|
1. |
Infrared study of the surface reaction of gaseous sulphuryl chloride with metal carboxylates |
|
Journal of the Chemical Society, Perkin Transactions 2,
Volume 1,
Issue 1,
1983,
Page 1-4
Shigeaki Nakamura,
Preview
|
PDF (526KB)
|
|
摘要:
J. CHEM. soc. PERKIN IXANS. 11 I983 Infrared Study of the Surface Reaction of Gaseous Sulphuryl Chloride with Metal Carboxylates Shigeaki Nakamura Department of Chemistry, Takamatsu Technical College, Takamatsu City 761,Japan The surface reaction of metal carboxylates RC02M (R = H, Me, Et, Pr", and Pr'; M = Li, Na, and K) with gaseous sulphuryl chloride has been monitored by i.r. spectroscopy. Reactions (I) and (11) take place. 2RCO2M + SO,CI, +RCOMSO, -+ RCOCl + MCI (1) Process (I) is observed for all carboxylates except the formates and the lithium salts at 18-30 "C. Sodium acetyl sulphate is formed at room temperature by process (I). After removal of CH,COCI formed in process (I) and SO2CI2, when the mixture is heated to 150 "C, it reacts further with the carboxylate to give the anhydride and sodium sulphate.In case of potassium acetyl sulphate, when the mixture is heated to 150"C after the removal of CH3COCI and SO2CI2, it gives some ester and K2CO'O'S03 in addition to the anhy- dride. Process (TI) occurs for the formates and the lithium salts at room temperature. In the case of the reaction of the formates at room temperature, formyl chloride as the product reacts immediately with sodium and potassium formate to give formic anhydride and with lithium formate to yield formic acid. At 150 "C, all the carboxylates mainly react with sulphuryl chloride according to process (II), and the acyl chloride as product reacts with the carboxylates except the formates to form the anhydride, and the formate to give formic acid.However, in the reaction of potassium acetate at 150 "C, some of the acetyl sulphate as product decomposes with the acetate to give K2CO*O*S03, methyl acetate, and carbon mon- oxide. This suggests that the process (I) takes place to some extent at 150 "C. Some sulphuryl chloride reactions take place at moderate temperatures in the presence of aluminium chloride, benzoyl peroxide, or 1ight.l In addition, organic compounds such as phenol or polymethoxybenzenes react with sulphuryl chloride at room temperature in the absence of catalysts. This is con-sidered to proceed through ionic or polar forms of sulphuryl chloride.2 The reactions of sulphuryl chloride have been so far studied for the liquid phase. I report here the surface reaction between sulphuryl chloride and metal carboxylates to help clarify steric and electronic effects at the solid-gas interface.The sulphuryl chloride-sodium acetate system 3-5 was considered to proceed according to reactions (1)-(3). Subsequently, secondary 2CH3C02Na+ SO2CI2-2CH3COCI + Na2S04 (I) 2CH3C02Na+ SO2CI2-+ CH3COC1 -t CH3CONaS04+ NaCl (2) 2CH3CO2Na+ S02C12+ (CH3C0J2S02-t2NaCI (3) reactions occur and the acid anhydride is formed as final product. For reactions (1)-(3) it is considered that the transitions states (I)-(111) are formed. In this work, the influence of these transition states on the reaction of gaseous sulphuryl chloride with metal carboxylates is discussed. Experimental In the reaction of carboxylates with gaseous sulphuryl chloride, a Pyrex i.r.tube (950 ml) was used. A film of alkali metal (Li, Na, and K) was evaporated onto an NaCl plate and the wall of the reaction tube by heating and destroying a small glass tube, in which purified alkali metal was placed, with a 0 0 0 II II II R-C-0'-Mf R-C-0-Mf R-C-0' M+ 0 0 R = alkyl M = metal tungsten filament at 10 Torr. A small amount of purified carboxylic acid was degassed, subjected several times to trap-to-trap distillation, and introduced into the i.r. tube equipped with a stopcock. The gaseous acid formed the carboxylate (ca. 1.5 mmol) on contact with the alkali-metal film. The tube was