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the decarboxylation
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  脱羧
     The key step in these syntheses is the decarboxylation Of 16-hydroxy- 9E -hexadecylenic acid ( 2 )by DBU
     关键步骤是16-羟基-9E-十六碳烯酸(2)在DBU作用下的脱羧反应。
短句来源
     Compared with conventional method,in the decarboxylation reaction under microwave irradiation,the reaction time was reduced from 6 h to 6 min and the yield was enhanced from 65% to 97%.
     尤其在脱羧反应中,与常规方法相比,反应时间由6h缩短为6min,收率由65%提高到97%。 总收率由43 4%提高至64 7%。
短句来源
     Study on the Decarboxylation of 2-Keto-gluconic Acid
     2-酮基-D-葡萄糖酸加热脱羧反应的研究
短句来源
     The results show that the decarboxylation percentage of Liaohe rocks is the highest in presence of Na 2SO 4, the following are KCl, NaCl and MgCl 2. The decarboxylation percentage of Jianghan rocks is the highest in presence of KCl, the following are NaCl, Na 2SO 4 and MgCl 2.The difference of decarboxylation percentage is resulted from their rocks with different compositions.
     对于江汉生油岩样 ,KCl作用下的十八烷酸矿物催化脱羧率最高 ,其次为NaCl,Na2 SO4 ,MgCl2 。
短句来源
     The decarboxylation reaction of acrylic acid in ground state has been investigatedby using self-consistent-field molecular orbital method(Semi-empirical AMI andHF/3-21G ab initio methods).
     用自洽场分子轨道法(半经验AM1法及从头算HF/3-21G 法)研究了基态丙烯酸脱羧的反应途径.
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  “the decarboxylation”译为未确定词的双语例句
     A large amount of organic materials in the shale and mudstone in member 1,Qingshankou formation (K_1qn_1) adjacent to the reservoir rocks of Fuyu oil bearing formation in the biochemical reforming stage,especially in the stage of thermocatalytic transformation of organic ma- terials under the decarboxylation and other process were transformed into a lot of CO_2,H_2S and various organic acids.
     与扶余油层储集砂岩邻接的、富含有机质的青1段泥页岩中的大量有机质,在有机质成熟的生物化学改造阶段,尤其在热催化转化阶段,以脱羧作用或其它作用生成大量的 CO_2、H_2S 和各种有机酸。
短句来源
     So under the optimal pH and temperature,K_m of protein CpHBDC on the decarboxylation was 40.1 mmol/L.
     在最适的pH 7.5和30℃的条件下,蛋白质的米氏常数Km为40.1 mm o l/L。
短句来源
     Agmatine in mammalian tissues, which is formed by the decarboxylation of L-Arginine by the enzyme L-arginine decarboxylase(L-ADC), has been postulated to be an endogenous ligand for imidazoline receptors.
     胍丁胺是精氨酸在左旋精氨酸脱羧酶(L-ADC)催化下脱羧基的产物,是咪唑啉受体的内源性配体。
短句来源
     But they grew well in peptone water containing 3 or 6% NaCl. Test for the decarboxylation of lysine and ornithine were negative and argininepositive.
     不能在无盐和含有8%NaCl 的胨水中生长,但在含有3%和6%NaCl的胨水中生长良好。
短句来源
     The carbonates in crystalline MnCO_2 in the Modaoxi Formation are derived mainly from the decarboxylation (D) zone.
     磨刀溪组结晶锰碳酸盐的主要来源是热解脱羧基带(D)。
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  相似匹配句对
     Mechanism and Application of Decarboxylation
     脱羧反应的历程及其应用
短句来源
     Progress in The Study of The Decarboxylation Reaction
     脱羧反应研究进展
短句来源
     Aim:To study the decarboxylation of quinolones.
     目的:研究喹诺酮类化合物脱羧反应。
短句来源
     Triethanolamine was used instead of N,N-dimethylaniline in decarboxylation.
     脱羧反应以三乙醇胺代替剧毒的N,N-二甲基苯胺,并对其后处理进行了改进。
短句来源
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  the decarboxylation
Parameters of the Arrhenius equation for the rate constants of the decomposition of the peroxide and the decarboxylation of acyloxyl radicals are obtained.
      
