Copper on kieselguhr

Chlorotrifluoromethane [75-72-9] M 104.5, m -180 , b -81.5 . Main impurities were CO2, O2, and N2. The CO2 was removed by passage through saturated aqueous KOH, followed by cone H2SO4. The O2 was removed using a tower packed with activated copper on Kieselguhr at 200°, and the gas dried over P2O5. 

CHij will give essentially the same reaction as SiHij, but the temperature required is 750 to 800°C, whereas other alkanes react at slightly lower temperatures (331). Some success has been achieved with certain other organic compounds at still lower temperatures, as with decomposing aldehydes and ketones and BCI3 or BBr3 in the presence of various catalysts. A 70% conversion to diborane is claimed for mixtures of the tribromide and formaldehyde when passed over a copper-on-kieselguhr catalyst at 400°C (122). 

Phosphates are the principal catalysts used in polymerization units the commercially used catalysts are Hquid phosphoric acid, phosphoric acid on kieselguhr, copper pyrophosphate pellets, and phosphoric acid film on quartz. The last is the least active and has the disadvantage that carbonaceous deposits must occasionally be burned off the support. Compared to other processes, the one using Hquid phosphoric acid catalyst is far more responsive to attempts to raise production by increasing temperature. 

Dicyclohexylarnine may be selectively generated by reductive alkylation of cyclohexylamine by cyclohexanone (15). Stated batch reaction conditions are specifically 0.05—2.0% Pd or Pt catalyst, which is reusable, pressures of 400—700 kPa (55—100 psi), and temperatures of 75—100°C to give complete reduction in 4 h. Continuous vapor-phase amination selective to dicyclohexylarnine is claimed for cyclohexanone (16) or mixed cyclohexanone plus cyclohexanol (17) feeds. Conditions are 5—15 s contact time of <1 1 ammonia ketone, - 3 1 hydrogen ketone at 260°C over nickel on kieselguhr. With mixed feed the preferred conditions over a mixed copper chromite plus nickel catalyst are 18-s contact time at 250 °C with ammonia alkyl = 0.6 1 and hydrogen alkyl = 1 1. 

For more selective hydrogenations, supported 5—10 wt % palladium on activated carbon is preferred for reductions in which ring hydrogenation is not wanted. Mild conditions, a neutral solvent, and a stoichiometric amount of hydrogen are used to avoid ring hydrogenation. There are also appHcations for 35—40 wt % cobalt on kieselguhr, copper chromite (nonpromoted or promoted with barium), 5—10 wt % platinum on activated carbon, platinum (IV) oxide (Adams catalyst), and rhenium heptasulfide. Alcohol yields can sometimes be increased by the use of nonpolar (nonacidic) solvents and small amounts of bases, such as tertiary amines, which act as catalyst inhibitors. 

Palladium and platinum (5—10 wt % on activated carbon) can be used with a variety of solvents as can copper carbonate on siHca and 60 wt % nickel on kieselguhr. The same is tme of nonsupported catalysts copper chromite, rhenium (VII) sulfide, rhenium (VI) oxide, and any of the Raney catalysts, copper, iron, or nickel. 

Carbon dioxide [124-38-9] M 44.0, sublimes at -78.5 . Passed over CuO wire at 800° to oxidise CO and other reducing impurities (such as H2), then over copper dispersed on Kieselguhr at 180° to remove oxygen. Drying at -78° removed water vapour. Final purification was by vacuum distn at liquid nitrogen temperature to remove non-condensable gases [Anderson, Best and Dominey JCS 3498 1962]. 

The reduction of aldols and ketols from the aldol condensation (method 102) is often a convenient route to branched 1,3-dio/s. Catalytic hydrogenation over platinum oxide, nickel-on-kieselguhr, and copper-chromium oxide has been used. Other procedures include electrolytic reduction and reduction by aluminum amalgam. 1,3-Diols may also be prepared by catalytic reduction of 1,3-diketones. Cleavage of the carbon-to-carbon and carbon-to-oxygen bonds accompanies this conversion. The effect of structure on the course of the reaction has been studied. ... 

Oxygen is best removed from larger amounts of nitrogen by passage through a copper tower in which the oxygen is bound on copper that is precipitated on kieselguhr and heated at 170°.50c 52... 

Dehydration of tetrahydropyran-2-methanol over high purity ij-alumina without any carrier gas produced cyclopentane carbaldehyde in a yield of 71 % at 603 K, while dehydration over copper-chromia oxide supported on kieselguhr with hydrogen carrier gas at 703 K yielded 2,3,4,5-tetrahydrooxepine and cyclopentanecarbaldehyde (44.8% and 4.7%, respectively). ... 

Hydrogenation. Hydrogenation is one of the oldest and most widely used appHcations for supported catalysts, and much has been written in this field (55—57). Metals useflil in hydrogenation include cobalt, copper, nickel, palladium, platinum, rhenium, rhodium, mthenium, and silver, and there are numerous catalysts available for various specific appHcations. Most hydrogenation catalysts rely on extremely fine dispersions of the active metal on activated carbon, alumina, siHca-alumina, 2eoHtes, kieselguhr, or inert salts, such as barium sulfate. 

For example, while reaction of 2-butoxynaphtalene with copper(II) bromide in benzene at 50°C for 2 h. produced only 6 % yield of l-bromo-2-butoxynaphtalene, similar reaction with Kieselguhr-supported copper(II) bromide gave 86 % yield of the monobromide. On the other hand, reaction using alumina as a support in benzene proceeded completely even at 10°C in 1 h. to give in addition to the monobromide (77 %), the dibromide (21 %) and the binaphtyl (2 %). 

The hydrogenation step talces place in the conventional way in vessel packed with catalyst where the aldehydes and hydrogen are admixed at 200-300°F and 600-1200 psi. The catalyst is usually nickel or copper chromite on an inert carrier such as kieselguhr, silica gel, or alumina. The crude butyl alcohols are finally separated and purified by distillation. 

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