本文主要研究内容
作者常硕（2019）在《多糖基非均相催化剂的制备及其在C-X键构筑中的应用》一文中研究指出：Ullmann偶联反应是目前构建C-X键的重要方法之一,在医药和农化领域起着至关重要的作用。然而早期的Ullmann反应需要苛刻的条件,比如高温、强碱、过量的铜盐等,这些条件极大地限制了Ullmann反应的应用。后来配体的引入突破了上述的限制,反应条件也更加温和。但是,随之出现了配体不易回收和催化成本过高等问题,目前更多的科研人员开始了对非均相催化剂的研究。在非均相催化剂载体材料中,壳聚糖作为一种廉价易得的天然高分子聚合物,自身含有与金属中心螯合的配位官能团,是一种天然的良好配体。本文对壳聚糖作为Ullmann偶联反应的催化剂载体进行了如下探究:本文对壳聚糖分子结构中的氨基基团进行化学修饰以增加载体与金属螯合的活性位点。通过模板反应发现壳聚糖经二吡啶甲醛改性后负载CuI用于催化反应中,产物收率可达99%。对Ullmann反应条件中碱源、温度和溶剂的考察,从而得到了最佳的反应体系:Cs2CO3作为碱源、DMSO为溶剂、于110oC反应24 h。并在该最优条件下对底物进行了扩展,证实该催化体系具有广泛的底物适应性。考察了催化剂的循环使用性能,发现该催化剂重复使用5次后用于模板反应中仍能保持90%以上收率。紧接着对催化剂进行了SEM、TG、XRD、EDS、XPS等一系列表征,结果表明,二吡啶甲醛壳聚糖衍生物中N原子上自由电子对与铜离子能形成稳定的配位键,经多次催化反应后,铜浸出量少,因而催化剂循环使用性能较好。虽然二吡啶甲醛官能化壳聚糖铜盐配合物具有优异的催化效果以及循环使用性,但是在回收过程中粉末状催化剂仍然面临着重量的损失。因此本文通过利用壳聚糖溶胶-凝胶特性,将其溶于稀醋酸中利用pH反转从而制备出壳聚糖微球。加入交联剂既引入了一些螯合性能更强的配体官能团,同时又极大地提高了微球的机械强度。将微球分别与多种铜盐形成铜盐配合物,用于Ullmann型C-N偶联反应中。通过对一系列条件因素的考察,得到最佳催化体系为乙二醛交联壳聚糖微球负载CuI、Na2CO3作为碱源、水作为溶剂、在100oC下反应24 h。对微球催化剂进行了一系列表征,发现微球经交联后形成了三维网状结构,同时在200 oC以下具有较好的稳定性。最后考察了微球催化剂重复使用性能,通过简单的过滤回收,该催化剂重复使用5次后,重量损失16%,铜含量损失33%,重复使用10次后,产物的收率仍在65%以上。目前广泛用于催化Ullmann反应的铜源主要是一价铜,本文发现壳聚糖负载的零价铜在水相中仍然具有较好的催化效果,并且零价铜形貌可控,同时避免了一价铜在空气中易氧化的缺点。首先利用壳聚糖自身所带基团的还原性将二价铜还原成零价铜,避免使用硼氢化钠等试剂作为还原剂,同时SEM检测出生成的零价铜尺寸为200 nm左右并且分散均匀。通过XPS分析得知零价铜与壳聚糖上氨基基团形成了稳定的配位键。在最优催化条件下将该催化剂用于水相中的Ullmann反应中,发现该催化剂具有广泛的底物适应性,并且重复使用5次后仍能保持优异催化效果。
Abstract
Ullmannou lian fan ying shi mu qian gou jian C-Xjian de chong yao fang fa zhi yi ,zai yi yao he nong hua ling yu qi zhao zhi guan chong yao de zuo yong 。ran er zao ji de Ullmannfan ying xu yao ke ke de tiao jian ,bi ru gao wen 、jiang jian 、guo liang de tong yan deng ,zhe xie tiao jian ji da de xian zhi le Ullmannfan ying de ying yong 。hou lai pei ti de yin ru tu po le shang shu de xian zhi ,fan ying tiao jian ye geng jia wen he 。dan shi ,sui zhi chu xian le pei ti bu yi hui shou he cui hua cheng ben guo gao deng wen ti ,mu qian geng duo de ke yan ren yuan kai shi le dui fei jun xiang cui hua ji de yan jiu 。zai fei jun xiang cui hua ji zai ti cai liao zhong ,ke ju tang zuo wei yi chong lian jia yi de de tian ran gao fen zi ju ge wu ,zi shen han you yu jin shu zhong xin ao ge de pei wei guan neng tuan ,shi yi chong tian ran de liang hao pei ti 。ben wen dui ke ju tang zuo wei Ullmannou lian fan ying de cui hua ji zai ti jin hang le ru xia tan jiu :ben wen dui ke ju tang fen zi jie gou zhong de an ji ji tuan jin hang hua xue xiu shi yi zeng jia zai ti yu jin shu ao ge de huo xing wei dian 。tong guo mo ban fan ying fa xian ke ju tang jing er bi ding jia quan gai xing hou fu zai CuIyong yu cui hua fan ying zhong ,chan wu shou lv ke da 99%。dui Ullmannfan ying tiao jian zhong jian yuan 、wen du he rong ji de kao cha ,cong er de dao le zui jia de fan ying ti ji :Cs2CO3zuo wei jian yuan 、DMSOwei rong ji 、yu 110oCfan ying 24 h。bing zai gai zui you tiao jian xia dui de wu jin hang le kuo zhan ,zheng shi gai cui hua ti ji ju you an fan de de wu kuo ying xing 。