2-(2-甲氧基乙氧基)乙醛二乙醇缩醛的合成工艺研究

将金属钠溶解于乙二醇单甲醚生成钠盐后立即与溴代乙醛二乙醇缩醛反应,合成了半合成大环内酯类抗生素的重要中间体２ （２ 甲氧基乙氧基） 乙醛二乙醇缩醛,避免了旧有工艺需使用价格昂贵且危险性较高的原料氢化钠的缺点。采用正交实验法得到最佳反应条件：金属钠与溴代乙醛二乙醇缩醛的物质的量比为１∶１－５,溶剂的量为０－３６ ｍＬ／ｍｍｏｌ,反应时间为１０ ｈ,产物的收率为９１－７ ％ 。新工艺易于控制,成本较低,适于工业生产。     

2-(2-甲氧基乙氧基)乙醛缩二甲醇的合成

以乙二醇-甲醚为起始原料,与金属钠进行取代反应,不经分离,与2-氯乙醛缩二甲醇经缩合反应合成2-(2-甲氧基乙氧基)乙醛缩二甲醇,同时考察反应时间、醇钠物质的量比和醛钠物质的量比对收率的影响。反应的最佳条件为：反应时间8h,醇钠物质的量比为4：1,醛钠物质的量比为1．3：1,收率为90％。     

乙酰乙醛缩二甲醇的合成

介绍了适合工业化的乙酰乙醛缩二甲醇合成路线.丙酮、甲醇钠与甲酸甲酯反应得乙酰基乙烯醇钠,再与硫酸氢甲酯反应得到目标产物,收率可达71.8%.     

2,2-二甲氧基乙醇的合成

以甘油、丙酮为起始原料,经羟基保护、去丙酮叉、缩醛化、催化氢化5步反应合成了标题化合物,总收率22%,其结构经过红外光谱、核磁共振氢谱确证.与文献相比,反应条件温和,操作简便.     

2,4-二甲氧基甲氧基苯乙酸的合成

以2,4-二甲氧基苯乙酸为原料,经由4步反应合成了2,4-二甲氧基甲氧基苯乙酸。对目标分子和得到的中间体进行了¹H-NMR、MS表征,为合成香豆素类染料提供了新的前体化合物。     

2,2-二甲氧基乙胺的制备

2,2-二甲氧基乙胺(4)是重要的有机合成中间体。以乙酸乙烯酯为起始原料,经过溴化、Gabriel合成、肼解合成了目标产物,3步反应总收率63.8%。产品经1H NMR和质谱表征。改进后的方法具有操作简单、成本低、反应时间短等优点。     

3,5-二甲氧基邻苯二甲酸酐的合成

以2,4-二甲氧基-6-甲基苯甲酸乙酯为原料,经溴代、水解、氧化、环合、还原5步反应,合成了金丝桃素的中间体,即标题化合物。其结构经~1HNMR和~(13)CNMR表征。     

3,4-二甲氧基苯乙醛的合成研究

以3,4-二甲氧基苯甲醛为原料,经Darzens缩合、碱解、脱羧得到3,4-二甲氧基苯乙醛,反应总收率为61.5%。通过对反应溶剂、反应时间的考察和优化,改进后的合成工艺操作更加方便、更加快捷、更适合工业化生产。     

3,4-二甲氧基苯胺的合成

以3,4-二甲氧基苯为原料。在0-5℃低温条件下,以硝酸和硫酸按比例配成的混酸进 行硝化,反应结束后过滤得到3,4-二甲氧基硝基苯,该步反应的收率有97％。然后以乙醇为溶剂, 雷尼镍为催化剂,在1．6 MPa的氢气压力下,于高压釜中100℃条件下通过催化加氢将3,4-二甲氧 基硝基苯还原为3,4-二甲氧基苯胺。该反应的收率达到90％以上,纯度达到98％以上。     

3，4-二甲氧基苯乙酸的新法合成

以3,4-二甲氧基苯甲醛为原料,经Knoevenagel反应、硼氢化钾选择性还原、再在酸性条件下氧化反应获得3,4-二甲氧基苯乙酸。通过探讨其反应机理优化了合成条件,并采用高效液相色谱,红外光谱,核磁共振等检测手段确认了产物结构与纯度,各步总产率为62．6％。该反应原料易得,操作简单,收率较高,避免了使用剧毒试剂,更适合于工业生产。     

生物质材料木材胶粘剂的研究进展

大豆蛋白作为一种廉价、易得、资源丰富、环境友好的生物质材料受到了广泛的关注,为了解决豆蛋白胶自身易水解、易受微生物侵蚀的缺陷,化学改性豆蛋白被广泛采用,以贻贝胶为模板对豆蛋白、木素等生物质材料进行化学改性用于制备木材胶粘剂也是研究的热点,本文对这2方面的研究进展做了简要的回顾。     

Characterization of canola oil based polyurethane wood adhesives

A novel bio-based poly (ether ester) polyol containing both primary and secondary functional groups was synthesized from canola oil using a low cost and efficient procedure. In this work, use of the new canola oil derived polyol for the production of polyurethane (PU) adhesives was demonstrated. The canola oil based PU adhesives had similar or better adhesive properties in terms of lap shear strength than three commercial PU adhesives. The effect of NCO/OH ratio and temperature on adhesive characteristics on wood bonding was also evaluated by lap shear tests. It was found that the use of an elevated curing temperature (i.e. 100 °C), as well as optimized NCO/OH molar ratio (higher than 1.5/1.0), improved the wood adhesive properties. The overall chemical resistance of bio-based PU adhesives to cold water, acid and alkali was comparable to that of commercial PU adhesives whilst its resistance to hot water was superior.     

