Polymer Journal, Vol. 22, No. 11, pp 969-975 (1990) Preparation of Styrene Derivatives Containing Sulfide Group: Addition Reactions of Thiophenol and Its Derivatives to 1,4-Divinylbenzene Eiichi KOBAYASHI,* Jian JIANG, Hiroyoshi MATSUMOTO, and Junji FURUKAWA Department of Industrial Chemistry, Faculty of Science and Technology, Science University of Tokyo, Noda, Chiba 278, Japan (Received April 13, 1990) ABSTRACT: To prepare styrene derivatives containing a sulfide group such as 4-vinyl-1- [(2-phenylthio)ethyl]benzenes, the addition reactions ofthiophenols to 1,4-divinylbenzene were car­ ried out in the presence of AIBN or BPO. The maximum yields of the corresponding adducts were about 62% by the G.C. method. The competitive addition reaction of thiophenol to 1,4- divinylbenzene and the remaining vinyl group of the mono-adduct simultaneously took place to decrease the yield of the mono-adduct. The effects of the reaction time, reaction temperature and the additive in the course of the reaction are discussed based on gas chromatographic studies. The monomer reactivity ratio of the obtained mono-adduct was estimated by the radical copolymerization with MMA. KEY WORDS Addition Reaction / Thiophenol / 1,4-Divinylbenzene / p-Arylthioalkylstyrene / 4-Vinyl-1-[(2-phenylthio )ethyl]benzene / 4-Vinyl- 1-[(p-tolylthio)ethyl]benzene / 4-Vinyl-1-[(m-tolylthio )ethyl]benzene / Co­ polymerization / Monomer Reactivity Ratio / Many kinds of styrene derivatives containing kylthiomethylstyrene or arylthiomethylstyrene characteristic functional groups have been by a condensation reaction of chloromethyl­ synthesized and used to prepare new advanced styrene with sodium alkyl sulfide or sodium materials. For instance, Tsuruta et at.1- 3 phenyl sulfide. The polymers composed of the studied the addition reactions of various sulfide monomers were highly reactive against amines to divinylbenzene by a lithium alkyl­ an electron beam to develop a positive pattern. 8 amide catalyst to prepare styrene derivatives On the other hand, the addition reaction of containing amine groups. The copolymeriza­ a thiol group to an unsaturated carbon-carbon tion with styrene was carried out to prepare bond, which yields anti-Markownikoff type copolymers with a sea-island microstructure or adducts in the presence of a radical initiator, a lamellar microdomain which was found to is well known. 9 - 11 Screttas et al. carried out be effective for antithrombogenic materials. the addition reaction of thiophenol to olefin Nakahama et a/_ 4 - 5 reported also the prep­ and diolefin to synthesize sulfide derivatives. 12 aration of styrene derivatives containing silyl Another kinetic approach to the addition· groups. The silyl group was used to protect reaction of thiophenol to styrene showed13•14 the reactive functional groups in the mono­ that the reaction rate depends on the mers toward anionic living polymerization concentration of thiophenol. The rate de­ of styrenes. Asahara et al. 7 prepared al- termining step is the hydrogen transfer from * To whom all correspondence should be addressed. 969 E. KOBAYASHI, J. JIANG, H. MATSUMOTO, and J. FURUKAWA thiophenol to the intermediate carbon radical. However, few investigations have been con­ ducted to prepare new styrene derivatives by the addition reaction. The authors developed a new synthetic method for styrene derivatives containing a sulfide group by the addition reaction of thiophenol (TP) and its derivatives to 1,4- divinylbenzene (DVB) (Scheme l ). 0 60 120 300 500 700 900 Reaction Time, min. CH,=CH-@-CH=CH, + HS-@x _!!:__. Figure I. Relationship between reaction time and yield I of 2a in benzene at 75°C under nitrogen atmosphere. [DVB] =[la] =0.34 moll- 1; [Initiator]=2.0x 10- 3 la, X=H 0 0 mo! I- 1 . AIBN; L, AIBN plus 1.87 ppm oxygen added lb, X=p-Me e, against total monomer; D, BPO; O, without initiator. le, X=m-Me CH,=CH-@-CHz-CHrS-@X equipped with a three-way stopcock under 2 nitrogen atmosphere. The reaction solution 2a, X=H was colorless transparent from the beginning 2b, X=p-Me 2c, X=m-Me to the end of the reaction. As shown in Figure l, the yield of 2a Scheme 1. measured by G.C. method was significantly affected by the initiation mode. In the presence In this paper, the authors deal with (i) of the radical initiators, AIBN and BPO, the synthesis of styrene derivatives containing a yield of 2a rapidly increased up to about 65%, sulfide group, 2a, 2b, and 2c, (ii) elucidation however, it remained about 20% without of the reaction mechanism, and (iii) the adding any initiator. A small amount of oxygen copolymerization of 2a with methyl methacry­ initiated the addition reaction, but a large late and the estimation of Q and e values of amount of oxygen decreased the yield of 2a as the monomer 2a. discussed later. The yield of 2a reached a maximum of about 62% for 60min, then de­ RESULTS AND DISCUSSION creased gradually with reaction time. After the reaction was stopped, 2a was isolated with two Addition Reactions of Thiophenol and Its methods, column chromatography or distilla­ Derivatives to DVB tion under reduced pressure. For details, see Addition reaction mechanisms of thiophe­ EXPERIMENTAL. The isolated yield of 2a was nols to styrenes are already examined in this about 50%. laboratory. 