α-Lipoic acid (ALA) is a naturally occurring enantiomer of lipoic acid and is a cofactor of key metabolic enzyme complexes catalyzing the decarboxylation of α-keto acids.
      
LEC has been used to monitor the decarboxylation of racemic DL-aspartic acid byPseudomonas dacunhae.
      
It entails large-volume injection (LVI) and programmed-temperature vaporization (PTV) of water samples, thermal decarboxylation of TCA to chloroform in the injector, and GC-ECD analysis of the decarboxylation product.
      
The present findings support that one of the effects ofl-deprenyl may be to facilitate the decarboxylation ofl-DOPA by increasing the availability of AADC.
      
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The preparation of 2, 2-dihydroxycyclohexylidene acetic acid lactone (Ⅳ) as a starting material for the syntheses of 3, 4-cis-triene compounds of the vitamin D type has been studied.Only α-carbethoxy-2-hydroxycyclohexen-(2)-ylidene acetic acid lactone [Ⅷ, m. p.110-111°, λ?? 296 mμ (ε18,600)] was obtained by the treatment of the diethyl 2-ketocyclohexyltartronate (Ⅵ) with acetyl chloride. The structure of Ⅷ was substantiated by results from the decarboxylation and the ozonization of its free acid, α-carboxy-2-hydroxycyclohexen-(2)-ylidene...

The preparation of 2, 2-dihydroxycyclohexylidene acetic acid lactone (Ⅳ) as a starting material for the syntheses of 3, 4-cis-triene compounds of the vitamin D type has been studied.Only α-carbethoxy-2-hydroxycyclohexen-(2)-ylidene acetic acid lactone [Ⅷ, m. p.110-111°, λ?? 296 mμ (ε18,600)] was obtained by the treatment of the diethyl 2-ketocyclohexyltartronate (Ⅵ) with acetyl chloride. The structure of Ⅷ was substantiated by results from the decarboxylation and the ozonization of its free acid, α-carboxy-2-hydroxycyclohexen-(2)-ylidene acetic acid lactone [Ⅸ, m. p. 152-153°(decomp.),λ?? 285 mμ(ε 13,600)]. Ⅸ yields 2-hydroxycyclohexen-(2)-ylidene acetic acid lactone [Ⅻ, b. p. 85-86°/0.15 mm, n_D~17 1.5592,λ?? 274 mμ (ε 12,800)] on pyrolysis at 180°, and glutaric acid together with succinic acid on oxidative ozonization.Ⅵ was saponified to give 2-ketocyclohexyltartronic acid (XIII, m. p.144-145°).The reaction of XIII with hydrogen bromide in glacial acetic acid is quite complicated.It yields 2-ketocyclohexene-(6) acetic acid [XV, m. p. 99-100 , λ?? 240 mμ(ε 8,650)], o-hydroxyphenylacetic acid [XVII, m. p, 146-147°, λ?? 275 mμ(ε 2,250), λ?? 238, 291 mμ(ε 9,120, 3,900)], Ⅻ, the lactone of acid XVII (XVI), and other two unknown substances. XII and XVI were obtained as a mixture,the nature of which has been revealed by the analysis of UV-absorption spectra and the preparation of derivatives like N-benzyl-??-hydroxy-phenylacetamide [XVIII, m.p. 111.5-112.5? ?? 275 m?? (?? 1,390)] and ??-hydroxyphenylacetic phenylhydrazide [XIX,m.p. 181.5-182.5? ?? 276 m?? (?? 4,190)].Pyrolysis of XIII at 140?was successful. From the product there were isolated IV [m.p. 85.5-86.5? ?? 217 m?? (?? 9,790), ?? 249 m??(?? 3,730)] and its isomer,trans-2-ketocyclohexylidene acetic acid [XXI, m.p. 120-121.5? ?? 251 m?? (?? 5,650),?? 251 m?? (?? 6,980)]. The structures of IV and XXI were established by UV-spectral analysis, the preparation of some characteristic derivatives and the ozonization deg-radation. In case of IV, its structure has been further confirmed by its conversion into XII.

