乳酸薄荷酯的合成研究

以乳酸和薄荷醇直接反应制备乳酸薄荷酯,通过对乳酸薄荷酯制备的物料用量比、反应时间进行研究,获得了最佳的工艺条件:酸与醇的物质的量比为1.3:1,反应温度为110℃,反应时间为4 h,以对甲苯磺酸为催化剂,以环己烷为溶剂进行冷凝回流,产率为78.5%。反应液经过减压蒸馏之后,再进行重结晶,其质量分数能达到98.6%。乳酸薄荷酯具有独特的清凉效果,温和而持久,产品气味淡而清香,将其代替薄荷脑作为清凉剂应用于日用品的添加剂。     

戊二酸单薄荷酯合成工艺的研究

薄荷醇和戊二酸酐在催化剂4-二甲氨基吡啶(DMAP)的作用下,以甲苯为溶剂,合成新型清凉剂戊二酸单薄荷酯。采用单因素法优化了合成条件,得到较佳反应条件为:戊二酸酐和薄荷醇的物质的量比为1.5∶1,催化剂用量为薄荷醇的10%(物质的量分数),回流温度下反应10 h,收率在80%以上。     

L-乳酸薄荷酯的合成

以薄荷醇和L-乳酸为原料,用环已烷带水、经酯化、精制得到L-乳酸薄荷酯,并研究了反应时间、醇酸摩尔比、催化剂量对反应的影响,确定的优惠工艺条件为:n(薄荷醇)∶n(L-乳酸)=1.2∶1.0,催化剂为原料总重量2%,环己烷加热回流带水,反应6h,减压蒸馏至120℃/400Pa。残余物重结晶,得白色针状结晶产品,收率80%以上,纯度达到99%。     

尼龙酸薄荷酯的合成及其热裂解

以尼龙酸和L-薄荷醇为原料合成了清凉剂尼龙酸薄荷酯,采用单因素实验优化了合成工艺,并对产物的主要成分进行了分析和结构表征;利用热重-微商热重(TG-DTG)和在线裂解气相色谱/质谱联用(Py-GC/MS)法分别对尼龙酸薄荷酯的热失重和热裂解行为进行了考察。得到最佳合成条件为:当尼龙酸酐的投料量为0.1mol时,催化剂4-二甲氨基吡啶(DMAP)的用量为尼龙酸酐质量的0.4%、反应温度为70℃、反应时间为9.0 h、薄荷醇和尼龙酸酐的摩尔比为1.2∶1、环己烷用量50 mL,在该条件下产品收率达到89.3%。尼龙酸薄荷酯在301.5℃时失重速率最快为-19.17%/min,341.6℃时总失重率为99.72%;在300~450℃下尼龙酸薄荷酯的主要裂解产物为L-薄荷醇,随着裂解温度的提高,薄荷醇的释放量降低。     

乳酸异十三酯的合成

文章以乳酸和异十三醇为原料,直接酯化合成了乳酸异十三酯,考察了催化剂、酸醇比、带水剂的用量和反应时间对转化率的影响,通过红外光谱和气质联用仪对产品进行了结构表征。实验证明,硫酸氢钾具有较高的催化活性,最佳反应条件为:硫酸氢钾用量为乳酸和异十三醇总量的1%,带水剂用量为30 mL,乳酸和异十三醇的摩尔比为1.7∶1,反应时间为4 h,异十三醇转化率达91.77%。     

负载型对甲苯磺酸催化合成乙二醇硬脂酸单酯

探讨了以负载型对甲苯磺酸为催化剂合成乙二醇硬脂酸单酯的工艺。研究了醇酸摩尔比、催化剂用量、带水剂用量、反应时间等因素对硬脂酸转化率的影响。结果表明,合成乙二醇硬脂酸酯优化条件是:n(乙二醇)∶n(硬脂酸)=3.5∶1,催化剂用量为硬脂酸的物质的量的2.8%,带水剂甲苯的用量为硬酯酸质量的30%,反应时间150min,在此条件下,酸的转化率可达97.82%。     

Keggin型P-Mo-V杂多酸催化合成苯甲酸正丁酯

以苯甲酸和正丁醇为原料,甲苯为带水剂,用自制的Keggin型钼钒磷杂多酸为催化剂,合成了苯甲酸正丁酯。探讨了催化剂用量、原料配比、带水剂用量和反应时间对产品收率的影响,并用多种手段对产品做了检测分析。结果表明,合成该酯的最佳工艺条件为:n(正丁醇)/n(苯甲酸)=3,催化剂用量为反应物料总质量的12%,甲苯做带水剂,反应温度控制在110～115℃,反应时间2h。在此条件下,酯收率可达80 49%。     

