Barium chloride, catalysts

The palladium - barium sulphate catalyst Is prepared by treating a suspension of20g. of barium sulphate (which has been precipitated in hot solution) in 400 ml. of hot water with a solution of I - 7 g. of palladium chloride (equivalent to I - 0 g. of palladium) in 50 ml. of water and with I - 5 ml. of 40 per cent, formaldehyde solution. The mixture is rendered faintly alkaline to litmus by the addition of sodium hydroxide solution and then boiled for a short time. When the supernatant liquid is clear, the grey precipitate is filtered oS, and wa.shed with hot water until the... 

Ethyl chloride can be dehydrochlorinated to ethylene using alcohoHc potash. Condensation of alcohol with ethyl chloride in this reaction also produces some diethyl ether. Heating to 625°C and subsequent contact with calcium oxide and water at 400—450°C gives ethyl alcohol as the chief product of decomposition. Ethyl chloride yields butane, ethylene, water, and a soHd of unknown composition when heated with metallic magnesium for about six hours in a sealed tube. Ethyl chloride forms regular crystals of a hydrate with water at 0°C (5). Dry ethyl chloride can be used in contact with most common metals in the absence of air up to 200°C. Its oxidation and hydrolysis are slow at ordinary temperatures. Ethyl chloride yields ethyl alcohol, acetaldehyde, and some ethylene in the presence of steam with various catalysts, eg, titanium dioxide and barium chloride. 

D, Palladium on barium sulphate catalyst (5 per cent. Pd). (4) Prepare a solution of 4-1 g. of anhydrous palladium chloride (1) in 10 ml. of concentrated hydrochloric acid and 25 ml. of water (as in A). Add all at once 60 ml. of 6.sulphuric acid to a rapidly stirred, hot (80°) solution of 63-1 g. of A.R. crystallised barium hydroxide in 600 ml. of water contained in a 2-litre beaker. Add more 6.sulphuric acid to render the suspension just acid to litmus (5). Introduce the palladium chloride solution and 4 ml. of 37 per cent, formaldehyde solution into the hot mechanically-stirred suspension of barium sulphate. Render the suspension slightly alkaline with 30 per cent, sodium hydroxide solution, continue the stirring for 5 minutes longer, and allow the catalyst to settle. Decant the clear supernatant liquid, replace it by water and resuspend the catalyst. Wash the catalyst by decantation 8-10 times and then collect it on a medium - porosity sintered glass funnel, wash it with five 25 ml. portions of water and suck as dry as possible. Dry the funnel and contents at 80°, powder the catalyst (48 g.), and store it in a tightly-stoppered bottle. 

A clearer picture emerges from studies of substituent effects on the rate with a single catalyst. A series of alkyl chlorides (C2 to C6) was decomposed on a barium sulphate catalyst [184] and the rate data were correlated by the Taft equation. Large negative values of p were obtained, viz. —34.3 at 220°C and —40.3 at 280°C. Similarly, for a series of three alkyl bromides (ethyl, propyl and isopropyl) on silica—alumina, alumina—... 

For use in the Rosenmund reduction (Expt 6.120) the catalyst is moderated by the addition of the appropriate quantity of a quinoline-sulphur poison prepared in the following manner. Heat under reflux 1 g of sulphur with 6g of quinoline for 5 hours and dilute the resulting brown liquid to 70 ml with xylene which has been purified by distillation over anhydrous aluminium chloride. Thiourea (about 20% by weight of the palladium-barium sulphate catalyst) may also be used as a catalyst poison. 

Fit a 250-ml three-necked flask with a reflux condenser, a high-speed sealed stirrer (1) and a gas inlet tube extending to a point just above the bottom of the stirrer. Place 28.5 g (0.15 mol) of 2-naphthoyl chloride (Expt 6.161), 100 ml of sodium-dried xylene, 3 g of palladium-barium sulphate catalyst and 0.3 ml of the stock poison solution (Section 4.2.54, p. 452) in the flask. Connect the top of the condenser by a rubber tube to a 6-mm glass tube extending to the bottom of a 250-ml conical flask containing 200 ml of distilled water and a few drops of phenolphthalein indicator arrange a burette charged with c. 1m sodium hydroxide solution (prepared from the pure solid) for delivery into the flask. The apparatus must be sited in the fume cupboard. 

Additives are also used to improve the solubility of halide donors [382, 383]. Metal(II) halides such as magnesium chloride, calcium chloride, barium chloride, manganese chloride, zinc chloride and copper chloride etc. are used as halide sources. In order to increase the solubility of the halides they are reacted with electron donors which have been previously described for the increase of solubility of Nd-components [338,339]. The number of catalyst components is further increased if two Al-compounds (alumoxane + aluminum (hydrido) alkyl) are used. In addition, a small amount of diene can also be present during the preformation of the different catalyst components as described by JSR. In some catalyst systems the total number of components reaches up to eight [338,339]. Such complex catalyst systems are also referred to in other JSR patents [384,385] (Sect. 2.2.6). 