本文报告2,2-双羟亚环己基乙酸内酯(Ⅳ)的合成作为纯化学法合成维生素丁类型的3,4-顺-共轭三烯化合物的原料. 2-氧代环己基羟基丙二酸二乙酯(Ⅵ)经乙酰氯脱水未得V,而仅得α-乙氧羰基-2-羟基亚环己烯-[2]-基乙酸内酯(Ⅷ).Ⅷ的结构是根据其水解物α-羧基-2-羟基亚环己烯-[2]-基乙酸内酯(Ⅸ)的脱羧与臭氧化结果而证明. Ⅵ经皂化为2-氧化环己基羟基丙二酸(Ⅷ),再以溴化氢的冰醋酸鲍和溶液处理,反应复杂.产生2-氧代环己烯-[6]-基乙酸(XV)、邻羟基苯乙酸(ⅩⅦ)及其内酯(ⅩⅥ)、2-羟基亚环己烯-[2]-基乙酸内酯(Ⅻ)及其他二种产物. Ⅷ经焦化法脱水脱羧终于获得Ⅳ和其反式异构体2-氧代-反-亚环己基乙酸(XXI).Ⅳ与XXI的结构已由其衍生物制备及臭氧降解结果而加以证明.

Norepinephrine, the chemical mediator for the transmission at peripheral adrenergic junctions, is formed by the decarboxylation of dihydroxyphenylalanine (DOPA). It has been reported that amino acids structurally related to DOPA have specific pharmacological properties. In view of the fact that guanethidine (I), a clinically useful hypotensive agent, is an azacyclo compound, it would be interesting to prepare some amino acids carrying cyclic amino substituents. Heptamethyleneimine, hexamethyleneimine,...

Norepinephrine, the chemical mediator for the transmission at peripheral adrenergic junctions, is formed by the decarboxylation of dihydroxyphenylalanine (DOPA). It has been reported that amino acids structurally related to DOPA have specific pharmacological properties. In view of the fact that guanethidine (I), a clinically useful hypotensive agent, is an azacyclo compound, it would be interesting to prepare some amino acids carrying cyclic amino substituents. Heptamethyleneimine, hexamethyleneimine, and piperidine were reacted respectively with formaldehyde and diethyl formamido-malonate, giving the corresponding α-(Nazacycloalkyl)-formamidomalonic esters (Ⅳ). The latter afforded α-amino-β-(N-azacydoalkyl)-propionic acids (Ⅲ) on acid hydrolysis. Ethyl ?-(N-azarycZoalkyl)-propionates and acetates (Ⅴ) were formed on condensation of heptamethyleneimine, hexamethyleneimine, or piperidine with ethyl chloroacetate or ethyl α-chloropropionate. Hydrolysis of these esters with hydrochloric acid gave the corresponding hydrochlorides of α-(N-azarycZoalkyl)-propionic acids or acetic acids (Ⅱ). In view of the high biological activities of hydrazides, the esters (Ⅴ) were subjected to hydrazinolysis with phenylethyl hydrazine, benzyl hydrazine, or hydrazine hydrate, forming numerous hydrazides (Ⅵ). Pharmacological tests revealed that compounds Ⅵ_k and VIn had hypotensive activity, and compound Ⅵm dilated coronary vessels without exerting marked influence on heart rate and contractile force of the heart.

氮八环、氮七环、氮六环与甲醛及甲酰氨基丙二酸二乙酯缩合,生成相应的α-(N-氮杂环甲基)甲酰氨基丙二酸二乙酯(Ⅳ),再用盐酸水解后得α-氨基-β-(N-氮杂环基)丙酸(Ⅲ).氮八环、氮七环、氮六环与氯乙酸乙酯及α-氯丙酸乙酯缩合,生成相应的α-(N-氮杂环基)丙酸乙酯及乙酸乙酯(Ⅴ),然后用盐酸水解,制得α-(N-氮杂环基)取代的丙酸及乙酸(Ⅱ)的盐酸盐.V分别和水合肼、苯甲肼或苯乙肼在封管中加热缩合,制成相应的酰肼(Ⅵ).其中某些化合物具有降压及冠脉扩张作用.