placed in a Hitachi 215 spectrophotometer, evacuated, and heated to 150 "C for 2 h to remove any water and remaining carboxylic acid completely.Then, one of three courses was pursued. In the first, after returning the apparatus to the desired temperature 18-31 or 150 "C, purified sul- phuryl chloride (0.652m~) was admitted to the tube and reaction occurred. The i.r. spectra of the thin solid layer of the reacted carboxylate and the gaseous phase were taken at various times. In the second procedure, after reaction by the first route at room temperature, the apparatus was again evacuated for 3 h at room temperature to remove residual gaseous reactants and the gaseous products formed on the successive introduction of sulphuryl chloride (0.39m~), the carboxylic acid (0.874m~), the anhydride (0.39m~), or alternatively, the acyl chloride (0.874m~).The i.r. spectra of 2 J. CHEM. SOC.. PERKIN TRANS. I1 1983 Y' I I1 I I1 I I1 2000 1600 1200 800 v/c m-' Figure 1. 1.r. spectra for the surface reaction of sodium acetate with gaseous sulphuryl chloride at 27 T:A, solid layer of sodium acetate; B, solid layer 30 min after injection of gaseous sulphuryl chloride (0.652m~);C, solid layer heated to 150 "Cafter evacuation ; D, gas phase after the surface reaction ; E, gaseous acetyl chloride at room temperature; F, gaseous acetic anhydride at room temperature the solid and gas phases were measured for 30 min. In the third procedure, as in the second route, after reaction at room temperature, the apparatus was evacuated for 3 h at room temperature to remove gaseous substances, and then heated to 150 "C after evacuation.The i.r. spectra of the solid and gas phases were obtained by heating and were measured for 30 min at I50 "C. The reaction times at various temperatures for the first route were determined as follows: formates at 18-30 "C, HCOzLi 30, HCOzNa 230, HC02K 213 min; acetates at 22-28 "C, MeC02Li 350, MeCOzNa 30, CD3CO2Na38, MeC0,K 20 min; propionates and butyrates at 19-31 "C, EtC0,Li 51, EtC0,Na 9, Pr"COzNa 10, PriCOzNa 10 min; carboxylates at high temperature (60 and 150 "C), HCO2Li 43 (in this case only at 60 "C), HC0,Na 32, HCOzK 13, MeC0,Li 26, MeC02Na 42, MeC02K 9 min. At 18-31 "C, the frequencies of the i.r. absorption spectra for each reaction exhibited nearly constant values independent of the tempera- ture. Reaction with sulphuryl chloride was allowed to con- tinue until variation in vasym(C=O) became negligible.The gaseous products such as acetic anhydride and acetyl chloride were identified by comparing the i.r. spectra with pure samples obtained by g.1.c. (Shimadzu Type GC-6 AM). A 3 x 2 000 rnrn column (Triton X-305, Chromosorb 101) was used at 70 and 150 "C with a helium flow rate of 40 ml min-'. Table 1. 1.r. frequencies of solid phase for the reaction of gaseous sulphuryl chloride with carboxylates CD,C02Na + MeCOzNa + MeCO2K+ Reaction sc * sc sc TIT 28 150 150 tlmin 38 42 9 vlcm-' 2 320w -A-- ---~___ 7 2 240vw 2 160vw I800sh 1 740m I 730w I 560s 1410s 1300sh 1300vw 1 260s I270m 1 150s I 150s I 130m 1 100s I 100s 1080w 1040sh 1030m 1 ooovw 1 OOOsh 925w 90Ovw 880w 840m 830sh 790w 760w 735m 735w "SC -gaseous sulphuryl chloride.Results and Discussion As shown in Figure 1 A, the i.r. absorption spectra of a thin layer of sodium acetate are measured before reaction. The bands vary greatly for the 30 min after the injection of gaseous sulphuryl chloride at 27 "C. New main bands for the solid phase appear at 1 740, 1 370, 1 260, I 120, I 055, 1 005, 900, and 745 cm- (Figure I B). The apparatus was evacuated for 3 h at 27--65 "C after the reaction; however, the intensities and frequencies of the solid- phase bands remain constant throughout evacuation (Figure 1 B).Further, when gaseous sulphuryl chloride (0.39m~), acetic acid (0.874m~),or acetic anhydride (0.39m~) was introduced into the reaction tube at 27 "C the solid-phase bands are