15 Here, addition reactions of 1 H NMR spectrum of the isolated 2a is thiophenols to DVB are extensively studied to shown in Figure 2. There appeared three main obtain 2a, 2b, and 2c. To synthesize new styrene peaks, characterized as absorptions of benzene derivatives containing a sulfide group, an rings (6.7-7.l ppm, 9H), vinyl goup (4.9-6.6 addition reaction of la with DVB was carried ppm, 3H) and methylene (2.6-3.2 ppm, 4H) out at 75°C in benzene in the presence of small of2a. In addition, no signals assignable to other amount of initiators such as AIBN and BPO. structures than 2a could be detected; e.g., no An equimolar amount of la and DVB with a absorption peaks at 1.5 ppm and 3.5 ppm small amount of the radical initiator was assigned for the methylene and methine of charged into a 50 ml round bottom flask polymers of DVB arid 2a, respectively. In the 970 Polym. J., Vol. 22, No. II, 1990 Addition Reaction of Thiophenol to Divinylbenzene CH2=CH-@-CH2-CH2-S-@x 2a - phenyl X=H vinylene methylene r--:-7 TMS 2b methyl X=p-Me ,..,.,2c X=m-Me 4000 3000 2000 1600 1200 800 400 98765432 o ppm cm- 1 Figure 2. 1H NMR spectra of 2a, 2b and 2c, in CDCl3 . TMS as standard. Figure 3. IR spectra of 2a, 2b, and 2c. Liquid film method. 1 H NMR spectra of 2b and 2c, besides the absorptions of benzene rings (6.7-7.1 ppm), I~ 2R· (1) vinyl group (4.9-6.6ppm), and methylene R· + TP-2.L_. </JS·+ RH (2) (2.6-3.2 ppm), the characteristic methyl peaks ka1 • r/JS· + DVB - CH,=CH<pCH-CH,-S-<p (3) appear at 2.2 ppm. 1 Figure 3 shows the IR spectrum of 2a. The CH,=CHq>CHCH,S<p+TP ktr CH,=CH<pCH,CH,S<p+ <pS• (4) characteristic absorption peaks of the meth­ 2a Scheme 2. ylene group at 2940 and 2850 cm - 1 , the strong absorption peaks of the vinyl group at 1630, 980, and 900 cm - 1 , as well as the p-substituted With the repetition of reactions (3) and (4), and mono-substituted benzene rings appear at the product 2a was produced successively by 820 and 730 cm- 1 , respectively. With the the chain reaction. The reaction scheme is comparison of the observed sulfur content of already discussed based on the kinetic 2a, 13.3% (Calcd 13.3%), it is clearly explained method. 16 However, the product 2a possesses that the addition reaction of la to DVB is the reactive vinyl group toward thiophenol la capable of producing a novel styrene derivative and active species for the polymerization. containing the sulfide group, 2a. In the IR Accordingly, DVB simultaneously turns into spectra of 2b and 2c, besides the absorption products 2a and 3a as shown in Scheme 3. peaks appeared in the IR spectrum of 2a, Indeed, the addition reaction of two moles of methyl absorptions newly appear at 2995 and la with one mole of DVB was reported to give 1380cm- 1 . the 3a quantitatively. 12 Polymerization of DVB The addition reaction of la to DVB took and 2a would reduce also the yield of 2a, if it place in the radical chain mechanism shown occurred. However, only a small amount of in Scheme 2, where I means a radical initiator. polymers was recovered, since thiophenol can Polym. J., Vol. 22, No. 11, 1990 971 E. KOBAYASHI, J. JIANG, H. MATSUMOTO, and J. FURUKAWA act as an effective chain transfer reagent to prevent polymerizations. 17 Consequently, the formation of the di-adduct 3a may be the main factor to reduce the yield of the mono-adduct 2a. ka2 • r/JS· + 2a----, r/JSCH,CHr/JCH,CH,Sr/J (5) • ktr2 r/JSCH,CHr/JCH,CH,Sr/J + TP--- r/JSCH,CH,r/JCH,CH,Sr/J +</JS· 0""-------'----~---~~ 0 60 120 180 3a (6) Reaction Time, min. Scheme 3. Figure 4. Relationship between yield of 2a and reaction temperature in benzene under nitrogen atmosphere. e, 75°C; O, 65°C; t::,,, 55°C; [DVB]0 =[1a]0 =0.34 moU- 1; The thiophenol derivatives, p-toluenethiol [AIBN]=2.0x 10- 3 mo11- 1. and m-toluenethiol also reacted with DVB to give the corresponding novel adducts, 2b and 2c with about 50% of the isolated yield. These addition reactions behave quite the same as that of la with DVB.