We have investigated the decomposition of lauroyl peroxide, 1 in benzene at 30℃, 40℃ and 50℃ and followed the reaction iodometrically. With an initial concentration of 1 between 0.1 to 0.2M and at temperature of 30℃ or 40℃, a first-order plot could be obtained, but the slope increased with the increase of initial concentration (Fig. 1) indicating that some induced decomposition was involved. When the decomposition was carried out at 50℃, a first-order plot could be obtained only when the initial concentration...

We have investigated the decomposition of lauroyl peroxide, 1 in benzene at 30℃, 40℃ and 50℃ and followed the reaction iodometrically. With an initial concentration of 1 between 0.1 to 0.2M and at temperature of 30℃ or 40℃, a first-order plot could be obtained, but the slope increased with the increase of initial concentration (Fig. 1) indicating that some induced decomposition was involved. When the decomposition was carried out at 50℃, a first-order plot could be obtained only when the initial concentration was below 0.04 M, but deviation became apparent with higher initial concentrations (Fig. 1, 2). A kinetic analysis of the data from the experiment at 50℃ gave the results which fit well with a first plus three halves order kinetics (Fig. 3). The first-order rate constant k_1 for spontaneous decomposition was found to be 0.0115 hr~(-1), and the rate constant k_1 for induced decomposition 0.014 mol~(-1/2)·1~(1/2).hr~(-1).-dα/dt=k_1+k_ia~(3/2) (1)When 1 was decomposed in benzene to which the radical scavenger "galvinoxyl" 2 was added, and the progress of reaction monitored by optical density measurements at 434 nm as described by Williams et al, the results showed a first-order reaction with respect to 1 and a zero-order reaction with respect to 2 (Fig. 4). It can be seen from Figure 4 that the straight lines are all nearly parallel with about equal slope, irrespective of the molar ratio between 1 and 2 being changed from 7 to 207, a thirty-fold variation. This means that, in the presence of 2, the induced decomposition was suppressed.From the above results, on the assumption that two radicals were produced from the decomposition of one molcoulo of 1 and that these radicals could be scavenged entirely by 2, the first-order rate constant k_1 was calculated to be 0.0057 hr~(-1), which was just about half the value as determined from iodometric measurements as given above. This implies that only one half of the radicals produced from the decomposition of 1 was scavenged by 2.The carbon dioxide evolved from the decomposition of 1 in benzene in the absence of 2 amounted to about 87% of the theoretical value. But when 2 was added to the reaction mixture, the amount of carbon dioxide dropped to about 50%.The above results could be interpreted by the following mechanism. In accordance with the general view, the decomposition of 1 proceeded by the fission of O—O bond, followed by the decarboxylation of the resulting RCOO· radicals, producing R· and CO_2.(RCOO)→2RCOO·→2R·+2CO_2 (2) When the decomposition was conducted at 50℃ in the presence of 2, only about one half of the RCOO· radicals decarboxylated and the resulting radicals partly reacted within the cage (c), through disproportionation, recombination etc., and partly diffused into solution to become "free" radicals (d). Thus the free radicals, which were scavenged by 2, would consist at least part of the RCOO· radicals formed. These sequences may be formulated as follows:However, a more tempting and also more tentative interpretation could be put forward as an alternative. Thus when 1 was decomposed in benzene at 50℃, a simultaneous breakage of O—O bond and R—COO linkage took place with the formation of R., CO_2 and RCOO· in one step. Again about one half of the radicals reacted within the cage and the remaining half diffused into solution with the same results. This mechanism may be depicted by the following scheme: However, our results are different from Ward's. Ward et al. studied the decomposition of 1 in o-dichlorobenzene at 112℃ with 2-iodopropane as the scavenging agent and found that no net polarization was observed in the CIDNP spectra for the products. They conclude that the decarboxylation of C_(11)H_(23)COO· must be a very fast process with a life<10~(-10) sec. and cannot be scavenged.Since the experiments by Ward et al. was conducted at 112℃, the extensive decarboxylation of the RCOO· was not surprising. We did the decomposition experiment at 50℃ and it might be that, in the presence of 2, only about one half of the RCOO· radicals decarbexylated under these conditions. The fact that approximately 50% of the theoretical amount of carbon dioxide liberated supported this contention.In order to ascertain whether the decomposition of 1 undergoes by a stepwise sequence or it may proceed by a concerted mechanism involving the simultaneous breaking of O—O and R—COO bonds, a detailed study of the decomposition products is necessary. Work along this line is being planned.Finally, it should be mentioned that Bawn and Halford have reported early a kinetic study of the decomposition of 1 with DPPH as the scavenging agent. On the assumption that 1 decomposed into two RCOO· radicals and DPPH could capture these radicals with a 100% efficiency, these authors obtained a value of 0.0078 hr~(-1) for k_1 at 50℃, which is lower than what we have found (0.0115 hr~(-1)) from iodometric determination and somewhat higher than the value (0:0057 hr~(-1)) which we have found by scavenging experiments. In view of the report by Shine et al. that DPPH could cause an induced decomposition of acyl peroxide, it appears that the value reported by Bawn et al. may be a little uncertain.

