Chlorine/chloride products

The use of platinum and palladium is limited by cost and sensitivity of the noble metal catalysts to poisoning, especially by chlorine/chloride products. Thus, non-noble... 

Because of its relatively high, price, there have been continuing efforts to replace acetylene in its major appHcations with cheaper raw materials. Such efforts have been successful, particularly in the United States, where ethylene has displaced acetylene as raw material for acetaldehyde, acetic acid, vinyl acetate, and chlorinated solvents. Only a few percent of U.S. vinyl chloride production is still based on acetylene. Propjiene has replaced acetylene as feed for acrylates and acrylonitrile. Even some recent production of traditional Reppe acetylene chemicals, such as butanediol and butyrolactone, is based on new raw materials. 

Most HCl generated during chlorinated C production is recycled to make methyl chloride. 

Methyl Chloride. Most of the HCl consumed in the manufacture of methyl chloride [74-87-3] from methanol (qv) is a recycled product. The further reaction of methyl chloride with chlorine to produce higher chlorinated methanes generates significant amounts of HCl which are fed back into methyl chloride production. Another source of recycled HCl is siUcone production based on methyl chloride. 

In a typical balanced plant producing vinyl chloride from EDC, all the HCl produced in EDC pyrolysis is used as the feed for oxychlorination. On this basis, EDC production is about evenly spHt between direct chlorination and oxychlorination, and there is no net production or consumption of HCl. The three principal operating steps used in the balanced process for ethylene-based vinyl chloride production are shown in the block flow diagram in Eigure 1, and a schematic of the overall process for a conventional plant is shown in Eigure 2 (76). A typical material balance for this process is given in Table 2. 

Chlorinated by-products of ethylene oxychlorination typically include 1,1,2-trichloroethane chloral [75-87-6] (trichloroacetaldehyde) trichloroethylene [7901-6]-, 1,1-dichloroethane cis- and /n j -l,2-dichloroethylenes [156-59-2 and 156-60-5]-, 1,1-dichloroethylene [75-35-4] (vinyhdene chloride) 2-chloroethanol [107-07-3]-, ethyl chloride vinyl chloride mono-, di-, tri-, and tetrachloromethanes (methyl chloride [74-87-3], methylene chloride [75-09-2], chloroform, and carbon tetrachloride [56-23-5])-, and higher boiling compounds. The production of these compounds should be minimized to lower raw material costs, lessen the task of EDC purification, prevent fouling in the pyrolysis reactor, and minimize by-product handling and disposal. Of particular concern is chloral, because it polymerizes in the presence of strong acids. Chloral must be removed to prevent the formation of soflds which can foul and clog operating lines and controls (78). 

By-products from EDC pyrolysis typically include acetjiene, ethylene, methyl chloride, ethyl chloride, 1,3-butadiene, vinylacetylene, benzene, chloroprene, vinyUdene chloride, 1,1-dichloroethane, chloroform, carbon tetrachloride, 1,1,1-trichloroethane [71-55-6] and other chlorinated hydrocarbons (78). Most of these impurities remain with the unconverted EDC, and are subsequendy removed in EDC purification as light and heavy ends. The lightest compounds, ethylene and acetylene, are taken off with the HCl and end up in the oxychlorination reactor feed. The acetylene can be selectively hydrogenated to ethylene. The compounds that have boiling points near that of vinyl chloride, ie, methyl chloride and 1,3-butadiene, will codistiU with the vinyl chloride product. Chlorine or carbon tetrachloride addition to the pyrolysis reactor feed has been used to suppress methyl chloride formation, whereas 1,3-butadiene, which interferes with PVC polymerization, can be removed by treatment with chlorine or HCl, or by selective hydrogenation. 

Dichloroethane, an important intermediate for vinyl chloride production, is produced by catalytic chlorination of ethylene in either vapor or Hquid phase or by oxychlorination of ethylene. Thermal dehydrochlorination of 1,2-dichloroethane produces vinyl chloride and coproduct hydrogen chloride. Hydrogen chloride is commonly recycled to an oxychlorination unit to produce 1,2-dichloroethane or is processed into sales-grade anhydrous or aqueous hydrogen chloride. 

Producers. In the years since 1945, production capacities and the number of producing companies have substantiaHy increased however the high temperature chlorination reaction has remained the exclusive technique for commercial production of aHyl chloride. Production facHities thought to be in existence in 1990 are Hsted in the foHowing, in order of estimated production capacities (40—48). 

Benzyl chloride is manufactured by the thermal or photochemical chlorination of toluene at 65—100°C (37). At lower temperatures the amount of ring-chlorinated by-products is increased. The chlorination is usually carried to no more than about 50% toluene conversion in order to minimize the amount of benzal chloride formed. Overall yield based on toluene is more than 90%. Various materials, including phosphoms pentachloride, have been reported to catalyze the side-chain chlorination. These compounds and others such as amides also reduce ring chlorination by complexing metallic impurities (38). 

Benzotrichloride is produced from total side-chain chlorination of toluene or of residual products from benzyl chloride production. In Western Europe, Bayer has the largest capacity (14,000 t/yr), and there are only two significant producers in the United States Occidental Chemical in Niagara EaUs, New York (20,000 t/yr), and Velsicol Chemical (11,000 t/yr). Total capacity in the western world is 68,000 t/yr and production of benzotrichloride in 1988 was estimated at 31,500 t. 

