TEMPO催化硫醇分子氧氧化偶联反应的研究

发布时间：2018-06-21 08:20

  本文选题：二硫化二苯并噻唑 + 氧化偶联　； 参考：《郑州大学》2017年硕士论文

【摘要】：随着人们环保意识的增强,绿色化学越来越受到化学家的关注。本论文将以绿色化学为原则,进行硫醇氧化偶联反应新方法的建立。氧气作为一种清洁无污染的氧化剂一直受到化学家的青睐,然而单纯的氧气对于许多的化学反应并不能起到直接的氧化作用,而是在反应中加入一些催化剂或者其他媒介来促使氧气参与到化学反应中去,从而起到氧化作用。TEMPO广泛的应用于催化氧化化学方面,尤其在醇的选择性催化氧化上最为出色,在催化硫醇氧化也展现出很好活性。在本文中,我们采用了一种高活性的有机小分子催化剂2,2,6,6-四甲基哌啶-N-氧自由基(TEMPO)来实现硫醇在分子氧下的氧化反应。硫-硫键的形成已经为人们所熟知,其在自然界也已经被发现存在于许多生物体内。S-S键在生物体中对于一些蛋白质的形成至关重要,同时也发现其在生物医药方面具有一些特殊的作用,例如一些具有硫硫键的化合物已经被发现具有抗肿瘤的特性,对于癌症的治疗具有重大意义。在工业上一些含有硫硫键的化学品如二硫化二苯并噻唑,已经用作硫化橡胶促进剂,且效果很好。还有具有S-S键的一些聚合物已经被研究用于可充电电池,并已经取得了一定的进展。在文中我们主要研究硫硫键的形成。为人们所熟知的硫化橡胶促进剂二硫化二苯并噻唑已经在工业上进行生产,在合成上采用的常见方法有次氯酸钠氧化,氯气氧化,亚硝酸钠氧化,双氧水氧化等,这些方法主要有一些缺点如反应条件不温和,反应过程有毒性金属试剂参与,反应后产生大量废液等。因此我们在研究中使用氧气这一绿色氧化剂,在反应中加入TEMPO作为催化剂,对二硫化二苯并噻唑的合成进行了一系列的研究,在实验过程中研究了反应温度、溶剂、催化剂用量、氧压、反应时间和反应浓度等因素对反应的影响。最终,反应最优条件确定为2-巯基苯并噻唑0.5 mmol,60℃,0.3 MPa氧压,5 mol%TEMPO催化剂,溶剂乙腈2 m L,反应时间4 h。反应收率达到97%。我们以构建S-S键为目标,接着又深一步进行了研究,对具备巯基的其他底物如芳基硫酚、杂环芳基硫酚、烷基硫酚进行其自身氧化偶联反应的研究,皆能得到中等到高产率的目标产物。鉴于对交叉偶联反应报道不多,我们对不同巯基底物进行了交叉偶联反应,研究发现芳基硫酚交叉偶联产率很高,烷基硫酚进行交叉S-S偶联得到中等产率。
[Abstract]:With the increasing awareness of environmental protection, green chemistry has been paid more and more attention by chemists. In this paper, a new method of oxidative coupling reaction of mercaptan will be established based on green chemistry. Oxygen has been favored by chemists as a clean and pollution-free oxidant. However, pure oxygen does not directly oxidize many chemical reactions. Instead, some catalyst or other medium is added to the reaction to induce oxygen to take part in the chemical reaction, thus providing oxidation. TEMPO is widely used in catalytic oxidation chemistry, especially in the selective catalytic oxidation of alcohols. It also showed good activity in catalytic mercaptan oxidation. In this paper, a kind of high activity organic small molecule catalyst 2O2O2O6O6 tetramethylpiperidine-N- oxygen free radical (TEMPO) was used to realize the oxidation of mercaptan under molecular oxygen. The formation of sulfur-sulfur bonds has been well known, and it has been found in nature that the. S-S bond in many organisms is essential for the formation of some proteins. At the same time, it has been found that it has some special functions in biomedicine. For example, some compounds with sulfur and sulfur bond have been found to have anti-tumor properties, which is of great significance for the treatment of cancer. Some chemicals containing sulfur and sulfur bonds, such as dibenzothiazole disulfide, have been used as accelerators for vulcanized rubber. Some polymers with S-S bond have been studied for rechargeable batteries and some progress has been made. In this paper, we mainly study the formation of sulfur and sulfur bonds. The accelerator of vulcanized rubber, dibenzothiazole disulfide, has been produced in industry. The common methods used in synthesis are sodium hypochlorite oxidation, chlorine oxidation, sodium nitrite oxidation, hydrogen peroxide oxidation and so on. The main disadvantages of these methods are that the reaction conditions are not mild, toxic metal reagents are involved in the reaction process, and a large amount of waste liquid is produced after the reaction. Therefore, we used oxygen as a green oxidant and TEMPO as catalyst to study the synthesis of dibenzothiazole disulfide. The reaction temperature and solvent were studied. The effects of catalyst dosage, oxygen pressure, reaction time and reaction concentration on the reaction were investigated. Finally, the optimum reaction conditions were determined as follows: 2-mercaptobenzothiazole 0.5 mmol / L 60 鈩，

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