基于1-甲基-2,4-苯二脲路径的尿素法合成甲苯-2,4-二氨基甲酸甲酯反应研究

采用尿素法合成甲苯-2,4-二氨基甲酸甲酯(TDC)是一条绿色的工艺路线.其反应路径之一是以1-甲基-2,4-苯二脲(TBU)为中间产物,即2,4-二氨基甲苯(TDA)与尿素反应生成TBU,TBU再与甲醇反应得到TDC.首先对该路径进行了热力学分析,然后分别对两步反应进行了研究.对于TBU合成反应,适宜溶剂和催化剂分别为环丁砜(CBS)和乙酸锌;适宜反应条件为:反应温度130℃,反应时间7 h,n(TDA):n(Zn(OAc)2):n(Urea):n(CBS)=1:0.05:3.5:10.此时TDA转化率为54.3%,TBU选择性为73.3%.对于TDC合成反应,基于液相色谱-质谱和气相色谱分析结果,确定了反应组分.适宜的反应条件为:反应温度140℃,反应时间5 h,反应压力1.1 MPa,甲醇与TBU摩尔比为110:1.在该反应条件下,TBU转化率为100%,TDC选择性为60.4%.     

合成甲苯-2,4-二氨基甲酸甲酯反应体系的热力学分析

由2,4 二氨基甲苯与碳酸二甲酯制备甲苯 2,4 二氨基甲酸甲酯为一复合反应体系。本文用基团贡献法计算了该反应体系的反应热、吉布斯自由能变化、化学反应平衡常数。对反应原料中甲醇的含量对甲苯 2,4 二氨基甲酸甲酯收率的影响进行了计算。计算数据与文献值及试验结果比较,表明计算结果可靠,对实验室研究及工业生产都有重要的指导意义。     

Carbon2Polymer: A CO2-based Route to Polyurethanes via Oxidative Carbonylation of TDA with Methyl Formate

The Carbon2Polymer project involves a multistep reaction sequence for the non-phosgene synthesis of the high-value polymer precursor toluene-2,4-diisocyanate (TDI) starting from carbon dioxide. The present study of the oxidative carbonylation revealed that for the intermediate toluene-2,4-dicarbamate (TDC) the productivity is highest with Pd@ZrO₂, followed by Pd@CeO₂. As one of the side products which are formed in parallel and consecutive reactions the methylene-bridged dimer “TDCCH2TDC” (5) has a promising potential for industrial application.     

Precious-Metal-Decorated Chromium(IV) Oxide Nanowires as Efficient Catalysts for 2,4-Toluenediamine Synthesis

The catalytic hydrogenation of 2,4-dinitrotoluene (DNT) to 2,4-toluenediamine (TDA) is a key step in the production of polyurethanes; therefore, the development of efficient hydrogenation catalysts for industrial use is of paramount importance. In the present study, chromium(IV) oxide nanowires were decorated by palladium and platinum nanoparticles in a one-step, simple, and fast preparation method to yield highly efficient hydrogenation catalysts for immediate use. The nanoparticles were deposited onto the surface of CrO₂ nanowires by using ultrasonic cavitation and ethanol as a reduction agent. Beneficially, the catalyst became catalytically active right at the end of the preparation and no further treatment was necessary. The activity of the Pd- and Pt-decorated CrO₂ catalysts were compared in the hydrogenation of 2,4-dinitrotoluene (DNT). Both catalysts have shown high activity in the hydrogenation tests. The DNT conversion exceeded 98% in both cases, whereas the 2,4-toluenediamine (TDA) yields were 99.7 n/n% and 98.8 n/n%, with the Pd/CrO₂ and Pt/CrO₂, respectively, at 333 K and 20 bar H₂ pressure. In the case of the Pt/CrO₂ catalyst, 304.08 mol of TDA formed with 1 mol Pt after 1 h hydrogenation. Activation energies were also calculated to be approximately 24 kJ∙mol⁻¹. Besides their immediate applicability, our catalysts were well dispersible in the reaction medium (methanolic solution of DNT). Moreover, because of their magnetic behavior, the catalysts were easy to handle and remove from the reaction media by using a magnetic field.     

Ni/硅藻土催化2,4-二硝基甲苯加氢反应研究

以Ni/硅藻土为催化剂,研究了2,4-二硝基甲苯(2,4-DNT)在2,4-二氨基甲苯(2,4-TDA)和乙醇混合溶剂中加氢生成2,4-TDA的反应历程,考察了反应温度、反应时间和氢气压力等条件对2,4-DNT加氢的影响。结果表明,反应温度和反应时间是影响2,4-DNT加氢的主要因素,最佳反应条件为:反应温度120～130℃、氢气压力2.5～3.0MPa,反应时间140min。     