little affected. However, the intensities of the solid- phase bands of the acetate were decreased on adding gascous acetyl chloride (0.874m~) at 27 "C, and i.r. absorption bands corresponding to those of acetic anhydride appear in the gas phase. The bands in the solid phase near 1 120 cm increase gradually in strength on heating to 150 "C (Figure lC), and in the gas phase acetic anhydride is mainly formed. The other bands decrease in contrast with the bands near 1 120 cm-'. After heating, the presence of sulphate ions in the solid phase was ascertained by the usual method.Accordingly, the strong band near 1 120 cm-' is assigned to the degenerate stretching vibration of sulphate ion.6 As shown in Figure lD, the characteristic bands of acetic anhydride appear at 1 820 and 1 770 cm-l [v (GO)], and of acetyl chloride at 1 820, 1 800 [v (C=O)], and 960 cm-I [v (C-C) -t6 (CH3)].7 Bonds at 1 430 and ca. 1 200 cm-' were from residual sulphuryl chloride and those at ca. 1 361 and 1 150 cm-l were assigned to sulphur dioxide * from the decom- position of sulphuryl chloride. In the case of the reaction of so-dium [2H3]acetate (Table l), the bands at l 740, l 260, l 130, J. CHEM. SOC. PERKIN TRANS. I1 1983 Table 2.Yields of main gaseous products in the reaction of gaseous sulphuryl chloride with carboxylates Carboxylate used (mmol)Sulphuryl chloride used (mM) T/"Ctlmin Conversion (%) Composition of gaseous products (%I = Formic acid Formic anhydride Carbon monoxide Sulphur dioxide Non-reacted sulphuryl chloride Acetic acid Acetyl chloride Acetic anhydride Methyl acetate HC02Li HC0,Na HCOzK MeC02Li MeCOzNa MeCOzK (1.5)0.652 0.652(1.5) (1.5)0.652 0.652(1.5) (1.5)0.652 (1.5)0.652 R.t." R.t.R.t. R.t. 150 R.t. 150 R.t. 150 30 230 213 350 26 30 42 20 9 20 83 78 38 84 47 100 95 99 10.2 td t 54.2 51.4 0.2 t 0.7 9.6 7.5 8.3 18.7 14.8 14.7 18.5 11.1 18.6 80.0 38.2 40.0 31.3 18.7 35.6 1.4 5.0 5.2 6.5 5.5 45.0 27.3 28.9 61.3 22.4 75.0 58.7 67.0 8.2 R.t.= room temperature, 18--31 "C. The conversion was estimated by the vasym(C=O)absorbance of the solid carboxylate before and after the reaction. The composition was estimated by i.r. spectroscopy and g.1.c. t = trace. and 735 cm correspond to those of the MeC0,Na reaction in Figure IB, and also those for the reaction of EtC02Na, Pr"CO,Na, PriC02Na, and MeC02K. These bands are due to the frequencies of CO and SO groups and are almost inde- pendent of the alkyl groups and alkali metal ions. The band near I740 cm-' is assigned to v (GO) of the acetyl group because the i.r. spectra of acetic acid and its derivatives adsorbed on silica powder are characterized by v (GO) I 760-1 740 ~m-'.~ This band is shifted to higher frequency than the unperturbed frequency due to the interaction between the CO and SO4 groups in CH3CONaS04.Clemett et af. reported that v (GO) in CH3COS04H is observed at 1 798 or 1 785 cm-' in solution." Since the present v (GO) is observed in the solid state, it is considered that the surround- ing field effects will contribute to the difference between our frequency and those of Clemmet et af." In the case of the reactions of CD3C02M, EtC02M, Pr"C02M, and Pr'C0,M (M = Na and K) with gaseous sulphuryl chloride, the absorp- tion bands near 1 740 cm-I are assigned to v (GO) of the acyl groups. In addition, the strong, broad band at 1 260 cm ' is assigned to vasym(SOZ)in CH3CONaS04. This band is the degenerate stretching frequency of the SO3-group in CH3COS0,-, and is shifted to a lower frequency than that of the sulphones." However, this is a higher frequency than those of sodium methanesulphonate and ethanesulphonate, 1 202 and 1 193 cm-l,lz showing the effect of the CH,CO group on vasym(S02)in CH3COS04-.The bands near 1 120 and 1055 cm-' correspond to vSy,(SO2) in CH3COS04- as judged by the linear relationship between vaSy,and vSy,of the SO, group,13 and by the spectra of the sodium salt of methane- sulphonic acid and alkyl trifluoromethane~ulphonates.