esterification reaction the synthesis of aspirin

... ENANTIOSELECTIVE MANNICH REACTION: TOWARDS THE SYNTHESIS OF -AMINO ACIDS PAN YUANHANG (BSc., Zhejiang University) A THESIS SUBMITTED FOR THE DEGREE OF DOCTOR OF PHILOSOPHY DEPARTMENT OF CHEMISTRY NATIONAL ... Mannich reaction of phenylacetate thioesters by soft enolization Scheme 2.3 Cross-aldol reaction of isatins and ketones Scheme 2.4 Synthesis of MAHTs started from diethyl malonate Scheme 2.5 Synthesis ... use of these reactions Examples with high level of enantiomeric inductions are still rare and the substrate scopes of many reactions are still limited The organocatalytic version of this reaction...

Ngày tải lên: 10/09/2015, 08:31

... during the intracellular growth of the pathogen in its host This could explain the absence of the l-gulono1,4-lactone dehydrogenase reaction product in the M tuberculosis cells grown in vitro The ... (ALO1), which catalyzes the last step in the biosynthesis of erythroascorbic acid in yeasts, resulted in attenuated virulence of the Candida albicans mutant [42] If synthesized by the Rv1771 l-gulono1,4-lactone ... oxidoreductases In order to determine the enzymatic activity of the GST-tagged Rv1771 protein of M tuberculosis, the oxidase activity was tested in the presence of the l-gulono-1,4-lactone and l-galactono-1,4-lactone...

Ngày tải lên: 07/03/2014, 12:20

... content of 48.0% [43] The GC content of the region essential for the biosynthesis of SPA in the other serotype strains (b–e) of A actinomycetemcomitans is also lower than the average GC content of these ... [20] The GC contents of the genes essential for SPA biosynthesis in A actinomycetemcomitans SUNYaB 75 are lower than the average GC content (47.8%) of the genes flanking them The GC contents of ... that of authentic NADP+ The reason why the NADP+ peak appeared in the gmd gene product reaction has been unidentified The retention time of the putative GDP-6-deoxy-D-talose was 36.0 in the reaction...

Ngày tải lên: 17/03/2014, 10:20

... However, all these reported methods either produced solid nanorods, nanowires or hollow nanotubes but without pores on the wall To the best of our knowledge, very few reports on the synthesis of porous ... After adding the NaOH solution into the reaction mixture a brownish black-colored reaction mixture appears instantaneously The next step for the hydrothermal treatment, 2.5 mL of the brownish ... removal of the template by solvent extraction and calcinations, the FE-SEM micrograph (Fig 2B) reveals the remarkable effect on the macroscopic structure of the nanorods The presence of nanorods...

Ngày tải lên: 19/03/2014, 16:48

... in the solvothermal reactions The selection of the solvent plays a key-role through the control of the chemical mechanisms leading to the targetmaterial The reaction mechanisms induce, during the ... Oxido-reducing reactions are involved during the solvothermal process: Hg2+?2Hg2+ + 2e– and Te + 2 e–?Te2– Then the reaction, with the precursor Rb2Te, leads to the synthesis of Rb2Hg3Te4 The use of FeCl2 ... corresponding solvothermal reactions Chemical parameters Two different parameters can be taken into account: the nature of the reagents and the nature of the solvent The chemical composition of the precursors...

Ngày tải lên: 20/03/2014, 13:08

... XRD by the Scherrer equation, are presented in Table 4.1 Reaction mechanisms of metal oxide particles in non-aqueous synthesis This section will discuss the organic side of the synthesis of inorganic ... oven The precursors and the solvents were identical to those in the sonochemistry reaction The microwave and sonochemical results of the BET surface area and the crystallite size of all the materials, ... but liquid reaction media The organic components and the organic reaction pathways play a fundamental role in the non-aqueous synthesis of the inorganic products In this process, the formal oxygen...