铁系固体超强酸催化合成乳酸辛酯的研究

以铁系固体超强酸为催化剂 ,研究了催化合成乳酸辛酯的最适宜反应条件。实验表明 :铁系固体超强酸催化剂具有良好的催化活性 ,以环己烷为带水剂 ,在酸醇摩尔比为 n(乳酸 )∶ n(正辛醇 ) =1∶ 1.35的条件下 ,催化剂用量为 0 .80 g· 0 .2 m ol- 1 乳酸 ,反应温度为 14 0℃ ,反应时间 6 0 m in,酯化率达到了 98.6 %。     

活性白土催化合成三甘醇二异辛酸酯

以三甘醇和异辛酸为原料,在活性白土的作用下,催化酯化合成三甘醇二异辛酸酯。考察酸醇物质的量比、反应时间、催化剂用量、带水剂用量等条件对酯化反应的影响,确定最佳合成工艺条件。合成三甘醇二异辛酸酯的最佳条件为酸醇物质的量比为4∶1,反应时间为5h,催化剂用量为8%,带水剂用量为33%,三甘醇转化率可达93.45%。催化剂不经任何处理重复使用3次后,三甘醇转化率有所下降,但催化剂经过再生后,三甘醇转化率可达93.2%,产品经气相色谱分析三甘醇二异辛酸酯含量为77.01%,三甘醇一异辛酸酯含量是14.48%。     

二氧化硅负载硅钨酸催化合成苹果酯

以二氧化硅负载硅钨酸为催化剂,乙酰乙酸乙醇和1,2-丙二醇为原料合成了苹果酯,探讨二氧化硅负载硅钨酸对合成苹果酯反应的催化活性,较系统的研究了原料量比,催化剂用量,带水剂吐用量和反应时间诸因素对产品收率的影响。结果表明,在n(乙酰乙酸乙酯):n(乙二醇)=1:1.4,催化剂用量为反应物料总质量的0.8%,带水剂环己烷10mL,反应时间45min的优化条件下,苹果酯的收率可达66.9%。     

响应面法优化离子液体催化合成乳酸乙酯

以酸性咪唑离子液体为催化剂,乙酸乙酯为带水剂研究了乳酸乙酯的合成。应用响应面法预测醇酸摩尔比、离子液体（IL）酸摩尔比、全回流时间、带水剂用量、分水反应时间5个因素对产率的影响,并通过实验发现实际收率与预测值基本吻合。得到的最佳反应条件为：醇酸摩尔比4,IL酸摩尔比0.7,全回流1.2 h,加入带水剂用量为理论用量的74%,分水反应6.6 h,此时乳酸乙酯的收率可达80%。     

离子液体催化聚乳酸丁醇醇解反应

以离子液体[Bmim][OAc]为反应介质和催化剂, 对聚乳酸 (PLA)丁醇醇解反应进行了研究。考察了反应温度、反应时间、离子液体用量、丁醇(n-butanol)用量对反应结果的影响。得到较佳工艺条件为:反应温度为150℃、反应时间为3 h、m([Bmim][OAc]):m(PLA)=0.2:1、n(n-butanol):n(PLA)=5:1。在上述条件下, PLA醇解反应转化率≥81%, 乳酸正丁酯收率≥70%。采用FT-IR技术对产品的结构进行了表征。 离子液体的回用性能结果表明:[Bmim][OAc]重复利用6次后, PLA转化率和乳酸正丁酯收率无明显变化。     

Pervaporation Reactor for Enhanced Esterification of Lactic Acid and Isobutyl Alcohol

The esterification of lactic acid and isobutyl alcohol to isobutyl lactate and water was intensified. An ex situ pervaporation reactor (PVR) shifted the equilibrium towards the formation of isobutyl lactate. The effects of temperature, molar acid/alcohol ratio, catalyst loading, and ratio of effective membrane area to total reaction volume were investigated with and without a PVR. Lactic acid conversion beyond reaction equilibrium was enhanced with such a reactor. The partial fluxes of the individual components were evaluated for each reaction parameter indicating that the membrane was selective towards separation of water and exhibited a good performance. The performance of the ex situ PVR was studied, which revealed that the water removal rate exceeded the water production rate.     