~~The bands near I 005 and 745 CM-' (Figure 1B) are assigned to v (C-0) and v (S-0) of the c-o-so3-group. From the i.r. bands, gaseous sulphuryl chloride on reaction with solid sodium acetate initially forms sodium acetyl sulphate, acetyl chloride, and acetic anhydride.The reaction is hindered by an increase in sodium acetyl sulphate concentra- tion, and thus some sulphuryl chloride remains unreacted. The acetyl chloride produced in this reaction reacts further with the residual acetate to give the anhydride. This process also takes place in the reaction of gaseous sulphuryl chloride with carboxylates such as EtCO,Na, PrnCOzNa, and PriC02Na at room temperature. A mixture of sodium acetate and acetyl sulphate gives rise to acetic anhydride on heating at 150 "C. On the other hand, gaseous sulphuryl chloride reacts completely with solid acetate in 42 min at 150 "C to form the anhydride and sodium sulphate (Tables 1 and 2).The molar ratios of sodium acetate used and acetic anhydride formed to sulphuryl chloride consumed in the reaction are found to be ca. 4: 1 and 2: 1. These reactions at room tem-perature are represented by equation (4). Some RCOCl formed undergoes the secondary reaction (5) with residual RC02M. A mixture of RCOMSO, and RC02M reacts on 2RC02M + S02C12 RCOMSO, -+ RCOCl + MCl (4) R = Me, Et, Pr", Pr' M=Na,K RCOCl + RCOZM (RC0)ZO + MC1 (5) RCOMSO, + RC02M (RCO),O + M2S04 (6) heating at 150 "C as in equation (6). The reaction of gaseous sulphuryl chloride with carboxylates at 150 "C proceeds by 4RC02M + S02C12 + 2(RC0),0 + M2S04 + 2MC1 (7) equation (7). For reaction (7), two processes are considered. The first forms the.anhydride as the final product via the steps shown below.Judging from the results of the reaction of potassium acetate at 150 "C (Tables 1 and 2), some acetyl sulphate reacts with the acetate to give KzCO*O-S03 (bands at 1 730, 1 270, 1 150, 1 040, and 735 cm-'), methyl acetate, and carbon monoxide. The second process doesn't follow reaction (4), but occurs through (8) instead, and further gives 2RCOzM + S02C12 2RCOCl + M2S04 (8) the anhydride via reaction (5). The second process occurs for the reactions of gaseous sulphuryl chloride with the lithium salts (MeC02Li and EtC02Li) and with the formates (HC02Li, HC02Na, and HC0,K) at room temperature. The difference between the first and second route can be explained by the two transition states (1) and (11).If the readion prefers $ I T=10% C .c. .-4 E a-e+ 4000 3000 2000 1600 1200 800 v/cm-' Figure 2. 1.r. spectra for the surface reaction of sodium formate with gaseous sulphuryl chloride at 20 "C:A, solid layer of sodium formate; B, solid layer 230 min after injection of gaseous sulphuryl chloride (0.652m~);C, gas phase after the surface reaction the transition state (II), RCOCl, RCOMS04, and MCl are first formed in reactior, (4), and then the anhydride through reactions (5) and (6). On the other hand, in transition state (I), sulphuryl chloride and carboxylate are first transformed into RCOCl and M2S04by reaction (8) and RCOCl reacts immedi- ately with RC02M in a secondary reaction (5) to give the corresponding anhydride.Figure 2 shows the i.r. absorption spectra for the reaction of gaseous sulphuryl chloride with solid sodium formate at 20 "C. The bands vary gradually for 230 min after injection of gaseous sulphuryl chloride. The broad band at 1 120 cm-I appears immediately after the start of the reaction and its intensity increases greatly (Figure 2B). As described for the reaction of sodium acetate, the strong, broad band near 1 120 cm-I is assigned to the sulphate ion. New weak bands at 1 720,1400,l 305, and 720 cm-I appear (Figure 2B). These bands are in agreement with those for the solid phase of sodium formate on exposure to gaseous formic acid, and disappear on evacuation. Accordingly, a small amount of