第26卷第2期常州大學(xué)學(xué)報(bào)(自然科學(xué)版)Vol 26 No. 22014年4月Journal of Changzhou University (Natural Science Edition)Apr.2014文章編號(hào):2095-0411(2014)02-0004-03對(duì)溴甲苯的合成工藝朱國(guó)彪,奚旺(常州大學(xué)江蘇省精細(xì)石油化工重點(diǎn)實(shí)驗(yàn)室,江蘇常州213164)摘要:以甲苯、液溴為原料,在催化劑存在下直接溴化可制得溴代甲苯?？疾炝瞬煌瑴囟取⒎磻?yīng)時(shí)間、催化劑組成和溶劑比對(duì)反應(yīng)的影響,得到最佳反應(yīng)條件:以5A分子篩和I2作為催化劑,甲苯和二氯甲烷溶劑體積比為2:1,10℃下反應(yīng)6h,甲苯轉(zhuǎn)化率為77.8%,對(duì)溴甲苯收率達(dá)到752%對(duì)位異構(gòu)體選擇性可達(dá)96.6%.本實(shí)驗(yàn)確定的對(duì)溴甲苯合成的工藝路線原料來(lái)源廣泛,價(jià)格低廉,反應(yīng)工藝條件溫和,3廢少,工業(yè)化前景廣閥關(guān)鍵詞:對(duì)溴甲苯;溴化;催化劑;對(duì)位選擇性中圖分類號(hào):TQ612.2文獻(xiàn)標(biāo)識(shí)碼:Adol:10.3969/issn.2095-041l2014.02.002a Study on the Synthesis of 4-BromotolueneZHU Guo-biao, XI Wang(iangsu Key Laboratory of Fine Petrochemical Engineering, Changzhou University, Changzhou 213164China)Abstract: The bromotoluene was prepared by toluene and liquid bromine as raw materials over catalystsThe effects of different temperature, time, catalysts and solvent ratio were investigated. The best reac-tion conditions were selected: using 5A molecular sieve and I2 as the catalyst, the volume ratio of tolueneand methylene chloride was 2: 1, reacted for 6h at 10C, the conversion of toluene reached 77.8%,theyield of 4-bromotoluene reached 75. 2%, the paraisomer selectivity reached 96. 6%. The raw materials ofthis reaction are cheap and widely used, the conditions of this reaction is mild and it has less three wastesit has broad prospects for industrialization.Key words: 4-bromotoluene; bromination; catalyst; para-selectivity溴甲苯包括鄰、間、對(duì)3種異構(gòu)體,是重要的藝產(chǎn)品收率較低,原料價(jià)格較貴。甲苯直接溴化報(bào)精細(xì)化工中間體,廣泛應(yīng)用于醫(yī)藥、農(nóng)藥及染料等道較多的為催化溴化5,催化劑采用沸石體系,合成工業(yè)中口。對(duì)溴甲苯主要通過(guò)甲苯的直接溴代也有甲苯經(jīng)溴化鈉溴化制備對(duì)溴甲苯的文獻(xiàn)[7]和對(duì)甲苯胺重氮鹽的桑德邁爾反應(yīng)兩種方法合報(bào)道。本文考察了以5A分子篩和I2為催化劑在不成可用于制造對(duì)溴溴芐、對(duì)溴二溴芐和對(duì)溴同條件下對(duì)甲苯定向溴化的影響苯甲醛等中間體,同時(shí)對(duì)溴甲苯也是抗高血壓藥物1 santa的原料。以對(duì)甲苯胺為原料先進(jìn)行重氮1實(shí)驗(yàn)部分化再采用桑德邁爾反應(yīng)反應(yīng)來(lái)合成對(duì)溴甲苯,該工稿日期:2013-10-10。作者簡(jiǎn)介:朱國(guó)彪(1964-),男,江蘇海門人,副教授,主要從事精細(xì)TYH中國(guó)煤化工CNMHG朱國(guó)彪,等:對(duì)決甲苯的合成工藝產(chǎn)物中多溴甲苯含量也會(huì)升高,對(duì)甲苯溴化不利。