进行了过氧化月桂酰(1)在脱氧的苯中的分解动力学研究,当起始浓度0.1~0.2克分子·升~(-1),温度30℃、40℃时,1不是严格地按一级反应分解的。在50℃下起始浓度0.04~0.34克分子·升~(-1)时,实验结果符合一级加二分之三级的反应规律:-(da/dt)=k_1a+k_1a~(3/2)。求出的自发分解速率常数k_1=0.0115小时~(-1),诱导分解速率常数k_1=0.014克分子~(-1.2)·升~(1/2)·小时~(-1)。研究了50℃时有自由基捕获剂galvinoxyl(2)的动力学试验,根据光密度变化测定分解反应,知1为一级,2为零级,诱导分解受到抑制。假定1的初级分解生成两个自由基,且可被2完全捕获,则计算出来的分解速率常数为0.00570小时~(-1),恰好为碘量法测定1的自发分解速率常数的一半;同时,根据有2存在下测出1分解产生的二氧化碳量,约为理论值(假定一个1分子分解产生两个二氧化碳分子)的一半的事实,推论1在50℃的苯中的初级分解可能有如下两种过程: (RCOO)_2→2RCOO·→R··OCOR+CO_2 或者(RCOO)_2→R·CO_2·OCOR→R··OCOR+CO...

进行了过氧化月桂酰(1)在脱氧的苯中的分解动力学研究,当起始浓度0.1~0.2克分子·升~(-1),温度30℃、40℃时,1不是严格地按一级反应分解的。在50℃下起始浓度0.04~0.34克分子·升~(-1)时,实验结果符合一级加二分之三级的反应规律:-(da/dt)=k_1a+k_1a~(3/2)。求出的自发分解速率常数k_1=0.0115小时~(-1),诱导分解速率常数k_1=0.014克分子~(-1.2)·升~(1/2)·小时~(-1)。研究了50℃时有自由基捕获剂galvinoxyl(2)的动力学试验,根据光密度变化测定分解反应,知1为一级,2为零级,诱导分解受到抑制。假定1的初级分解生成两个自由基,且可被2完全捕获,则计算出来的分解速率常数为0.00570小时~(-1),恰好为碘量法测定1的自发分解速率常数的一半;同时,根据有2存在下测出1分解产生的二氧化碳量,约为理论值(假定一个1分子分解产生两个二氧化碳分子)的一半的事实,推论1在50℃的苯中的初级分解可能有如下两种过程: (RCOO)_2→2RCOO·→R··OCOR+CO_2 或者(RCOO)_2→R·CO_2·OCOR→R··OCOR+CO_2生成的R·和RCOO·一部分在笼内反应(歧化、再结合等);一部分扩散到溶剂中,当有2存在时,为2所捕获。

 
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