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1.
采用甲醇钠催化异丁醛与草酸二乙酯反应,一釜法合成了3-甲基-2-氧代丁酸钠。在反应料比单因素研究基础上,通过正交实验优化确定了最佳合成工艺条件,即:n(甲醇钠)∶n(异丁醛)∶n(氢氧化钠)∶n(甲醇)∶n(草酸二乙酯)=1.4∶1.4∶1.2∶7.5∶1,合成收率为75%。产品经熔点测定,IR、1H NMR1、3C NMR及元素分析,确认为预想结构,经HPLC分析确定纯度≥98%。 相似文献
2.
针对目前工业上回收3,3-二甲基-4-戊烯酸-3′-甲基-2′-丁烯酯(MBDP)工艺复杂、异戊烯大量分解问题,研究了MBDP直接返回循环使用工艺,MBDP与甲醇、原乙酸三甲酯或与甲醇原乙酸三甲酯混合溶液进行酯交换反应的回收新工艺,比较了四异丙基钛酸酯、甲醇钠、氢氧化钾用作酯交换催化剂的效果,筛选出回收MBDP“一锅煮”最佳工艺:按照n(MBDP):n(原乙酸三甲酯):n(甲醇):n(甲醇钠)=1.0:9.8:9.2:0.05物质的量比投料,74℃-78℃反应2lh,MBDP转化为贲亭酸甲酯和异戊烯醇,单程转化率87.7%,用85%的磷酸中和甲醇钠,蒸出甲醇,直接用于合成贲亭酸甲酯。 相似文献
3.
以氨基磺酸为催化剂,对以异丁醛和1,2-丙二醇为原料合成异丁醛1,2-丙二醇缩醛进行了研究。较系统地研究了醛醇摩尔比,催化剂用量,反应时间,带水剂诸因素对收率的影响,结果表明:氨基磺酸是合成异丁醛1,2-丙二醇缩醛的良好催化剂,最佳反应条件为:异丁醛为0.2-ml,n(异丁醛):n(1,2-丙二醇)=1:1.5,催化剂用量为反应物总质量的6.8%,带水剂环己烷15ml,反应时间60min。上述条件下,异丁醛1,2-丙二醇缩醛的收率可达71.15%。 相似文献
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以氟乙酸甲酯为原料,在甲醇钠催化下与甲酸乙酯缩合得氟代甲酰乙酸酯烯醇式钠盐(化合物Ⅱ),化合物Ⅱ与O-甲基异脲硫酸盐环合得2-甲氧基-5-氟尿嘧啶(化合物V),V在稀盐酸中水解为5-氟尿嘧啶。在n(氟乙酸甲酯):n(钠):n(甲酸乙酯):n(O-甲基异脲硫酸盐);1.0:3.0:2.5:1.0、缩合温度为35℃、缩合时间为2h、环合温度为40℃、环合时间为6h以及水解温度为60℃的最佳反应条件下,目标化合物总收率为45.3%、纯度大于95%,其结构经IR、1^HNMR确证。 相似文献
6.
以固体超强酸SO4^2-/TiO2-WO3为催化剂,对以异丁醛和乙二醇为原料合成异丁醛乙二醇缩醛的反应条件进行了研究。实验表明:SO4^2-/TiO2-WO3是合成异丁醛乙二醇缩醛的良好催化剂,较系统地研究了醛醇物质量比、催化剂用量、反应时间诸因素对收率的影响。最佳反应条件为:n(异丁醛):n(乙二醇)=1.0:1.6,催化剂用量为反应物料总质量的1.0%,环己烷为带水剂,反应时间为75min。上述条件下,异丁醛乙二醇缩醛的收率可达63.8%。 相似文献
7.
自制了硅钨钼酸(H4SiW6Mo6O40)/PAn(聚苯胺)催化剂。通过丁醛和1,2-丙二醇为原料合成丁醛1,2-丙二醇缩醛,探讨了H4SiW6Mo6O40/PAn催化剂对缩醛反应的催化活性,较系统地研究了原料量比,催化剂用量,反应时间诸因素对产品收率的影响。实验表明:H4SiW6Mo6O40/PAn是合成丁醛1,2-丙二醇缩醛的良好催化剂,在n(丁醛):n(1,2.丙二醇)=1:1.7,催化剂用量为反应物料总质量的1.0%,环己烷为带水剂,反应时间40min的优化条件下,丁醛1,2-丙二醇缩醛的收率可达78.5% 相似文献
8.
以甲醛、异丁醛和季戊四醇为主要原料,在催化剂作用下利用循环一锅法合成螺二醇。通过正交优化实验,考察了物料配比、温度、反应时间、溶剂量以及催化剂对两步法合成螺二醇收率的影响,确定了合成螺二醇最佳工艺条件,在该适宜条件下,开发了循环-锅法的制备工艺,即n(甲醛):n(异丁醛):n(季戊四醇)=2.85:2.85:1,反应温度75℃,反应时间9h,产品总收率和纯度可达95.4%和99.9%。采用。HNMR和HPLC确定了螺二醇产品结构和纯度。 相似文献
9.