1.1試劑與儀器實(shí)驗(yàn)確定的最佳反應(yīng)溫度為10℃。甲苯、液溴、氫氧化鈉、亞硫酸氫鈉、碘粒由圖2可知,由于在低溫下反應(yīng),反應(yīng)較緩鐵粉、二氯甲烷均為分析純,5A分子篩(顆粒度和,副反應(yīng)不多且溴素?fù)]發(fā)少,隨著反應(yīng)時(shí)間的增為3~5mm,堆積密度≥0.65g/mL,有效物質(zhì)含加,對(duì)溴甲苯收率不斷提高,在4h之后,反應(yīng)趨量≥98%)。于平緩,沒(méi)有明顯提高,實(shí)驗(yàn)確定最佳反應(yīng)時(shí)間為SP-6890型氣相色譜儀(山東魯南瑞虹化工4h,對(duì)溴甲苯收率為74.6%。儀器有限公司)、SHZ-DⅢ循環(huán)水式真空泵(鞏義市予華儀器有限責(zé)任公司)、DHG-9140A型電熱恒溫鼓風(fēng)干燥箱(上海精密實(shí)驗(yàn)設(shè)備有限公司)。1.2實(shí)驗(yàn)操作在250mL四口燒瓶中加入一定量的甲苯、5A分子篩、I2和溶劑,攪拌并在一定溫度下滴加液溴,滴加完繼續(xù)攪拌反應(yīng)約2h以上,直至無(wú)尾氣產(chǎn)生,反應(yīng)產(chǎn)生的溴化氫尾氣用氫氧化鈉水溶液吸收,實(shí)驗(yàn)樣品用氣相色譜進(jìn)行分析。反應(yīng)時(shí)間h2結(jié)果與討論圖2反應(yīng)時(shí)間對(duì)溴化反應(yīng)的影響Fig. 2 The influence of different time on the bromination reaction2.1甲苯定向溴化工藝條件2.2甲苯定向溴化催化劑溴化溫度和時(shí)間是影響溴化反應(yīng)的最重要的因溴甲苯異構(gòu)體中,對(duì)溴甲苯的用途用量及市場(chǎng)素。溴化溫度對(duì)甲苯溴化反應(yīng)影響結(jié)果見(jiàn)圖1,確銷售價(jià)格較大,實(shí)驗(yàn)主要以5A分子篩、I2和鐵粉定最佳溫度后,研究了溴化時(shí)間對(duì)溴化反應(yīng)的影為催化劑,對(duì)甲苯直接溴化反應(yīng)生成對(duì)位異構(gòu)體的響,結(jié)果見(jiàn)圖2。實(shí)驗(yàn)條件:甲苯100mL,液溴選擇性進(jìn)行了研究,結(jié)果見(jiàn)圖3,不同催化體系下49mL,I2和5A分子篩適量,液溴滴加時(shí)間約甲苯轉(zhuǎn)化率、對(duì)溴甲苯選擇性及收率見(jiàn)表1(實(shí)驗(yàn)3h,滴加完反應(yīng)3~4h,取樣分析。條件同上)。5A分子篩2和5A分子篩鐵粉℃℃℃℃反應(yīng)時(shí)間h反應(yīng)時(shí)間h圖1不同溫度對(duì)溴化反應(yīng)的影響圖3不同催化劑體系下對(duì)位選擇性比例Fig. 1 The influence of different temperature on the bromination reFig 3 The influence of different catalysts on the para-selectivity由圖3可知,在I2和5A分子篩的存在下,溴由圖1可見(jiàn),在10℃左右,對(duì)溴甲苯的收率化反應(yīng)中對(duì)位楫性后庇時(shí)回增加而增大,最在前3h并不高,但隨著反應(yīng)時(shí)間的增加,對(duì)溴甲終可達(dá)到的引入,其擇苯的收率可達(dá)到75.2%。在高溫下,反應(yīng)劇烈且形性對(duì)反CNMHG近獻(xiàn),且對(duì)極性6常州大學(xué)學(xué)報(bào)(自然科學(xué)版)2014年分子的吸附比非極性分子的強(qiáng),生成的對(duì)溴甲苯更對(duì)位選擇性的比例最高,反應(yīng)6h可達(dá)96.6%,若容易從吸附位上脫附,而以5A分子篩和L2單獨(dú)作溶劑量太少,不能保證甲苯和溶劑充分接觸,而量為催化劑時(shí),反應(yīng)6h條件下,對(duì)位選擇性為太大,使溴化劑和甲苯的濃度太低,對(duì)甲苯溴化帶78.3%和62.2%。以鐵粉為催化劑時(shí),選擇性低,來(lái)不利影響,造成浪費(fèi)并增加能耗。實(shí)驗(yàn)還研究了對(duì)位選擇性為56.4%,延長(zhǎng)反應(yīng)時(shí)間對(duì)增加對(duì)位正己烷、鄰二氯苯等溶劑條件下,對(duì)位選擇性均低選擇性無(wú)明顯變化。于二氯甲烷的結(jié)果。實(shí)驗(yàn)確定的溶劑為二氯甲烷,衰1不同催化劑體系下對(duì)溴化反應(yīng)的影響%溶劑體積比為2:1。