Selectivity carbon

An improved method iavolves the reaction of a chlorohydrin and CO2 ia the presence of an amine, which gives cycHc carbonate selectivities of... 

Catechols can be protected as diethers or diesters by methods that have been described to protect phenols. However, formation of cyclic acetals and ketals (e.g., methylenedioxy, acetonide, cyclohexylidenedioxy, diphenylmethylenedioxy derivatives) or cyclic esters (e.g., borates or carbonates) selectively protects the two adjacent hydroxyl groups in the presence of isolated phenol groups. 

Formation of diamines from dinitro compounds, which are unable to interact intramolecularly, presents no problem. Very large volumes of diaminotoluene, a precursor to toluene diisocyanate, are produced by hydrogenation of dinitrotoluene over either nickel or palladium-on-carbon. Selective hydrogenation of one or the other of two nitro groups is much more of a challenge, but a number of outstanding successes have been recorded. A case in point is the hydrogenation of 2,4-dinitroaniline (11) to 4-nitro-l,2-benzenediamine (12) (2) or to 2-nitro-l,4-benzenediamine (10). 

The monoacetate 9a (R1 = Ac) and the diacetate 10a (R1 = R2 = Ac) are obtained by treatment of 8 with acetic anhydride in anhydrous pyridine at room temperature 4 the oxo group in position 5 of 8 is more reactive towards acetylation. Similarly, the S,S-dioxidc of 8 can be converted to the bisacetylated S,5-dioxide of 10a in 78 % yield.74 Methylation of 8 with diazomethane gives 9c (65 % yield), along with 14 % of the 3-methoxy compound 11. Other alkylation agents, such as dimethyl sulfate in the presence of potassium carbonate, selectively give 9c, albeit in lower (30 %) yield.90 The dimethyl enol ether 10c (R1 = R2 = Me) is obtained by a subsequent methylation of 9c (R1 = Me) with dimethyl sulfate and potassium teri-butoxide.90... 

Next, we investigated the effect of input power on ps formation rates and on carbon-selectivity. As shown in Fig. 3, the amount of product inerrased as the input powear increased. The selectivity to carbon monoxide and C2 hydrocarbons was constant despite the change of the input power. These results showed m identical trend to that of the gas phase... 

Fig. 4. Effect of pinluile diameter on gaseous formation rates ai on carbon selectivity O, energy efficiency basal on LHV A, aietgy efficiency based on HHV , uqnit power 9, H2 formation rate A, CO formation rate gap distaiKe 6.0 mm QjHsOH cone., 50 mol% diaphragm fhickness, 1.0 mm.

The dominant factors reversing the conventional ds-hydroboration to the trans-hydroboration are the use of alkyne in excess of catecholborane or pinacolborane and the presence of more than 1 equiv. of EtsN. The P-hydrogen in the ris-product unexpectedly does not derive from the borane reagents because a deuterium label at the terminal carbon selectively migrates to the P-carbon (Scheme 1-5). A vinylidene complex (17) [45] generated by the oxidative addition of the terminal C-H bond to the catalyst is proposed as a key intermediate of the formal trans-hydroboration. 

In spite of the apparent simplicity of the method, its drawback comes from the fact that a two-spin system has been assumed. It provides merely global information spanning all protons prone two interact by dipolar coupling with the considered carbon. Selective information requires pulsed experiments stemming from the general solution of Equation (14) given below. 

The carbon selectivity SCi of hydrocarbons of carbon number i is defined by the mass of carbon in the components related to the mass of carbon of all hydrocarbons in the 3 to 40 carbon number range. The slopes of the straight lines in the diagram log(SCi/i) vs. the carbon number i give cij and a2. In Figures 11.1 and 11.2 the open symbols represent SCi x/i of distribution 1, which is the difference of... 

Yong Suk Choi et al. [26] used a carbonate-selective electrode to determine dissolved carbon dioxide in the oceans. 

Alkene conversion to epoxide (%) Epoxide selectivity (%) Epoxide conversion (%) Cyclic carbonate selectivity (%)... 

Nucleophilic Reactions.—Attack on Saturated Carbon. Selected examples of the Arbusov reaction include phosphorylation of the chloroacetophenones (1) to give phosphonates, which cyclized to (2) in the presence of acid chlorides,1 formation of the azodiphosphonate (3) from 2,2 -dichloro-2,2 -azopropane,2 3 and the reaction of 2-chloro-3,4-dihydro-3-oxo-2//-l,4-benzothiazine (4) with triethyl phosphite to give the 2-phosphonate (5), which is used as an olefin synthon.8 Bis(trimethylsilyl) trimethylsiloxymethylphosphonite (6) has been synthesized by silylation of hydroxy-methylphosphonous acid, and, as expected, undergoes a normal Arbusov reaction with alkyl halides to give the phosphonates (7).4 This series of reactions, followed by... 