生物基木材胶粘剂

具体介绍了几种重要生物基木材胶粘剂,包括木素、单宁、大豆蛋白、淀粉、木质生物质液化产物胶粘剂、热解生物油胶粘剂等的研究进展情况。分析了生物基木材胶粘剂的应用现状,指出了生物基木材胶粘剂存在的问题,并对其发展方向进行了展望。     

葛根淀粉基胶黏剂制备与性能研究

研究开发以淀粉为主要原料的环保型胶黏剂替代"三醛类"木材胶黏剂,对彻底解决人造板及其制品的甲醛释放问题具有重要意义。以野生葛根淀粉为原料,通过降黏处理,并与聚醋酸乙烯酯和异氰酸酯复配,制备出胶合强度达到国家Ⅱ类要求的淀粉基木材胶黏剂。研究了降黏剂用量、降黏时间、聚醋酸乙烯酯和异氰酸酯用量对淀粉基木材胶黏剂胶合强度的影响。优化工艺条件下制备胶黏剂胶接胶合板的胶合强度为1.89 MPa,能够满足国家Ⅱ类胶合板强度要求。     

Lignin‐based polycondensation resins for wood adhesives

Lignin‐based wood adhesives are obtained that satisfy the requirements of relevant international standards for the manufacture of exterior‐grade wood particleboard. Formulations based on low molecular mass lignin and presenting an increase in the relative proportion of reactive points yield better results than the higher molecular mass lignin used in the past. These lignins allow a higher proportion of hydroxymethylation during preparation of methylolated lignins. These lignin‐based adhesives also yield acceptable results at particleboard pressing times that are sufficiently low to be of industrial significance. Lignin‐based wood adhesives, in which a nonvolatile nontoxic aldehyde (glyoxal) is substituted for formaldehyde in their preparation, are prepared and tested for application to wood panels such as particleboard. The adhesives yield good internal bond strength results for the panels, which are good enough to comfortably pass relevant international standard specifications for exterior‐grade panels. The adhesives also show sufficient reactivity to yield panels in press times comparable to that of formaldehyde‐based commercial adhesives. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1690–1699, 2007     

乙烯基乳液-异氰酸酯木材胶粘剂的研究

介绍了一种乙烯基乳液－异氰酸酯木材胶粘剂,探讨了配方中主要成分对胶粘剂性能的影响。该胶具有良好的胶接性、耐水性。     

Effect of water on some wood adhesives

As part of a programme to study the water durability of adhesively bonded wood, the effect of water on some formaldehyde-condensate adhesives for wood has been examined at temperatures between 4 and 75°C. The diffusion coefficients and levels of water uptake have been measured for urea-, melamine- and phenol-resorcinol-formaldehyde adhesives, and for some spruce adherends. The effect of water on tensile strengths has been studied for urea-formaldehyde adhesives.     

木材胶粘剂的研究进展

介绍了三醛胶和白乳胶的改性研究进展,综述了近年来出现的新胶种以及可再生资源在胶粘剂中的利用,并对木材胶粘剂的发展进行了展望.     

Morphologic accessibility of wood adhesives

Accessibility of wood adhesives was determined using a potassium bromide-embedding technique during resin cure. Cured resin was then extracted with water, followed by x-ray analysis of residual potassium bromide retention in the adhesive matrix. Cured urea–formaldehyde (UF), phenol–formaldehyde resol (PF), and phenol–resorcinol formaldehyde (PRF) accommodated large quantities of potassium bromide. However, only PRF adhesive showed crystallization of trapped potassium bromide, suggesting the presence of large pore sizes in the polymer lattices. Both UF and PRF adhesives, after room-temperature soaking, were equally resistant to water access. At higher temperature, water accessibility of UF increased greatly which may be attributed to thermal softening of the adhesive, while the accessibility of water to the PRF adhesive matrix was mainly a surface phenomenon and was not very temperature dependent. PF was highly accessible to water, even at room temperature, as a result of swelling from the presence of sodium hydroxide (catalyst). Accessibility of PRF adhesive was greatly increased by base (NaOH) solutions but not by acid (H₂SO₄) solutions. The UF resin showed slight increase of accessibility with increase in acidity and basicity of the water solution, but the accessibility increase of this adhesive in base solution was substantially less than that of PRF. The acid hydrolysis influence on accessibility increase of UF adhesive was far less severe than that of temperature.