diallylamine (DAA), 99.1; triallylamine (TAA), 99.9. After the mass balance for each experiment was performed, the allyl chloride conversion, the selectivities of transformation to MAA (y1), DAA (y2), and TAA (y3) were calculated. The selectivity was calculated in relation to the allyl chloride consumed. Analytical Methods. Concentrations of MAA, DAA, TAA, and AC were determined both in organic and water layers. Analyses were carried out by a GC/MS method on a Trace 2000 apparatus with a mass spectrometry detector (MS Voyager Finnigan). Organic compounds in the organic and aqueous layers were determined using a DB-5MS column (60 m length, 0.25 mm i.d., and 0.25 mm film thickness). The temperature of the column was changed gradually to 35 °C in 5 min, with an increase to 100 °C at the rate of 10 °C/min. The
split/splitless sample injector temperature was 200 °C (split 50:1). The detector source temperature was 250 °C, electron ionization at 70 eV. The carrier gas (He) flow rate was 1 cm3/min. A quantitative gas chromatography analysis was performed by an internal standard method using 1,4-dioxane as the internal standard. MAA, DAA, and TAA, used as standards, were isolated from ammonolysis product by column distillation. Their chemical composition was confirmed by an MS method. Results and Discussion Preliminary Investigations and Methods of Calculations. Preliminary investigations revealed that the ammonolysis of AC resulted in MAA, DAA, and TAA in proportions dependent on the process parameters. The course of the process depends on the temperature, reaction time, and the molar ratios of NH3/AC and of Cu2Cl2/AC. Reactions of the process can be presented by the following equations:
CH2dCHsCH2Cl + 2NH3 f CH2dCHsCH2NH2 + NH4Cl CH2dCHsCH2NH2 + CH2dCHsCH2Cl + NH3 f (CH2dCHsCH2)2NH + NH4Cl
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Ind. Eng. Chem. Res., Vol. 41, No. 11, 2002
(CH2dCHsCH2)2NH + CH2dCHsCH2Cl + NH3 f (CH2dCHsCH2)3N + NH4Cl Subsequently, the unreacted allyl chloride reacts with MAA, and this reaction is promoted by greater basicity of the amine in comparison to that of ammonia
CH2dCHsCH2Cl + CH2dCHsCH2NH2 f (CH2dCHsCH2)2NH‚HCl
Table 1. Levels of Examined Factors
level
coded factor
temp [°C] x1a
star lower lower basic higher star higher
-2 -1 0 1 2
5 15 25 35 45
a
The greater basicity of MAA, DAA, or TAA also implies that, in the reaction mixture, the amines exist partly in the form hydrochlorides. Thus, one can speak about equilibrium
CH2dCHsCH2NH2 + NH4Cl h CH2dCHsCH2NH2‚HCl + NH3 Such an equilibrium also forms the remaining allylamines. Allyl alcohol is a byproduct.
CH2dCHsCH2Cl + H2O f CH2dCHsCH2OH + HCl Thus, a part of the MAA is transformed into inactive hydrochloride, and it does not take part in the formation of DAA and TAA. The addition of ammonium chloride at the beginning of the reaction intensifies the formation of amine hydrochlorides and allows for a diminishing of the ammonia excess. The yield achieved was similar to that when a significantly greater excess of ammonia was applied. The influence of the reaction parameters (independent factors) on the course of the process was investigated applying the statistical methods of design of experiments. The experiments were performed according to rotatable uniform design.35,36 Changes to these parameters in natural and coded forms on the levels resulting from the design of experiments are presented in Table 1. The matrix of experiment design and the experimental values of the response functions y1-y4 are compiled in Table 2. Using the computer program STATISTICA PL, each of the response functions was represented by a regression equation (Y1-Y4) in the form of a polynomial of the second-order37 k
Yi ) b0 +
∑ i)1
k
bi x i +
∑ i< j
k
bi j xi xj +
bii xi2 ∑ i)1
where Yi ) the response function (the selectivity of the transformation to MAA, DAA, or TAA or allyl chloride conversion); b0, bi, bi j, bii ) the regression equations coefficients; xi, xj ) the independent factors (parameters); and k ) the number of independent factors in the experiment design (k ) 4). The insignificant coefficients were eliminated on the basis of the student’s t test. On the basis of the FisherSnedecor test, the adequacy of the equations at the significance level of R e 0.05 was proved as R(F) > a*.37 The coefficients of the regression equations in natural form and the results of the statistic analysis are shown in Table 3. The optimization of the regression equations was performed by the simplex method with a limitation on variables and the “branch-and-bound” method.38 For a comparison, the optimization was also performed nu-
NH3/AC molar ratio [mol‚mol-1] x2a
CuCl/AC molar ratio [mol‚mol-1] x3a
reaction time [h] x4a
1.00 3.25 5.50 7.75 10.00
0.010 0.035 0.060 0.085 0.110
1 2 3 4 5
x1, x2, x3, x4 ) independent factors.