以固载杂多酸盐TiSiW12O40/TiO2为多相催化剂,对以异丁醛和1,2-丙二醇为原料合成异丁醛1,2-N2醇缩醛的反应条件进行了研究。实验表明:TiSiWl2O40/TiO2是合成异丁醛1,2-N2醇缩醛的良好催化剂,较系统地研究了醛醇摩尔比、催化剂用量、反应时间诸因素对收率的影响。最佳反应条件为:n(异丁醛):n(1,2-丙二醇)=1:1.5,催化剂用量为反应物料总质量的0.5%,环己烷为带水剂,反应时间1.0h。上述条件下,异丁醛1,2-丙二醇缩醛的收率可达80.2%. 相似文献
10.
在Na2HPO4-NaH2PO4缓冲溶液中以甲醛和丁醛为原料,经羟醛缩合及氧化反应合成了2,、2-二羟甲基丁酸(DMBA)。羟醛缩合反应的最佳工艺条件为:在Na2HPO4-NaH2PO4缓冲溶液中调pH约为11,反应温度为30℃,n甲醛:n丁醛=2.2:1,反应时间为2.5h;2,2-二羟甲基丁醛氧化反应的最佳工艺条件为:nH2O2:n丁醛=1.1:1,溶液的pH约为4,反应温度为70℃,反应时间为2h。反应产物的结构用红外光谱(IR)表征。 相似文献
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在甲醇钠碱性条件下,以芦竹碱和N-乙酰氨基丙二酸二乙酯为原料进行缩合反应,缩合产物在4%的氢氧化钠水溶液中选择性水解脱羧得到N-乙酰-DL-色氨酸,然后在10%氢氧化钠水溶液中水解得到DL-色氨酸。DL-色氨酸用D-酒石酸拆分,并在苯甲醛催化下实现不对称转化,得到D-色氨酸D-酒石酸盐,最后用三乙胺中和得到目标产物D-色氨酸。确定了缩合和拆分步骤的适宜工艺条件。缩合步骤:甲醇钠摩尔量为芦竹碱的20%,n(芦竹碱)∶(N-乙酰氨基丙二酸二乙酯)=1∶1.2;拆分步骤:乙酸为溶剂,70℃反应,苯甲醛摩尔量为DL-色氨酸的10%,n(DL-色氨酸)∶n(D-酒石酸)=1∶2。 相似文献
13.
以工业异丁醛和氢氧化钠为原料合成了 2 ,2 ,4 三甲基 1,3 戊二醇。优化的工业生产条件为 :异丁酸∶2 5 %氢氧化钠溶液∶5 0 %氢氧化钠溶液 =4 0∶1∶14 (mol) ,第一阶段反应温度 2 8~ 5 2℃ ,时间 1~ 2h ,第二阶段反应温度 90~ 14 0 ,时间 6~ 8h ;合成产品对总原料的收率 >6 0 % ,质量分数≥ 97% ;同时提出了提高产品质量的后处理方法。 相似文献
14.
The base-catalyzed transmethylation of soybean oil has been studied under conditions whereby the reaction starts as a single
phase, but later becomes two phases as glycerol separates. Methanol/oil molar ratios of 6∶1 were used at 23°C. The catalysts
were sodium hydroxide (0.5, 1.0, and 2.0 wt%), potassium hydroxide (1.0 and 1.4 wt%), and sodium methoxide (0.5, 1.0, and
1.35 wt%), all concentrations being with respect to the oil. Oxolane (tetrahydrofuran) was used to form a single reaction
phase. The reactions deviated from homogeneous kinetics as glycerol separated, taking with it most of the catalyst. When 1.0
wt% sodium hydroxide was used, the methyl ester content reached 97.5 wt% after 4 h, compared with 85–90 wt% in the two-phase
reaction. Sodium hydroxide (1.0 wt%), sodium methoxide (1.35 wt%), and potassium hydroxide (1.4 wt%) gave similar results,
presumably because the same number of moles was used. The ASTM biodiesel specification for chemically bound glycerol was achieved
after only 3 min when 2.0 wt% sodium hydroxide was used. However, the standard was not achieved after 4 h when 1.0 wt% sodium
hydroxide was used, the MG content being 1.1–1.6 wt%. The use of 2.0 wt% catalyst is commercially impractical. 相似文献
15.
