Production of Hydrogen Chloride

The manufacture of hydrogen chloride by the decomposition of sodium chloride with sulphuric acid 

Formerly, hydrogen chloride was produced as a by-product of the first stage of the Leblanc soda ash process, based on the reaction  

The Leblanc process has been given up but decomposition of sodium chloride with sulphuric acid has not been abandoned, as a way has been found to utilize the by-product of this reaction, i. e. sodium sulphate, in the glass industry and other industries. 

Actually, the decomposition of sodium chloride is not so simple as it may appear from the equation (XII-1) as several kinds of acid salts are formed as the intermediary phases, which while being heated are ultimately converted into anhydrous sulphate. In order to simplify the problem we assume the existence of the acid sodium sulphate NaHS04 as the sole intermediary phase, so the total reaction (XII-1) can then be divided into two steps  

NaClw + HaS04r = NaHS04fl, + HC1W AH 9l = 0.79 kcal, (XII-2) NaClw + NaHS04W = NaaS04W + HC1W AH°9l = 14.89 kcal. (XII-3) 

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Mixing household cleansers can result in the production of hydrogen chloride gas, HCl(g). Not only is this gas dangerous in its own right, but it also reacts with oxygen to form chlorine gas and water vapour. 

Ethylene dichloride (EDC) is used to manufacture vinyl chloride monomer (VCM), which is one of the largest commodity chemicals produced in the world. EDC may be produced by the direct chlorination of ethylene or oxychlorination of ethylene in the presence of oxygen and hydrogen chloride. Pyrolysis of EDC produces VCM and an equal amount of hydrogen chloride as a co-product. This hydrogen chloride produced in the pyrolysis reactor is utilized by the oxychlorination process as one of the reactants. Therefore, the component processes of direct chlorination, EDC pyrolysis and oxychlorination are combined to develop a balanced process for the production of VCM with no net consumption or production of hydrogen chloride ... 

Dibutyl phthalate, also tritolyl phosphate or Silicone oils KF96 and DC703 (Dow Corning) as stationary phases with helium as the carrier gas have been used to separate silicon tetrachloride and phosphorus trichloride in trichlorosilane380,381. The esters vitiated results due to the production of hydrogen chloride by hydrolysis of the sample. 

In the benzoylation of anisole with BC, the copper(II) triflate/[bmim] [BFJ is recycled three times after washing with diethyl ether, affording the methoxy-substituted BPs in 86%, 79%, and 65% yield with an ortho/para ratio of 0.04 for all runs. The lowering of the catalyst efficiency is assumed to be due to the production of hydrogen chloride, possibly leading to the formation of an increasing amount of copper dichloride, which is inactive under these conditions. 

PVC undergoes dehydrochlorination (production of hydrogen chloride gas) under exposure to heat and light. The acidic gas corrodes metals in the vicinity. The reaction is autocatalytic. PVC becomes darker in colour as degradation progresses. Plasticizers are usually esters and undergo hydrolysis in acidic and basic environments to form white crystals of acid or anhydride. The PVC polymer is resistant to acids and bases. 

The reaction is strongly exothermic. Would an increase in temperature for the system tend to favor or disfavor the production of hydrogen chloride ... 

Detector tubes As with CO, hydrogen cyanide in air can be measured conveniently with reasonable accuracy by stain-length detector tubes. A typical reagent mixture is mercuric chloride and methyl red indicator. The hydrogen cyanide is converted to mercuric cyanide with the production of hydrogen chloride, which produces a pH change and as a result the indicator changes color to red ... 

Barium sulfate, as such or in the form of lithopones (BaS04 + ZnS, or + CdS) is used as pigment. It also constitues a weighting material in the manufacture of special papers. It can be easily detected in pigments or the ash of papers because it is completely converted into barium chloride by ignition with ammonium chloride. The conversion is due to the production of hydrogen chloride in the thermal decomposition of ammonium chloride and the gas is formed at about 400 C, in other words at a temper-... 

To a well-chilled solution of 122.5 gm (4 moles) of methylamine in 500 ml of dry benzene is added a solution of 176 gm (1.94 moles) of freshy distilled acrylyl chloride in 100 ml of benzene over a 2.75-hr period while a reaction temperature below 5°C is maintained. The solid which forms is filtered off. The filtrate is preserved. The solid is dissolved in water. The aqueous solution is extracted with two portions of benzene. The benzene extracts are combined with the filtrate. The benzene, excess amine, and water are removed from the product solution by distillation. The high-boiling residue is then fractionally distilled. The fraction boiling between 92° and 97°C (4-5 mm) is collected and redistilled at 79°C (0.7 mm). The yield is 107 gm (66% of theory), 1.4730. The product may be stored after inhibition with 0.1% of p-methoxyphenol. By-products are believed to be the addition products of hydrogen chloride or of methylamine to the double bond. 

Because of the comparatively high cost of chlorine and the simultaneous production of hydrogen chloride, the use of olefin feedstocks has become the preferred route to these materials. For that reason, the propylene tetramer was for many years the primary source of the alkyl group. When the change to linear alkylben-zenes occurred for reasons of improved biodegradability, straight-chain olefins were frequently used. 

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