Table 1 The influence of different catalysts on the brominationreaction3結(jié)論催化體系甲苯轉(zhuǎn)化率對(duì)位選擇性對(duì)溴甲苯收率(1)實(shí)驗(yàn)研究確定的甲苯溴化對(duì)位選擇性最佳5A分子篩70.278.3工藝條件為:5A分子篩和L2適量,甲苯和液溴以5A分子篩和I277.862.251.8物質(zhì)的量比為1:1進(jìn)行投料,甲苯和二氯甲烷以鐵粉98.1564553體積比為2:1投料,10℃下,滴加液溴約3h,滴由表1可見(jiàn),以鐵粉為催化劑時(shí),甲苯的轉(zhuǎn)化加結(jié)束繼續(xù)反應(yīng)3~4h(2)5A分子篩和L2作為催化劑,可以提高對(duì)率最高,可達(dá)到98.1%,鐵粉在反應(yīng)中形成中間態(tài)產(chǎn)物FeBr3,屬于酸催化劑,有利于反應(yīng)進(jìn)行,溴甲苯的選擇性,優(yōu)于鐵粉催化劑,甲苯轉(zhuǎn)化率達(dá)到78%,溴甲苯收率可達(dá)75.2%,對(duì)位選擇性但是選擇性低,鄰溴甲苯的含量較高。在溶液中碘可達(dá)96.6%左右。與電子給體易于形成電荷轉(zhuǎn)移配合物,促進(jìn)反應(yīng)順(3)本實(shí)驗(yàn)確定的溴甲苯合成的工藝路線原料利進(jìn)行,提髙甲苯轉(zhuǎn)化率,考慮到要提高對(duì)溴甲苯來(lái)源廣泛,價(jià)格低廉,NaBr可以通過(guò)后續(xù)處理進(jìn)的選擇性,因此選用5A分子篩和I2作為催化劑,行回收,因此該反應(yīng)工藝條件溫和,3廢少,產(chǎn)品對(duì)位選擇性可達(dá)到96.6%,收率為752%成本低,工業(yè)化前景廣闊。23甲苯定向溴化溶劑比鹵化反應(yīng)的溶劑也是影響反應(yīng)結(jié)果的重要因魯考文獻(xiàn):素。反應(yīng)溫度、時(shí)間、催化劑和溶劑的用量,直接[]李斌棟,呂春緒.溶劑法合成對(duì)溴甲苯[.淮海工學(xué)院學(xué)影響甲苯溴化反應(yīng)的原料甲苯轉(zhuǎn)化率和反應(yīng)產(chǎn)物的報(bào),2000,9(4):25-26對(duì)位選擇性。實(shí)驗(yàn)以5A分子篩和I2為催化劑,甲[2]高春香,楊希越,張靜,等.對(duì)溴甲苯的合成工藝研究[苯溴化反應(yīng)溶劑確定為二氯甲烷,不同溶劑比下甲遼寧化工,2007,36(2):73-74苯溴化反應(yīng)對(duì)位選擇性研究結(jié)果見(jiàn)圖4[3]張書文,侯林艷,潘雪靜,等.合成4(2)-溴代甲苯的新工藝研究[刀.化學(xué)工程師,2010(11):15-17[4]李紀(jì)國(guó),胡衛(wèi)華.高純度對(duì)溴甲苯[J].精細(xì)與專用化學(xué)品,一溶劑比2:12002(11):19-2溶劑比1[5] Esakkidurai T, Kumarraja M, Pitchumani K. Selectivity in一溶劑比3bromination of aromatic substrates by molecular bromine in thpresence of reusable zeolites [J]. Catalysis Letters, 2004(3-4):169-174.[6] Smith K, El- Hiti G A, Hammond M E w, et al. Highlymination reactions of simple aromatic compounds in the pres-ence of reusable zeolites [J]. Journal of the Chemical SocietyPerkin Transactions 1, 2000 (16): 2745-2752時(shí)間h[7] SadygovO A, Alimardanov K M, Chalabiev C A. Induced圖4不同溶劑比對(duì)對(duì)位選擇性的影響bromination of aromatic hydrocarbons with alkali metal bro-Fig 4 The influence of different solvent ratio on the para-selectivitmides in the presence of oxidants [J]. Russian Journal of Ap-由圖4可見(jiàn),甲苯與溶劑的體積比為2:1時(shí),中國(guó)煤化工CNMHG