Cupric chloride can be used, but it tends to chlorinate the products and cuprous chloride is preferable reagent grade dimethylformamide (DMF) was distilled before use. 

In the 1960s materials became available which are said to have been obtained by chlorination at lower temperatures. In one process the reaction is carried out photochemically in aqueous dispersion in the presence of a swelling agent such as chloroform. At low temperatures and in the presence of excess chlorine the halogen adds to the carbon atom that does not already have an attached chlorine. The product is therefore effectively identical with a hypothetical copolymer of vinyl chloride and symmetrical dichloroethylene. An increase in the amount of post-chlorination increases the melt viscosity and the transition temperature. Typical commercial materials have a chlorine content of about 66-67% (c.f. 56.8% for PVC) with a Tg of about 110% (c.f. approx. 80°C for PVC). 

Ni-Cr-Mo Ni-Mo Ni-Cu Chlorination processes Processes involving HCl and nonoxidising acidic chlorides Production and Distillation columns containing acidic chlorides HF alkylation Fluorination Applications where no pitting and no loss of reflectivity are necessary Valves, Bleaching operations Handling Pickling of... 

Hydrogen chloride Production Absorbers, coolers, strippers, chlorine burners, complete plants... 

Freshly distilled allene should be used. It should be free of 2-chloropropene, usually present in allene prepared by zinc dehalogenation of 2,3-dichloropropene,3 to avoid formation of chlorine-containing products that liberate hydrogen chloride on distillation. 

When 2.36 g of phosphorus was burned in chlorine, the product was 10.5 g of a phosphorus chloride. Its vapor rook 1.77 times as long to effuse as the same amount of CO, under... 

The sulfur chloride (S2C12) volatilizes along with the ferric chloride (FeCl3) and the cupric chloride (CuCl2) remains in the residue. When the reaction is conducted at 600 °C with a limited supply of chlorine, the products are different ... 

Unused reactants can be recycled and off-specification product reprocessed. Integrated processes can be selected the waste from one process becoming the raw material for another. For example, the otherwise waste hydrogen chloride produced in a chlorination process can be used for chlorination using a different reaction as in the balanced, chlorination-oxyhydrochlorination process for vinyl chloride production. It may be... 

Benzisothiazoles (51) are available from the reaction of thionyl chloride with o-alkylbenzeneamines (o-toluidines).63 Chlorinated by-products are... 

The reaction of sulfuryl chloride with disaccharides is of current interest. Although chlorine-containing products were isolated earlier from this reaction with sucrose,350 their structures were not elucidated. Since then, one tetrachlorotetradeoxy- and two penta-... 

ACH (2) [Aluminium chlorohydrate] This is the common name for some types of basic aluminum chloride, but the name has been used also to designate the process by which such a product is made. Several processes are used to make the several commercial aluminum chloride products available, some of which are proprietary. In general it is necessary to introduce an excess of aluminum to a chloride solution, such that the atom ratio of aluminum to chlorine is less than three. The aluminum may be introduced as either the metal or the hydrated oxide. 

In the future it might be possible to see the gas diffusion technology generating chlorine with energy consumption at 1500 kWh. The chlorine will be used in the direct chlorination of ethane to feed the vinyl chain. Side streams of HC1 will be used in oxychlorination where ethylene is available and this will use up by-product acid from isocyanates. Site integration will increase to benefit from economies of scale and optimise hydrogen chloride production. 

The efficiency of nitrobenzene photoreduction may be increased remarkably in 2-propanol/hydrochloric acid mixtures. In 50% 2-propanol/water containing 6 moles l i HCl, acetone and a complex mixture of chlorinated reduction products are formed i ). Both HCl and 2-propanol (as hydrogen source) are needed. When sulfuric acid is substituted for HCl, enhanced photoreduction does not occtu . When using mixtures of HCl and LiCl to maintain a constant chloride concentration (6 M) and vary [H+], a constant disappearance quantum yield 366 =0.15 is found within the [H+]-range 0.05—6 moles l i. This strongly suggests that chloride ions play an essential role, probably via electron transfer to 3(n, tt )-nitrobenzene i > [Eq. (1)], but it is also evident from the data presented that the presence of add is probably important in subsequent steps, [Eq. (3)]. 

P C with constant stirring via a magnetic stirrer. A slight excess of chlorine (10% mole excess) gas was bubbled through the solution with the liberated hydrogen chloride being trapped in the sodium hydroxide solution. The chlorinated rubber product was isolated as a white precipitate with addition of 90% ethanol. 

Reactions with most metals yield metal chlorides. Alkali metals are obviously most reactive. With metals that exhibit varying oxidation states, the nature of the product depends on the amount of chlorine. For example, iron reacts with a limited amount of chlorine to produce iron(II) chloride, while in excess chlorine the product is iron(III) chloride ... 

Chlorine may be regarded as a reactive intermediate in electrochemical processes and chlorination of many substrates can be achieved simply by in situ anodic generation of chlorine. Indeed, often electrolysis in the presence of chloride leads to mechanistic ambiguities and/or the formation of chlorinated side products [79]. 

All the halogen elements combine with tellurium. The powdered crystalline form is inflamed by fluorine in the cold 1 and by warm chlorine, the product in the latter case being the tetrachloride.2 With bromine the product is the dibromide, whilst iodine reacts only at a higher temperature, giving a tetra-iodide. Hydrogen chloride does not affect the element. 

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