植物生长调节剂2-(2,4-二氯苯氧基)三乙胺的合成新方法

以2,4 二氯苯酚为原料,采用相转移催化剂,经过醚化、胺化反应合成了2 (2,4 二氯苯氧基)三乙胺,总收率大于80%。研究了反应物的摩尔配比、反应时间及反应温度对2,4 二氯苯酚和二溴乙烷的醚化反应的影响,优惠工艺条件为:2,4 二氯苯酚与1,2 二溴乙烷配比为1∶30(mol/mol),反应温度80℃、反应时间10h。通过红外光谱、核磁共振氢谱和元素分析确定了目标化合物的结构。     

磺化硅胶催化合成2,4-滴丁酯

以2,4-二氯苯氧乙酸和正丁醇为原料,磺化硅胶为催化剂,催化合成除草剂2,4-二氯苯氧乙酸正丁酯(2,4-滴丁酯)。考察催化剂用量、原料配比及回流时间对反应的影响。结果表明,最佳反应条件为:催化剂用量为2,4-二氯苯氧乙酸质量的1.4%,n(正丁醇):n(2,4-二氯苯氧乙酸)=10:1,回流时间为1.0 h,2,4-二氯苯氧乙酸正丁酯的收率为98.7%。     

2-甲基-2,4-戊二醇的合成

介绍了由二丙酮醇在高压、加热条件下还原合成２－甲基－２,４－戊二醇。影响２－甲基－２,４－戊二醇的收率的因素有：压力、温度、催化剂用量、反应时间及搅拌次数等。通过实验得出如下最佳工艺条件：压力３．０ＭＰａ,温度９５℃～１０５℃,催化剂用量１０％,反应时间７ｈ,搅拌速率５５次／ｍｉｎ。     

甲基叔丁基醚与苯酚在改性HY分子筛催化剂上合成2,4-二叔丁基苯酚的研究

对改性HY分子筛催化剂研究表明,每种改性物均存在一个最佳含量．P2O5改性后HY催化剂的性能最优越。苯酚的转化率达99.60％,2,4-二叔丁基苯酚(2,4-DTBP)选择性达63.90％：这一结果是目前分子筛作催化剂合成(2,4-IDTBP)的最好结果,具有潜在的应用前景,采用常压连续流动固定床反应器,克服了釜式反应操作麻烦的缺点：使用HY分子筛催化剂,无污染、无腐蚀,为工业生产提供了艮好的环境、以MTBE做为烷基化试剂,使工业生产叔丁基苯酚可以因地制宜地扩大原料来源：MTBE价格低廉易得,运输方便,进而可以降低产品成本     

2,4-二氯苯氧乙酸烃基二甲硅基甲酯的合成及其生物活性

以三甲基氯硅烷、烃基溴化镁和２，４ 二氯苯氧乙酸为原料，经氯化、格氏反应、亲核取代和脱氯化钾等步骤，合成了一类新型植物生长调节剂———２，４ 二氯苯氧乙酸烃基二甲硅基甲酯和２，４ 二氯苯氧乙酸二乙基甲硅基甲酯，其结构经元素分析、ＩＲ和１ＨＮＭＲ表征。生物活化试验表明，与母体化合物２，４ 二氯苯氧乙酸相比，使柑桔产量提高７％。     

TDI/TiO_2有机无机纳米杂化材料的合成与表征

文章采用有机包覆法对纳米TiO2进行表面改性,制备了2,4-甲苯二异氰酸酯(TDI)/TiO2纳米杂化材料。采用红外光谱(FT-IR)、热质量损失分析(TGA)、静态接触角(CA)、透射电镜(TEM)及分散性实验等手段对纳米TiO2和TDI/TiO2纳米杂化粒子进行分析和表征。红外光谱和热质量损失分析显示,TDI以物理吸附和化学键合的方式存在于纳米TiO2的表面,并形成了有机包覆层。经计算,每nm2约有4.0个羟基参与化学反应,化学包覆率达57.97%。静态接触角数值表明,TDI/TiO2纳米杂化粒子具有很强的疏水性能,与水的接触角达147°。分散性实验显示,TDI/TiO2纳米杂化粒子在基础润滑油中分散稳定,静置20 d未出现分层现象。     

Catalytic synthesis of toluene‐2,4‐diisocyanate from dimethyl carbonate

The process for catalytic synthesis of toluene‐2,4‐diisocyanate (TDI) from dimethyl carbonate (DMC) consists of two steps. Starting from the catalytic reaction between toluene‐2,4‐diamine (TDA) and DMC, dimethyl toluene‐2,4‐dicarbamate (TDC) is formed, and then decomposed to TDI. For the first step, the yield of TDC is 53.5% at a temperature of 250 °C, over Zn(OAc)₂/α–Al₂O₃ catalyst. For the second step, the yield of TDI is 92.6% at temperatures of 250–270 °C and under pressure of 2.7 kPa, over uranyl zinc acetate catalyst, when di‐n‐octyl sebacate(DOS) is used as heat‐carrier, and a mixture of tetrahydrofuran (THF) and nitrobenzene is used as solvent. © 2001 Society of Chemical Industry     