Sodium oxalate has been used as a primary standard substance for Ce(IV) in sulfuric acid. In the absence of a catalyst a temperature of 70 to 75°C is necessary. Smith and Getz found that in 1 to 2 M perchloric acid solution, sodium oxalate can be titrated at room temperature with Ce(IV) perchlorate or nitrate but not with sulfate. Rao, Rao, and Rao carried out the titration at room temperature in the presence of barium chloride to remove sulfate, which retards the reaction between oxalate and Ce(IV) and between oxalate and oxidized ferroin. Alternatively, some Fe(III) was added, and the trace of Fe(II) produced photochemically then reacted with the indicator. Rao, Rao, and Murty carried out the titration in 0.5 M HNOj with ammonium hexanitratocerate(IV) instead of the sulfate. With a small amount of KI and KIO3, a satisfactory end point was obtained at room temperature with ferroin as indicator. 

Rosenmund reduction The reduction of an acyl chloride to an aldehyde by hydrogenation using a palladium on barium sulphate catalyst. 

Surface grafting of barium sulfate is interesting Ifom the point of view of the kinetics of such reactions. Barium sulfate like calcium carbonate, is an inert filler. So it is necessary to modify its surface. First, barium chloride is reacted with sodium sulfate in the presence of a small amount of sodium 12-hydroxystearate. This introduces a controlled number of hydroxyl stearate sites onto the barium sulfate surface. The reaction is followed by a redox graft polymerization of acrylamide initiated by the hydroxyl stearate groups and ceric ion as a catalyst. Figures 6.9 to 6.11 show the effect of reaction substrates concentrations on polymerization rate. 

Acid Chlorides. Compounds in this class undergo selective hydrogenation in the presence of a palladium on barium sulfate catalyst to yield the corresponding aldehyde. A poison or regulator such as thioquin-anthrene is necessary to prevent further reduction of the aldehyde. This procedure is known as the Rosenmund reaction. ... 

Rosenmund Reaction. A catalyst poison prepared from quinoline and sulfur is useful for controlling the reaction of p-naphthoyl chloride (19) with hydrogen gas and palladium on barium sulfate catalyst. If control of the reaction is not maintained by catalyst poisoning to reduce activity, further reduction beyond the desired /3-naphthaldehyde product (20) is often observed (eq 13). ... 

It was observed that the most efficient oxidant was KMnO absorbed on a fourfold molar amount of CUSO4.5H2O (100% yield), but attempts were made to oxidize 2-heptanol, under solvent-free conditions, by KMnO alone (i.e., in the absence of the support of an inorganic salt hydrate) were absolutely unsuccessful. Various inorganic salts were tried and yielded varied amounts of the product. The better supports include nickel sulfate (90%), zinc sulfate (74%), and cobalt sulfate (41%) while other supports were not that interesting like magnesium sulfate (12%), calcium sulfate (11%) and barium chloride (3%). Zeolite HZSM-5 was used as a catalyst for the oxidation of alcohols to the corresponding carbonyl compound with chromium trioxide under solvent-free conditions and microwave irradiation (Heravi et al., 1999). 

From acid chlorides by selective hydrogenation in the presence of a catalyst (palladium deposited upon a carrier, which is usually barium sulphate but is... 

The palladium may be recovered by heating the spent catalyst to redness in order to remove organic impurities this treatment may reduce some of the barium sulphate to barium sulphide, which acts as a catalytic poison. The palladium is then dissolved out with aqua regia and the solution evaporated the residue is dissolved in hot water and hydrochloric acid to form palladium chloride. 

Ultimately, as the stabilization reactions continue, the metallic salts or soaps are depleted and the by-product metal chlorides result. These metal chlorides are potential Lewis acid catalysts and can greatiy accelerate the undesired dehydrochlorination of PVC. Both zinc chloride and cadmium chloride are particularly strong Lewis acids compared to the weakly acidic organotin chlorides and lead chlorides. This significant complication is effectively dealt with in commercial practice by the co-addition of alkaline-earth soaps or salts, such as calcium stearate or barium stearate, ie, by the use of mixed metal stabilizers. 

Palladium catalysts have been prepared by fusion of palladium chloride in sodium nitrate to give palladium oxide by reduction of palladium salts by alkaline formaldehyde or sodium formate, by hydrazine and by the reduction of palladium salts with hydrogen.The metal has been prepared in the form of palladium black, and in colloidal form in water containing a protective material, as well as upon supports. The supports commonly used are asbestos, barium carbonate, ... 

Resoles are usually those phenolics made under alkaline conditions with an excess of aldehyde. The name denotes a phenol alcohol, which is the dominant species in most resoles. The most common catalyst is sodium hydroxide, though lithium, potassium, magnesium, calcium, strontium, and barium hydroxides or oxides are also frequently used. Amine catalysis is also common. Occasionally, a Lewis acid salt, such as zinc acetate or tin chloride will be used to achieve some special property. Due to inclusion of excess aldehyde, resoles are capable of curing without addition of methylene donors. Although cure accelerators are available, it is common to cure resoles by application of heat alone. 

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