merically applying the Gauss-Siedel and Hook-Jeeves methods.39 Each method gave similar values of optima. Optimum values of the response functions and corresponding values of the process parameters are given in Table 4. Influence of Parameters on Allyl Chloride Ammonolysis. The influence of parameters on AC conversion and the selectivity of transformation to MAA, DAA, and TAA in relation to AC consumed were investigated on the basis of the regression equations. The analyses were performed applying a two-dimensional section of the response surfaces. Sections represent the lines of the same values of the response functions (Y1-Y4) under investigation when the two parameters were changed. The values of the two-further parameters were then established on a level ensuring the maximum of the function. Influence of Parameters on the Selectivity of Transformation to MAA in Relation to Allyl Chloride Consumed (Y1). All independent variables significantly influence on the selectivity of the transformation to MAA in relation to consumed allyl chloride. The greatest effect is the temperature (Figures 2 and 3) and has the molar ratio of NH3/AC (Figures 4 and 5). The increase of temperature from 5 to 28 °C, when the remaining parameters have the most favorable values, results in an increase of the selectivity of the transformation to MAA from 43 to 71 mol %. The greatest increase of selectivity occurs for a lower range of temperatures. An increase of the temperature above 37 °C reduces the selectivity of the transformation to MAA. This selectivity declines to 66 mol % at a temperature of 45 °C. Over the temperature range of 2838 °C, the function demonstrates a region of a flattened maximum with a significant domain of variance, independent of the kind of cooperating factor. An increase in the molar ratio of NH3/AC from 1.0 to 6.5 mol‚mol-1 with the same remaining parameters of the process causes an increase in the selectivity of the transformation to MAA from 53 to 71 mol % (Figures 4 and 5). The greatest increase is observed in the lower range of investigated interval. Above the molar ratio of NH3/AC ) 9, a small decline in the selectivity of the transformation to MAA to 69 mol % takes place. A simultaneous influence of the temperature and NH3/ AC molar ratio is presented in Figure 6. These parameters have influence to a similar degree on the selectivity of the transformation to MAA. The influence of the CuCl/AC molar ratio on the selectivity of the transformation to MAA (Figures 4 and 7) is significantly smaller in comparison with the parameters discussed previously. An increase in a ratio from 0.01 to 0.05 mol‚mol-1, for the most beneficial values of the remaining parameters, causes a slight decline in the selectivity of the transformation to MAA. At the boundary of variability interval (i.e., at a CuCl/
Ind. Eng. Chem. Res., Vol. 41, No. 11, 2002 2605 Table 2. Design Matrix and Experimental Results no.
x1 [°C]
x2 [mol‚mol-1]
x3 [mol‚mol-1]
x4 [h]
y1 [mol %]
y2 [mol %]
y3 [mol %]
y4 [mol %]
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
15 35 15 35 15 35 15 35 15 35 15 35 15 35 15 35 45 5 25 25 25 25 25 25 25 25 25 25 25 25 25
3.25 3.25 7.75 7.75 3.25 3.25 7.75 7.75 3.25 3.25 7.75 7.75 3.25 3.25 7.75 7.75 5.50 5.50 10.00 1.00 5.50 5.50 5.50 5.50 5.50 5.50 5.50 5.50 5.50 5.50 5.50
0.035 0.035 0.035 0.035 0.085 0.085 0.085 0.085 0.035 0.035 0.035 0.035 0.085 0.085 0.085 0.085 0.060 0.060 0.060 0.060 0.110 0.010 0.060 0.060 0.060 0.060 0.060 0.060 0.060 0.060 0.060
2 2 2 2 2 2 2 2 4 4 4 4 4 4 4 4 3 3 3 3 3 3 5 1 3 3 3 3 3 3 3
40.3 62.2 51.8 70.0 50.0 63.5 60.6 72.2 41.4 63.5 52.8 71.9 50.8 65.2 62.6 73.4 67.8 35.9 68.7 47.7 68.4 57.5 67.4 63.4 66.8 65.9 67.3 67.5 65.8 66.9 68.6
44.3 28.8 35.1 21.6 37.2 28.3 27.5 21.3 45.4 29.5 35.8 22.1 37.8 29.1 28.4 21.7 25.1 47.1 24.7 41.1 25.4 33.7 25.9 24.2 26.0 26.9 25.9 25.7 26.0 26.7 24.2
10.5 7.7 8.3 5.9 8.7 6.6 6.4 5.0 10.7 7.8 8.3 6.1 8.9 6.8 6.6 5.1 6.9 11.2 5.7 9.7 5.8 8.6 6.2 5.5 6.1 6.2 6.4 6.1 6.6 6.4 6.6
92.7 96.2 92.8 95.1 93.5 96.0 92.2 96.0 95.1 98.3 94.5 97.6 95.0 98.6 95.2 97.6 97.3 91.8 96.7 96.1 97.1 97.3 97.0 90.8 96.5 97.0 97.2 96.8 96.1 97.2 96.4
Table 3. Coefficients of the Regression Equation and Results of Statistic Analysisa
b0 b1 b2 b3 b4 b11 b22 b33 b44 b12 b13 b14 ) b23 ) b24 ) b34 ) 0 R Sreg2 freg Sresidual2 fresidual F(R2) R(F, freg, fresidual) Sadeq2 fadeq Srepeat2 Frepeat F R(F, fadeq, frepeat) standard deviation of the mean standard deviation
selectivity of the transformation to MAA Y1
selectivity of the transformation to DAA Y2
selectivity of the transformation to TAA Y3
AC conversion Y4
-36.0099 3.3405 7.7599 495.6897 2.8055 -0.0379 -0.4360 -1631.9048 -0.4074 -0.0339 -7.7500
96.1093 -2.3658 -6.1827 -426.1115 1.9994 0.0254 0.3439 1445.9524 -0.2213 0.0247 7.0250
21.4778 -0.5324 -1.3495 -92.2651 0.8357 0.0068 0.0674 346.1905 -0.1211 0.0067 0.8000
79.2091 0.4426
0.9987 260.0427 11 3.8555 19 67.4474
