Sequential conversion

TXA2 is produced by activated platelets via the sequential conversion of arachidonic acid by phospholipase A2, cyclooxygenase-1 (COX-1), and thromboxane synthase. Similar to ADP, TXA2 acts as a... 

Figure 11, Sequential conversion of coal to distillable products, char, and gas under alternate reaction conditions...

Cytosol conversion of styrene 7,8 epoxide to styrene 7,8 glycol Sequential conversion of nitrobenzene to aniline... 

Hydrodemetallation reactions require the diffusion of multiringed aromatic molecules into the pore structure of the catalyst prior to initiation of the sequential conversion mechanism. The observed diffusion rate may be influenced by adsorption interactions with the surface and a contribution from surface diffusion. Experiments with nickel and vanadyl porphyrins at typical hydroprocessing conditions have shown that the reaction rates are independent of particle diameter only for catalysts on the order of 100 /im and smaller (R < 50/im). Thus the kinetic-controlled regime, that is, where the diffusion rate DeU/R2 is larger than the intrinsic reaction rate k, is limited to small particles. This necessitates an understanding of the molecular diffusion process in porous material to interpret the diffusion-disguised kinetics observed with full-size (i -in.) commercial catalysts. 

Fig. 1 Scheme of the sequential conversion of glycerol to give an oxygen depletion... 

This experiment allows you to carry out the sequential conversion of copper metal to copper(II) nitrate to copper(II) hydroxide to copper(II) oxide to copper(II) sulfate and back to copper metal. This conversion is carried out using synthesis, decomposition, single displacement, and double displacement reactions. 

Within 1 h of exposure to carbofuran (1.5mg/kg, s.c.), CK activity was significantly reduced in soleus, while increased in diaphragm. At the same time, activities of CK and all three CK isoenzymes were significantly elevated in serum. An important finding was that carbofuran or methyl parathion caused a shift in the serum CK-MM subform, i.e. higher sequential conversions of CK-MM3 subform to CK-MM2 and CK-MM2 to CK-MMl, possibly due to enhanced carboxypeptidase-N2 activity (Gupta et al, 1994). 

The isomerization reaction that leads to the production of positional isomers (Reaction 3) has similar first-order kinetics. Using this assumption, we have modeled the sequential conversion of linoleyl soaps to a mixture of 9,11-cw-, trans-octadecadienoyl and Q, 2-trans-, cw-octadecadienoyl soaps (Reaction 2) and finally, the conversion of these two soaps to 8,10-octadecadienoyl and 11,13-octadeca-dienoyl soaps. Reaction 3 shows the mechanism of one of these two isomerization processes. 

Trans hydroxylation of an alkene involves sequential conversion to an oxirane (epoxide), and its conjugate acid, followed by nucleophilic opening of the oxirane by water... 

Sequential conversion of DHA into the hydrazone 60, followed by oximation gave the oxime 71c (77ACH409 88MI4), then cyclodehydration gave 4-L-t/ireo-2,3-di-acetoxy-(l-hydroxypropyl)-2-phenyl-l,2,3-triazole-... 

Kagan and co-workers pioneered the work on the reductive behavior of the low oxidation states of the lanthanide elements in organic synthesis [2b]. Ln metals and Ln(II) derivatives were subsequently found to promote a number of important individual reactions [301]. The combination of one- and two-electron chemistry sets Sml2 apart from virtually every other reductive coupling agent currently available and exhibits exceptional properties for sequential conversions tolerating unprotected functional groups [lb]. 

Fig. I. The xamhophyll cycle and its effects on light-harvesting and energy dissipation within the photosynthetic apparatus. The enzyme violaxanthin de-epoxidase (VDE) catalyzes the sequential conversion of violaxanthin to zeaxanthin via antheraxanthin using ascorbic acid (AA) as a reductant and generating monodehydroascorbate (MDHA). The epoxidation of zeaxanthin to violaxanthin in the reverse reaction sequence is catalyzed by the enzyme zeaxanthin epoxidase (ZE).

The clotting cascade is a sequential conversion of inactive plasma factors to active factors, resulting in the ultimate conversion of soluble fibrinogen to insoluble fibrin. This fibrin forms the basis of clot formation. 

The normal route for (3 oxidation in bacteria utilizes acyl CoA derivatives, which are formed from free fatty acids. To convert a primary alcohol to a free fatty acid, two oxidative steps are needed, each requiring an electron acceptor. In corynebacterium, NAD -dependent dehydrogenases catalyze the sequential conversion of a primary alcohol to a fatty acid, with the corresponding aldehyde as an intermediate. Conversion of the free fatty acid to an acyl CoA derivative requires two equivalents of ATP (because ATP is converted to AMP and PPj), as well as coenzyme A. The reaction is catalyzed by acyl CoA synthase. 

Chang, T.M.S., Malouf, C. and Resurrecclon, E., Artificial cells containing multienzyme systems for the sequential conversion of urea Into ammonia, glutamate, then alanine. 

Ethionamide (2-ethylthioisonicotinamide, Trecator SC, 8) is an antibiotic prodrug used in the treatment of tuberculosis. One synthetic pathway involves the condensation of diketo-ester 160 with cyanoacetamide 161 followed by hydrolysis of the resulting pyridone 162 into give pyridone acid 163. Treatment of 163 with POCI3 converts the lactam to imine chloride and simultaneous ester formation in ethanol to give 164. Hydrogenation of 164 to remove the chloride, amide formation, and sequential conversion to the thioamide provided 8." ... 

When coal is heated in a slurrying vehicle, it is liquefied at 400°C-500°C (750°F-930°F). Though the reaction mechanism involving conversion of coal to oil is very complex, it appears that the interaction of coal with solvent at the initial stage of the reactions plays the vital role to determine the sequential conversion of coal substances—first to a pyridine-soluble solid and thereafter to benzene-soluble liquid hydrocarbons and low-boiling products. Thus the isolation and identification of the products of coal-solvent interactions to yield pyridine-soluble matter may provide information regarding the suitability of the coal for liquefaction. 

A facile synthesis of allenic esters (187) is by reaction between acid chlorides (185) and phosphoranes (186) derived from a-halo-esters. Yields are 10— 70% presumably ketens are intermediates. Cyclic /3-keto-esters can serve as precursors to cyclic allenic esters by sequential conversion to the 2-pyrazolin-5-one derivatives, using hydrazine and oxidation with thallium trinitrate (Scheme 26) overall yields are around 50%. ... 

Carlsson M, Habenicht C, Kam LC, Antal MJ, Bian N, Cunningham RJ, Jones M Jr (1994) Study of the sequential conversion of citric acid to itaconic to methacrylic acid in near-critical and supercritical water. Ind Eng Chem Res 33 1989-1996... 

Another interesting transformation that involves the sequential conversion of acetylide into ketenyl and alkylidyne was observed in 202. The oxidation of 202 in toluene produced the ketenyl complex 203, which underwent CO dissociation to give the alkylidyne cluster 204. ... 

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