Ngày tải lên: 20/03/2014, 13:11

... volume of 20 lL The reaction was initiated by the addition the enzyme (100 ng reaction) 1 for the determination of NTP synthesis rates and 0.5–1 ng reaction) 1 for the determination of NDP synthesis ... levels for DNA synthesis could be the reason Mollicutes lack the de novo synthesis of purine and pyrimidine bases and have to rely on salvage path1988 ways for the biosynthesis of nucleotides ... rates of [3H]ADP synthesis, although the highest [3H]ADP synthesis rate was obtained when ATP was the phosphate donor (Table 1) 1986 In the reactions described above, the concentration of phosphate...

Ngày tải lên: 30/03/2014, 08:20

... through the diffusion of F− ions and simultaneous effusion of the [TiF6 ]2− ions The faster rate of formation of TiO2 nanotubes using ultrasonic waves can be explained by the faster mobility of the ... into the nanotubular reaction channel and effusion of the [TiF6 ]2− ions from the channel It is well known that the cavitation effect of ultrasonication results in implosion of bubbles near the ... magnetic stirring The saturation of current with time indicates the development of repassivation, the saturation of nanotube formation These results are in line with the findings of our FESEM studies...

Ngày tải lên: 05/05/2014, 15:26

... These substances also control both towards the toxicants makes them the potential the reduction rate of metal ions and the materials for the decomposition applications agglomeration process of ... remediation the reactions are analogous to their solution agent, adsorbent, etc [33-36] In the present behavior Recent investigations have explored work, the synthesis of CaO nanoparticles by the promising ... reaction of the 2-CEPS with CaO program for GC: The carrier gas was helium nanoparticles with a flow rate of mL.min-1 The initial and For this purpose, 10 μL of 2-CEPS, mL of final temperature of the...

Ngày tải lên: 06/05/2014, 08:55

... investigated Herein, we report the further use of this facile, low-cost, green solgel-based hydrothermal method and an investigation of the dependence of the morphology evolution of the self-assembled flower-like ... concentration of OH is present in the aqueous medium Following the decrease in the concentration of Zn(OH)42 due to the initial fast nucleation of ZnO, the absorption of OH ions on the positively ... used in the reaction system as the solvent medium 2.2 Synthesis of 3D flower-like ZnO microstructures composed of nanosheets In this work, 3D flower-like ZnO samples were synthesized by the following...

Ngày tải lên: 06/05/2014, 13:26

... furnish the pure oxime in 60-98% yield 90 Page of run might be due to the loss of active sites of the catalyst Conclusions To the best of our knowledge, Bi O has never been used in the synthesis of ... Bi2O3 loading appreciably decreased the rate and yield of the reaction We have also checked the reusability of the catalyst using the recovered Bi O from the reaction It is observed that recovered ... in a mortar with a pestle for the required period of time On completion of the reaction as Table Reusability of Bi2O3 in the preparation of 2b using 60 mol% of the catalyst Entry Run number Time...

Ngày tải lên: 20/06/2014, 22:20

... distribution The inset of (b) shows the Au nanoparticle The inset of (c) corresponds to the EDX analysis of the Si NWs shows the histogram plot for the diameter distribution of the synthesized Si ... the pores of the AAO mask and will be responsible for the constant dimensions of the synthesized nanowires Figure shows the surface of the AAO-Si substrate, once the Figure Diagram of the CVD system ... growth The Si used in the growth process of nanowires is obtained from thermally generated defects on the surface of Si (100) These defects can be observed subsequently to the synthesis of Si...

Ngày tải lên: 21/06/2014, 01:20

... A3 The SiN layer underwent a swelling of about nm, whereas the thickness of the underlying HfO and SiO layers remain almost the same as in the as-deposited sample In contrast, HREM image of sample ... In the images, the surface of SiN layer is indicated by a white line accumulation layer of the substrate), resulting in a shift of the C-V curve toward negative voltages [21,22] In general, the ... prepared the draft of the manuscript Moreover, AS and CB participated in the coordination of study All authors read and approved the final manuscript Competing interests The authors declare that they...