Paracrystallinity, Cu/ZnO/AIjOj, 31 295 2"-Paracyclophanes, 32 453 Paracyclophanes, macrocycles, 29 206-208 Paraffin, see also Alkanes alkylation, 10 165, 27 98 carbon selectivity, bed residence time effects, 39 249-250 cracking, 39 283 cyclization, 28 295 rates, 28 301, 302 double cyclization, 28 312-314 in exhaust gases, 24 66, 67 hydrogenolysis, 30 43-44 hydroisomerization, 39 183 oxidation, 32 118-121 solubility enhanced hydrogeolysis, 39 285 Parahydrogen conversion rate correlations, 27 48-50... 

After more than a decade of exploration, the skeletal components of the electrolyte for the commercialized lithium ion devices have been identified. Within the various brands of lithium ion cells, the exact electrolyte composition differs from manufacturer to manufacturer, and the formulas remain proprietary information however, the overwhelming majority of these are apparently based on two indispensable components EC as the solvent and LiPFe as the solute. In most cases, one or more linear carbonates, selected from DMC, DEC, or EMC, are also used as cosolvents to increase the fluidity and reduce the melting point of the electrolyte, thus forming the popular composition consisting of LiPFe/ EC/linear carbonate (s). 

Chelation is not necessary to promote the abnormal metallation. When imidazo-lium salts with bulky substituents (e.g. iPr, tBu) are refluxed with pyridine and lrH5(PPh3)2 in tetrahydrofuran (THF), aNHC complexes are obtained in good yields, with the least sterically hindered of the three imidazolium carbons selectively bound to the metal (Scheme 3.13) [29]. Infrared spectroscopy on carbonyl... 

Feed composition effects on cross-over points were investigated by cracking a heavy gas oil (with API gravity of 23.7) containing 71% slurry oil. The high (34%) aromatics content of this feed is believed responsible for the greater coke make and increased deactivation rate of the host catalyst. As a result, a cross-over point below 0.25 wt% vanadium is obtained, see Figure 6. A loss of carbon selectivity is observed also in the DFCC mixture. In fact. 

Iron impurities in clays have been thought responsible for these type of catalysts low carbon selectivity (4,5). The purpose of this paper is to investigate and report the influence that the location, chemical state and environment of iron impurities have on the cracking properties of pillared clays prepared by reacting several smectites with aluminum chlorhydroxide solutions. 

The ruthenium(111) acetylacetonate-cobalt(II) iodide couple, for example, when dispersed in tetrabutylphosphonium bromide (ex. 1) and treated with 1/1 CO/H2 at 220°C, generates a liquid product containing 76 wt % acetic acid plus 1.1 wt % propionic acid (111 mmol total acid). The liquid yield increase is 66% and the estimated carbon selectivity to acetic plus propionic acids and their esters is 84%. There is normally no metallic residue at this stage, ruthenium and cobalt recovery is essentially quantitative at the end of the run, and the product acids may be recovered in >90% purity by fractional distillation. Methane and water are the major by-products (4). 

Reactivity of enols and enolates at carbon. Selectivity in reactions by ... 

Catalyst Temp. (°C) MeOH conversion Hydrogen Selectivity (mol %) Carbon Selectivity (mol %) H/4C... 

The influence of the ester selectivity is even more pronounced when a phenyl group is present on the /3 carbon selectivity decreases further... 

Fig. 5.1. C NMR spectra of 5a-cholcstan-3-onc in dcutcriochloroform (50 mg/0.5 mL) (a) proton broadband-decoupled, 400 scans (b). /-modulated spin-echo experiment for quaternary carbon selection, 1000 scans (c-e) CH, Cl I2, and CH3 subspectra generated from linear combination of three DEPT experiments (see Section 2.9.3.2), 200 scans per experiment (f) gated proton-decoupled experiment for comparison.

Graphite composites Polished Wide solvent compatability, increased signal/background current, easy chemical modification Binder can coat carbon Selectivity can be varied with chemical modification 3... 

Catalyst Conversion of alcohol [%) Yield (%) of carbonate Selectivity of carbonate (%)... 

J.E. Koresh and A. Soffer, Molecular Sieve Carbon Selective Membrane, Sep. Sci. Technol. 18, 123 (1983). 

The carbon selected for study is a coal based, high activity (109 %CTC), extruded carbon (2 mm diameter pellets) from Sutcliffe Speakman (Tarbons Ltd (SSC). The carbon was characterized using N2 adsorption at 77 K and mercury porosimetiy. An analysis of the chemical nature of the carbon surface using the PZC method and Bohem titration revealed that its surface is mostly clean of acidic groups. 

Ru content (wt%) Ru dispersion" Ru-time yield (10 s- ) Site-time yield (10 s" ) Carbon selectivity (%) ... 

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