在离子液体中锡催化多糖分解合成乳酸

淀粉和纤维素能够被四氯化锡催化转化为乳酸甲酯和乳酸,使用离子液体是实现多糖转化的关键。在实验中考察了催化剂、离子液体、反应时间和反应温度对于总乳酸收率的影响。实验结果显示,在1,3-二甲基咪唑硫酸甲酯盐中的淀粉在140℃条件下反应2 h可获得54%总乳酸收率,纤维素的收率为15.1%。果糖在同样的反应条件下收率为95%,葡萄糖为64%,这意味着反应机理可能为纤维素和淀粉首先降解为葡萄糖,然后异构为果糖,最终果糖分解为乳酸。     

脱水法合成乳酸乙酯

以乳酸和乙醇为原料 ,在对甲苯磺酸的催化下以氧化钙或 3A分子筛或MgSO3 为脱水剂 ,采用自制的索氏提取器进行回流脱水合成乳酸乙酯。对影响乳酸乙酯产率的诸因素进行了考察。实验结果表明 :加入脱水剂和带水剂可以显著提高乳酸乙酯的产率 ,酯的产率随催化剂用量的增加、醇酸物质的量比的增大、反应时间的延长先增加到最高点后略有降低。当乳酸 0 1mol、乙醇 0 3mol、对甲苯磺酸 1 0g、带水剂环己烷 5 0mL、脱水剂CaO 18 7g和反应 2h时 ,乳酸乙酯的产率达 84 5 %。     

固体超强酸负载镧催化合成乳酸乙酯

以乳酸和乙醇为原料,在SO42-/La2O3-TiO2的催化下,以氧化钙为脱水剂,采用索氏提取器进行回流脱水合成乳酸乙酯。对影响乳酸乙酯酯化率的诸因素进行了考察。结果表明,加入脱水剂和带水剂可以显著提高乳酸乙酯的产率。适宜反应条件为:SO42-/La2O3-TiO2中La3+浓度为0.07 mol/L,陈化14 h,在450℃下焙烧3 h;醇∶酸(摩尔比)=2∶1,催化剂用量为乳酸质量的2.0%,带水剂苯25 mL/0.1 mol乳酸,反应3 h时,酯化率达84.2%。且该催化剂有良好的重复和再生性。     

Effect of solvent and impurity on synthesis of ethyl lactate from fermentation-derived ammonium lactate

Fermentation-derived ammonium lactate was converted into ethyl lactate by decomposition in various organic solvents followed by esterification with ethanol over Amberlyst catalyst. The ammonium lactate was decomposed more efficiently in an organic solvent with high boiling point, where the produced lactic acid was stabilized well as a monomer without oligomerization. However, only the nonreactive phosphate-type solvent such as triethyl phosphate and tributyl phosphate showed a notable ethyl lactate yield in the subsequent esterification reaction compared with dimethyl sulfoxide and N-methyl pyrolidine. The lactic acid yield in ammonium lactate decomposition and the subsequent ethyl lactate yield were also highly dependent on solvent ratio to ammonium lactate, temperature and pressure in ammonium lactate decomposition reaction. The amino acid impurity contained in the fermented ammonium lactate as well as the unreacted ammonium lactate reduced the acid strength of Amberlyst-36, which resulted in the final ethyl lactate yield.     

Effects of operation variables on the recovery of lactic acid in a batch distillation process with chemical reactions

In this study, the feasibility of recovery of lactic acid by batch reactive distillation using cation exchange resin as a catalyst was investigated. For the recovery of lactic acid, two reactions, esterification and hydrolysis, are involved and hence, an apparatus with two distillation columns was developed and operated in a batch mode to ensure enough residence time in the reboiler and column. The effects of operation variables such as catalyst loading, reactant mole ratio, feed concentration, type of alcohols and partial condenser temperature on the yield were studied. In this study, the reaction products of the esterification (methyl lactate and water) were distilled to the hydrolysis part to be recovered into pure lactic acid. The yield of lactic acid increased as catalyst loading in the esterification part increased and reactant mole ratio and feed lactic acid concentration decreased. Methanol as a reactant gave higher yield than any other alcohols. The yield of recovered lactic acid was as high as 90%. The yield of lactic acid was closely related to the boiling temperature of the reaction mixture in the esterification part     

Application of zeolite T membrane to vapor-permeation-aided esterification of lactic acid with ethanol

Zeolite T membranes were applied to vapor-permeation-aided esterification of lactic acid with ethanol. The hybrid process provided almost complete conversion within a short reaction time by removing water from the reaction mixture. Zeolite T membrane worked steadily for a long time. The reaction time-courses were described by a model based on the assumptions that the esterification obeyed second-order kinetics and the permeation flux of each component was proportional to its concentration in the reaction mixture. The final reaction liquid mixtures consisted mostly of ethyl lactate and ethanol with little ester of polylactic acids, although concentrated lactic acid solution was used as a source.