2-(2,4-二氯苯氧基)-三乙胺的合成

在相转移催化条件下，首先用2,4-二氯苯酚与二氯乙烷反应制得1-氯-2-（2，4-二氯苯氧基）乙烷中间体，然后再与二乙胺反应，合成植物生长调节剂2-（2，4-二氯苯氧基）-三乙胺。其总收率为84．6％，含量为98．0％。     

3-氯-2,4-二氟苯甲酸的合成

提出了一种以2,6-氟苯胺为原料,经Sandmeyer反应、溴化和格氏反应三步得到3-氯-2,4-二氟苯甲酸的合成方法.其中Sandmeyer反应中氯代一步的最佳反应条件为:n(2,6二氯苯胺)∶n(氯化亚铜)=1 ∶0.55,氯代反应温度为70～90℃,氯代保温时间为2.5h.三步总摩尔产率约28％,纯度99.26 ...     

1-苯基-2,4-戊二酮的合成研究

以β-二酮与氨基钠反应,再与氯化二苯基碘反应得到1-苯基-2,4-戊二酮。     

4,5-二氢-3-甲基-1-(2,4-二氯苯基)-1,2,4-三唑-5(1H)酮的合成

乙酰亚氨酸甲酯盐酸盐与2,4-二氯苯肼在三乙胺的作用下生成2-(2,4-二氯苯基)酰肼乙烷亚胺酸。然后在光气中环合得到4,5-二氢-3-甲基-1-(2,4-二氯苯基)-1,2,4-三唑-5(1H)酮。反应总收率为90.6%(以2,4-二氯苯肼计),含量为98.9%。     

N-(5-氨基-2,4-二乙氧基苯基)苯甲酰胺的合成

以2,4-二乙氧基-5-硝基苯胺(DEANB)为原料,先经酰化反应得到N-(2,4-二乙氧基-5-硝基苯基)苯甲酰胺(DEBNB),最后经还原得到蓝色基BB的同分异构体N-(5-氨基-2,4-二乙氧基苯基)苯甲酰胺(DEBAB)。DEBNB的较佳合成条件:n(DEANB):n(苯甲酰氯)=1∶1.25,丙酮和水作溶剂,K2CO3作缚酸剂,反应温度0℃,反应时间1 h,收率90.95%,HPLC纯度98.35%;产品DEBAB的较佳合成条件:Fe粉为还原剂,n(DEBNB):n(铁粉)=1∶4,水和乙醇作溶剂,反应时间5 h,反应温度80℃,收率89.93%,HPLC纯度98.96%。     

2,4-二氯苯并噻唑的合成研究

以2-氨基-4-氯苯并噻唑为原料,在酸性条件下与亚硝酸钠反应,再水解生成2,4-二氯苯并噻唑。探讨了亚硝酸钠的用量、反应温度和反应时间3个因素对产物收率的影响,优化了合成工艺。在优化条件下,产品收率为91.9%,纯度达98.6%。     

2,4-二氯甲苯合成中氯化工序的技术改进

采用降低反应釜搅拌转速、改进通氯方式、降低反应温度等方法,改善了2,4-二氯甲苯合成的反应条件.反应时间由原来的24 h缩短为12 h,氯气利用率从81.6%提高到90.2%.氯化反应收率从52.3%提高到55.7%,产品纯度提高0.5个百分点;同时降低了消耗,减少了环境污染.     

Selective chlorination of 4-chlorotoluene to 2,4-dichlorotoluene over zeolite catalysts

The performance of various zeolites in the liquid phase chlorination of 4-chlorotoluene (4-CT) with gaseous chlorine at a moderate temperature and normal pressure has been examined. A comparison under the same conditions with Lewis acid catalyst FeCl₃, is also carried out. It is found that zeolite K-L exhibits higher selectivity for 2,4-dichlorotoluene (2,4-DCT/3,4-DCT = 3.54) compared to the other zeolites studied and also FeCl₃ catalyst (2,4-DCT/3,4-DCT = 3.18), while the rate of 4-CT conversion (75.8 mmol g^–1 h^–1) is found to be comparable on K-L and FeCl₃ catalysts. The highest rate of 4-CT conversion, among the catalysts studied is obtained over K-beta (101.4 mmol g^–1 h^–1). FeCl₃ catalyst produces higher amounts of tri- and tetra-substituted products due to its non-shape-selective character. Mainly the side-chain chlorinated product (,4-dichlorotoluene) is obtained over K-X, amorphous SiO₂ and in the absence of catalyst. Solvents influence the rate of 4-CT conversion as well as the 2,4-DCT/3,4-DCT isomer ratio. 1,2-dichloroethane appears to be the best solvent in enhancing the 2,4-DCT/3,4-DCT isomer ratio when the reaction temperature is raised from 313 to 353 K.