Hwee Yoong Felicia Gok Jianhneg Shen Shahram Emami Martin J. T. Reaney 《Journal of the American Oil Chemists' Society》2013,90(2):291-298
A metal methoxide is more expensive than a metal hydroxide and dissolves in methanol releasing a methoxide ion without producing water. The methoxide ion has a higher reaction rate making it more preferred for industrial biodiesel production. This study describes the preparation of alkoxide catalysts from metal hydroxides and non-volatile, non-toxic polyols. Heating aqueous solutions of metal hydroxides and different polyols (1,2-propanediol, 1,3-propanediol, glycerol, xylitol and sorbitol) under vacuum yielded polyol-derived alkoxide base catalysts (PDABC). Comparison of the drying process for respective sodium hydroxide-polyol combinations at two mole ratios of sodium hydroxide to polyol showed that drying at 2:1 mole ratio (metal hydroxide to polyol) was more efficient than that of 3:1. Dehydration of alkaline solutions containing three or more hydroxyl groups (glycerol, sorbitol and xylitol) was faster than drying similar solutions of diols. The empirical formula determined confirmed that the resulting powders contained mono-sodium substituted alkoxides at 1:1, 2:1 and 3:1 (sodium hydroxide: polyol) mole ratio. Fatty acid methyl esters were prepared from canola oil and methanol using glycerol sodium alkylate as a catalyst. The conversion yield of oil to methyl ester was greater than 99 %. 相似文献
16.
Hwee Yoong Felicia Gok Shahram Emami Jianhneg Shen Martin J. T. Reaney 《Journal of the American Oil Chemists' Society》2013,90(2):299-305
Biodiesel, fatty acid methyl ester (FAME), was produced by transesterification of canola oil with methanol in the presence of a series of alkoxide/hydroxide base catalysts produced from glycerol, 1,2-propanediol, 1,3-propanediol, xylitol, or sorbitol produced by dehydration reaction of sodium hydroxide in the presence of polyols. Transesterification reactions proceeded efficiently in the presence of sodium alkoxide catalysts prepared at three different mole ratios of sodium hydroxide to glycerol (1:1, 2:1, and 3:1). The production of methyl ester during the course of the reaction was determined repeatedly and the reaction progress was compared with that achieved in a reaction catalyzed by freshly prepared anhydrous sodium methoxide as a standard catalyst. Sodium alkoxide/hydroxide catalysts activity during the first 2 min of the reaction was in the order of: sorbitol < xylitol < sodium methoxide < 1,2-propanediol < 1,3-propanediol < glycerol regardless of the mole ratio of sodium hydroxide to glycerol. All catalysts showed a higher methyl ester accumulation at higher ratios of sodium hydroxide to polyol and had the following order 1:1 < 2:1 < 3:1 (sodium hydroxide:glycerol). Several of these catalysts were as powerful as sodium methoxide in catalyzing the transesterification reaction at the same mole concentration. All alkoxide/hydroxide catalysts resulted in a high FAME accumulation (>95 wt%) in a single transesterification batch reaction. 相似文献
17.
Ertan Alptekin 《Fuel》2011,90(8):2630-2638
In this study, low cost feedstock chicken fat was used to produce methyl ester. After reducing the free fatty acid level of the chicken fat less than 1%, the transesterification reaction was completed with alkaline catalyst. Potassium hydroxide, sodium hydroxide, potassium methoxide and sodium methoxide were used as catalyst and methanol was used as alcohol for transesterification reactions. The effects of catalyst type, reaction temperature and reaction time on the fuel properties of methyl esters were investigated. The produced chicken fat methyl esters were characterized by determining their viscosity, density, pour point, flash point, acid value, methanol content, heat of combustion value, total-free glycerin, mono-di-tri glycerides, copper strip corrosion and ester yield values. The measured fuel properties of the chicken fat methyl ester met EN 14214 and ASTM D6751 biodiesel specifications when using potassium hydroxide and sodium hydroxide catalysts with high ester yield. 相似文献
18.
以异丙醇、氢氧化钠、二硫化碳为原料,合成了液体异丙基黄原酸钠。通过考察物料配比、反应时间、反应温度和NaOH浓度对产品收率的影响,得出适宜的工艺条件为:n(二硫化碳)∶n(氢氧化钠)∶n(异丙醇)=1∶1∶1,反应时间2.5 h,反应温度30℃,氢氧化钠浓度为40%。在此条件下,异丙基黄原酸钠的产率最高可达92.2%。 相似文献
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嘧啶合成新工艺研究 总被引:1,自引:0,他引:1
研究了重要的医药中间体嘧啶的合成工艺,以尿素和丙二酸二乙酯为原料,在甲醇钠催化下合成巴比妥酸,并用三氯氧磷在N,N-二甲基苯胺催化下加氯成2,4,6-三氯嘧啶,将2,4,6-三氯嘧啶以钯碳催化,加氢脱氯得到嘧啶。得出每一步的最佳工艺条件,巴比妥酸合成:配料摩尔比1∶1.1∶1.2(丙二酸二乙酯∶尿素∶甲醇钠),回流,2 h;2,4,6-三氯嘧啶合成:配料摩尔比5∶1(三氯氧磷∶巴比妥酸),100~105°C,2 h;嘧啶合成:配料摩尔比5∶1(氧化镁∶2,4,6-三氯嘧啶),溶剂体积比3∶1(水∶乙醇),0.1 MPa,14 h,60°C。 相似文献