kao cha le cui hua ji de xun huan shi yong xing neng ,fa xian gai cui hua ji chong fu shi yong 5ci hou yong yu mo ban fan ying zhong reng neng bao chi 90%yi shang shou lv 。jin jie zhao dui cui hua ji jin hang le SEM、TG、XRD、EDS、XPSdeng yi ji lie biao zheng ,jie guo biao ming ,er bi ding jia quan ke ju tang yan sheng wu zhong Nyuan zi shang zi you dian zi dui yu tong li zi neng xing cheng wen ding de pei wei jian ,jing duo ci cui hua fan ying hou ,tong jin chu liang shao ,yin er cui hua ji xun huan shi yong xing neng jiao hao 。sui ran er bi ding jia quan guan neng hua ke ju tang tong yan pei ge wu ju you you yi de cui hua xiao guo yi ji xun huan shi yong xing ,dan shi zai hui shou guo cheng zhong fen mo zhuang cui hua ji reng ran mian lin zhao chong liang de sun shi 。yin ci ben wen tong guo li yong ke ju tang rong jiao -ning jiao te xing ,jiang ji rong yu xi cu suan zhong li yong pHfan zhuai cong er zhi bei chu ke ju tang wei qiu 。jia ru jiao lian ji ji yin ru le yi xie ao ge xing neng geng jiang de pei ti guan neng tuan ,tong shi you ji da de di gao le wei qiu de ji xie jiang du 。jiang wei qiu fen bie yu duo chong tong yan xing cheng tong yan pei ge wu ,yong yu Ullmannxing C-Nou lian fan ying zhong 。tong guo dui yi ji lie tiao jian yin su de kao cha ,de dao zui jia cui hua ti ji wei yi er quan jiao lian ke ju tang wei qiu fu zai CuI、Na2CO3zuo wei jian yuan 、shui zuo wei rong ji 、zai 100oCxia fan ying 24 h。dui wei qiu cui hua ji jin hang le yi ji lie biao zheng ,fa xian wei qiu jing jiao lian hou xing cheng le san wei wang zhuang jie gou ,tong shi zai 200 oCyi xia ju you jiao hao de wen ding xing 。zui hou kao cha le wei qiu cui hua ji chong fu shi yong xing neng ,tong guo jian chan de guo lv hui shou ,gai cui hua ji chong fu shi yong 5ci hou ,chong liang sun shi 16%,tong han liang sun shi 33%,chong fu shi yong 10ci hou ,chan wu de shou lv reng zai 65%yi shang 。mu qian an fan yong yu cui hua Ullmannfan ying de tong yuan zhu yao shi yi jia tong ,ben wen fa xian ke ju tang fu zai de ling jia tong zai shui xiang zhong reng ran ju you jiao hao de cui hua xiao guo ,bing ju ling jia tong xing mao ke kong ,tong shi bi mian le yi jia tong zai kong qi zhong yi yang hua de que dian 。shou xian li yong ke ju tang zi shen suo dai ji tuan de hai yuan xing jiang er jia tong hai yuan cheng ling jia tong ,bi mian shi yong peng qing hua na deng shi ji zuo wei hai yuan ji ,tong shi SEMjian ce chu sheng cheng de ling jia tong che cun wei 200 nmzuo you bing ju fen san jun yun 。tong guo XPSfen xi de zhi ling jia tong yu ke ju tang shang an ji ji tuan xing cheng le wen ding de pei wei jian 。zai zui you cui hua tiao jian xia jiang gai cui hua ji yong yu shui xiang zhong de Ullmannfan ying zhong ,fa xian gai cui hua ji ju you an fan de de wu kuo ying xing ,bing ju chong fu shi yong 5ci hou reng neng bao chi you yi cui hua xiao guo 。
论文参考文献
论文详细介绍
论文作者分别是来自江南大学的常硕，发表于刊物江南大学2019-10-21论文，是一篇关于反应论文,非均相催化剂论文,壳聚糖论文,改性论文,循环使用论文,江南大学2019-10-21论文的文章。本文可供学术参考使用，各位学者可以免费参考阅读下载，文章观点不代表本站观点，资料来自江南大学2019-10-21论文网站，若本站收录的文献无意侵犯了您的著作版权，请联系我们删除。