Ngày tải lên: 21/06/2014, 05:20

... 2005) Reaction mechanism Formally, the reaction catalyzed by TAs can be considered a redox reaction with the oxidative deamination of the donor in conjunction with the reductive amination of the ... 2002) The reaction starts with the deamination of aspartate to α-ketoglutarate In the resting enzyme PLP is covalently bound to the ε-amino group of a lysine (Lys258) in the active site of the ... of Lys258 then acts as a catalyst for the 1,3-prototropic shift to form the ketimine The ketimine is hydrolyzed to yield the keto acid and PMP The following second half reaction consists of the...

Ngày tải lên: 21/06/2014, 17:20

... study the influence of growth temperature on the purity of prepared tube samples, we give the curve (Fig 4) showing the dependence of ID/IG on the growth temperature From Fig 4, two kinds of ID/IG ... accords with the result of the TEM image (Fig 3a) The intensity ratio, ID/IG, is observed to decrease with increasing temperature (at 800 °C, the ID/IG is 0.47) Raman spectrum of the sample grown ... cm-1 (the fundamental E2g mode of graphite) are presented In the lower wavenumber region (100–300 cm-1), the radial breath modes (RBM) which represent the existence of SWCNTs are hardly shown The...

Ngày tải lên: 22/06/2014, 00:20

... for 12 h (Fig 1b) The diameters of the nanoparticles are in the range of 50–70 nm with an average diameter of 60 nm Using higher reaction time of 24 h, the average diameter of the nanoparticles ... and nanoflowers by a soft reaction of nickel powder and water without using organic dispersant or capping agent To the best of our knowledge, this is the first report of synthesis where water is ... For the micro-structural analysis, the as-synthesized samples were directly transferred to the FESEM chamber without disturbing the original nature of the products Figure shows FESEM images of the...

Ngày tải lên: 22/06/2014, 01:20

... Dependence of carbon yield on the reaction temperature be through the precipitation of carbon in the form of MWNTs from the molten catalytic particles The melting temperatures of the alloy-C ... spectra of the alloy-filled MWNTs (Fig 2a) showed the presence of Zr, Cr, Fe and Ni; the constituents of the alloy, with a composition comparable to that of the initial alloy used for the preparation ... into the quartz tube for h at 500°C, in order to remove the presence of any oxygen on the surface of the alloy hydride catalysts Hydrogen flow was stopped and then furnace was heated up to the...

Ngày tải lên: 22/06/2014, 22:20

... by the weight of the original carbon on dry basis according with the following equation, (1) where W0 is the weight of the original carbon and W1 refers to the mass of the activated carbon The ... minor consumption of chemical compounds and a better elimination of the excess during the carbon washing process The effect of the increase in proportion of the impregnation over the carbon porous ... procedures An analysis of the experimental conditions used in the synthesis of ACs has been made attending to the carbon specific surface area Also, the advantages and disadvantages of each method are...

Ngày tải lên: 28/06/2014, 17:20

... INTRODUCTION THE CONDITIONS OF THE SYNTHESIS Chapter I Life and Yoga Chapter II The Three Steps of Nature Chapter III The Threefold Life 20 Chapter IV The Systems of Yoga 31 Chapter V The Synthesis of the ... Lord of the Sacrifice 106 Chapter V The Ascent of the Sacrifice – The Works of Knowledge — The Psychic Being 134 CONTENTS Chapter VI The Ascent of the Sacrifice – The Works of Love — The Works of ... itself 28 The Conditions of the Synthesis also to the alteration of the forms of our life and its institutions so that they too may be a better mould for the inpourings of the Spirit These attempts...

Ngày tải lên: 29/06/2014, 15:20

... gain insight into the mechanisms of these drugs on the OA subchondral bone osteoblasts, we further studied the effect of the therapeutic concentration of these drugs, 20 μg/mL, on the major intracellular ... from these studies support the beneficial effect of rhein on both the subchondral bone and the cartilage The mechanisms by which these drugs exert their effect occur through the downregulation of ... levels, by limiting the extent of the type I collagen degradation as well as the resorptive activity of the subchondral bone The role of cathepsin K in the remodelling of this tissue has been well...

Ngày tải lên: 09/08/2014, 10:23