查询词典 acetoacetate

Could keep above 95% in the fixed beds. In order to achieve high stereo-selectivity with yeast, ethyl acetoacetate was used as the model substrate,and a novel approach was proposed to selectively inhibit R-enzymes in yeast before reaction.

以乙酰乙酸乙酯为模型底物，以丙烯酸、乙醚、二甲基亚砜、丙烯酰胺、正己烷等有机溶剂选择性地抑制酵母中R型酶，提高反应立体选择性。

For the α-arylation of ethyl acetoacetate, the product was α-aryl ethyl acetoacetates, rather than ethyl α-arylacetates which are the major products in other catalytic systems.

较为惰性的氯代芳烃在Pd2/L1的催化下，也能够跟1，3-二羰基化合物发生α-芳基化反应。

Bromo-5-formyl -3-methylpyrrole is an important intermediate of tolyporohin. On the base of introducing the present research and development of tolypo- rohin and pyrroles ramification at home and abroad, an emphasis was made on synthesis of 2-Bromo-5-formyl -3-methylpyrrole and the technical conditions of all steps, which was described as follows. Diethyl 3,5-dimethylpyrrole-2,4-dicarboxylate was made by nitrification, reduction and cycle of ethyl acetoacetate.

由于2-溴-5-甲酰基-3-甲基吡咯是合成托尼卟吩的重要中间体，本文在阐述了当前托尼卟吩及吡咯衍生物的国内外研究和开发的基础上，重点研究了2-溴-5-甲酰基-3-甲基吡咯的合成，并对各步反应进行了工艺研究，具体合成步骤如下：本文通过对乙酰乙酸乙酯的亚硝化、还原、成环，反应生成吡咯单环衍生物2，4-二乙氧羰基-3，5-二甲基吡咯。

7-Hydroxy-4-methylcoumarin was synthesized from ethyl acetoacetate and m-dihydroxybenzene by the Pechmann condensation using phenyl sulfonic acid as catalyst under solvent-free conditions.

摘 要：以苯磺酸作催化剂，乙酰乙酸乙酯和间苯二酚为原料，通过Pechmann缩合反应合成7-羟基-4-甲基香豆素。

Synthesis 3,5-dihydroxytoluene by ethyl acetoacetate and diketene as material(yield 6%),by 3-methyl-4-chlorophenol and KOH as material(yield 30-40%)respectively,It was solved for product separation and purify.

分别以乙酰乙酸乙酯与双乙烯酮为原料(收率6%)、3-甲基-4-氯苯酚与氢氧化钾为原料(收率30-40%)合成了3，5-二羟基甲苯，解决了产品分离纯化问题。3-甲基-4-氯苯酚路线进行了中试，中试收率为20%。

Base played a crucial role in this reaction: in the Pd2/L1 catalyzed α-arylation of ethyl malonate, K3PO4 is the base of choice; in the α-arylation of ethyl acetoacetate, K2CO3 is the most effective base.

在这类催化反应中，碱的选择具有重要的影响：以K3PO4为碱， Pd2/L1催化体系在丙二酸二乙酯的α-芳基化中，富电子溴代芳烃显示较好的活性； Pd2/L1催化的乙酰乙酸乙酯α-芳基化时，以 K2CO3为碱，催化体系显示较好的活性，这个催化体系可控制反应得到α-芳基乙酰乙酸乙酯，而不是脱乙酰基的产物。

Methyl-l, 3-oxazine-2,4-dione are prepared from ethyl acetoacetate and ethyl carbamate at 140 for 6h, catalysted by zinc acetate, giving to 48.8% yields which is 33% more than the literature value.

选用醋酸锌作催化剂，使乙酰乙酸乙酯与氨基甲酸酯在140℃反应6h，合成6-甲基-1，3-噁嗪-2，4-二酮，产率达48.8％，较文献报道值高出了33％。

Dihydropyrimidin-2 (1H)-ones were synthesized by condensation of aromatic or aliphatic aldehydes, urea and ethyl acetoacetate or acetylacetone one-pot three-component Biginelli condensation in the presence of room temperature ionic liquids as catalysts under solvent-free conditions.

5利用室温离子液体作催化剂，芳香或脂肪醛、尿素和乙酰乙酸乙酯或乙酰丙酮三组分缩合制备3，4-二氢嘧啶-2-酮衍生物。

For the asymmetric reduction ofα-hydroxyacetophenone and ethyl 4-chloro acetoacetate,-1-phenyl-1,2-ethanediol and-ethyl 4-chloro-3-hydroxybutanoate were produced by the purified enzyme, with the 99% and 94.3% e.e. value respectively.

在纯酶水平验证了近平滑假丝酵母(Candida parapsilosis CCTCCM203011)对外消旋苯基乙二醇的拆分机理，整个去消旋过程是由-苯基乙二醇次级醇脱氢酶和羰基还原酶共同催化完成的。

Base played a crucial role in this reaction: in the Pd2/L1 catalyzed α-arylation of ethy malonate, K3PO4 is the base of choice; in the α-arylation of ethyl acetoacetate, K2CO3 is the most effectiv base.

在这类催化反应中，碱的选择具有重要的影响：以K3PO4为碱，Pd2/L1催化体系在丙二酸二乙酯的α-芳基化中，富电子溴代芳烃显示较好的活性；Pd2/L1催化的乙酰乙酸乙酯α-芳基化时，以K2CO3为碱，催化体系显示较好的活性，这个催化体系可控制反应得到α-芳基乙酰乙酸乙酯，而不是脱乙酰基的产物。

However, as the name（read－only memory）implies, CD disks cannot be written onorchanged in any way.

然而，正如其名字所指出的那样，CD盘不能写，也不能用任何方式改变其内容。

Galvanizes steel pallet is mainly export which suits standard packing of European Union, the North America. galvanizes steel pallet is suitable to heavy rack. Pallet surface can design plate type, corrugated and the gap form, satisfies the different requirements.

镀锌钢托盘多用于出口，替代木托盘，免薰蒸，符合欧盟、北美各国对出口货物包装材料的法令要求；喷涂钢托盘适用于重载上货架之用，托盘表面根据需要制作成平板状、波纹状及间隔形式，满足不同的使用要求。