formic acid is considered to be formed in the solid phase.As shown in Figure 2C, the bands at 1 820, 1 800, 1 770, 1 755, 1 095, 1 000, and 985 cm-l correspond to formic anhydride and are stable for several hours in dry air or helium at 20 "C. Upon contact with water vapour, the bands immediately change into those of formic acid. From these i.r. spectra, in the surface reaction of gaseous sulphuryl chloride with solid sodium formate at 20 "C, sodium formyl sulphate is not formed at all, whereas formyl chloride and sodium sulphate are formed immediately. Formyl chloride is rapidly converted into formic anhydride because of its lability. This process is the same as that of the second path described for the reactions of sulphuryl chloride with acetate at 150 "C [(8) and (5)], and proceeds through the transition state (I). Potassium formate and gaseous sulphuryl chloride at 18 "C J.CHEM. SOC. PERKIN TRANS. I1 1983 react similarly. For lithium formate at room temperature, formic anhydride is not produced at all, while formic acid and a small amount of carbon monoxide are formed (No. 1 in Table 2). Accordingly, reaction (9) first takes place. Sub- 2HCOzM + S02C12 -2HCOCl+ MzS04 (9) sequently, a secondary reaction occurs to give the anhydride from the sodium or potassium salt and formic acid from the lithium one. The occurence of another process is indicated by the fact that the yield of carbon monoxide is smaller than that of formic acid at room temperature (Table 2) and C02 and SO2are formed to a substantial degree at 150 "C.In conclusion, gaseous sulphuryl chloride and solid alkali- metal carboxylates react through the two transition states (I) and (II), in which there is an interaction between the electro- philic sulphur atom of sulphuryl chloride and nucleophilic oxygen of the carboxylates. For formates there is a lowering of the steric hindrance on the solid surface and an enhanced positive charge on the carbon atoms of the carbonyl groups compared with the other esters. Accordingly, gaseous sulphuryl chloride is converted into HCOCl and M2S04through the transition state (L). References 1 0. Silberrad, J. Chem. SOL'.,1922, 121, 1015; M. S. Kharasch and H. C. Brown, J. Am. ChePn. SOC.,1940, 62, 925; 2393; M. Ballester, C.Molinet, and J. Castaner, ibid., 1960, 82, 4254; T. Nagai, K, Nishitomi, and N. Tokura, Tetrahedron Lett., 1966, 2419. 2 R. Bolton and P. B. D. de la Mare, J. Chem. SOC.B, 1967, 1044; A. J. Banister, J. A. Durrant, J. S. Padley, and K. Wade, J. fnorg. Nucl. Chem., 1979, 41, 1415; D. Masilamani and M. M. Rogic, J. Org. Chem., 1981, 46, 4486. 3 J. T. Hewitt and C. H. Lumsden, J. SOL'.Chem. Ind., 1916, 35, 210. 4 I. Ichikizaki, ' Comprehensive Organic Chemistry, Aliphatic Compounds 111,' Asakura, Tokyo, 1974, vol. 4, p. 259. 5 A. .I.Van Peski, Red. Trav. Chim. Pays-Bas, 1921, 40, 103; S. Hannes and L. Lauri, Papier, 1964, 18, 600. 6 T. Shimanouchi, ' Analysis of Infrared Spectra,' Nankodo, Tokyo, 1960, p. 90. 7 P. Mirone, B. Fortunato, and P. Canziani, J. Mol. Struct., 1970, 5, 283; J. Overend, R. A. Nyquist, J. C. Evans, and W. J. Potts, Spectrochim. Acta, 1961, 17, 1205. 8 S. Mizushima and T. Shimanouchi, ' Infrared Absorption and Raman Effect,' Kyoritsu, Tokyo, 1971, p. 156. 9 R. P. Young, Can. J. Chem., 1969, 47,2237. 1OC. J. Clemett, J. Chem. SOC.B, 1971, 2202; E. Monotoneri, M. Fornaroli, L. Giuffre, E. Tempesti, and G. Sioli, J. Chem. Sac., Perkin Trans. 2, 1976, 1784. 11 D. Barnard, J. M. Fabian, and H. P. Koch, J. Chem. Soc., 1949, 2442; K. C. Schreiber, Anal. Chem., 1949, 21, 1168. 12 M. St. C. Elett, Spectrochim. Ada, 1962, 18, 1537. 13 E. A. Robinson, Can. J. Chem., 1961,39, 247. 14 T. Granstad, J. Chem. SOC.,1957,4069. 15 H. Kuhne, T. K. Ha, R. Meyer, and H. H. Gunthard, J. Mol. Spectrosc., 1979, 77,251. Received 21st September 1981;Paper 1/1469
ISSN:1472-779X
DOI:10.1039/P29830000001
出版商:RSC
年代:1983
数据来源: RSC
|
|