Mercury salt anhydride

Manufacture and Processing. Until World War II, phthaUc acid and, later, phthaUc anhydride, were manufactured primarily by Hquid-phase oxidation of suitable feedstocks. The favored method was BASF s oxidation of naphthalene [91-20-3] by sulfuric acid ia the presence of mercury salts to form the anhydride. This process was patented ia 1896. During World War I, a process to make phthaUc anhydride by the oxidation of naphthalene ia the vapor phase over a vanadium and molybdenum oxide catalyst was developed ia the United States (5). Essentially the same process was developed iadependendy ia Germany, with U.S. patents being granted ia 1930 and 1934 (6,7). 

Strong dehydrating agents such as phosphorous pentoxide or sulfur trioxide convert chlorosulfuric acid to its anhydride, pyrosulfuryl chloride [7791-27-7] S20 Cl2. Analogous trisulfuryl compounds have been identified in mixtures with sulfur trioxide (3,19). When boiled in the presence of mercury salts or other catalysts, chlorosulfuric acid decomposes quantitatively to sulfuryl chloride and sulfuric acid. The reverse reaction has been claimed as a preparative method (20), but it appears to proceed only under special conditions. Noncatalytic decomposition at temperatures at and above the boiling point also generates sulfuryl chloride, chlorine, sulfur dioxide, and other compounds. 

Mercury salts, such as mercury(II) acetate,521-525 mercury(II) oxide,524,526-528 metcury(II) trifluoroace-tate,529,530 mercury(II) sulfate524,531 and mercury(II) phosphate531 catalyze the addition of carboxylic acids to alkynes. Acetic anhydride in the presence of boron trifluoride etherate can also be effectively used in this reaction (equation 292).521,522 Alkynoic acids undergo mercury-catalyzed cyclization to lactones (equation 293).523,532,533... 

The manufacture of phthalic anhydride (world installed capacity ca. 4.4 Mt/a) has several points of similarity to that of maleic anhydride in that there are two alternative feedstocks and a large amount of heat is released. The first process, introduced by BASF at the end of 19 century, was based on the liquid phase oxidation of naphthalene catalyzed by mercury salts. It was later replaced by the cleaner gas phase process, carried out over vanadium and molybdenum oxides. Naphthalene was supplied by coal tar distillation and was used exclusively until the end of 1950s when u-xylene, of petrochemical origin, became an abundantly available feedstock (Equation 36). A few production units however can use either feedstock, taking advantage of price fluctuations in coke plants (naphthalene) and in refineries (u-xylene). 

Sulfophthalic anhydride is formed on sulfonation of phthalic anhydride by oleum, but presence of mercury(i) sulfate leads to the 3,5-disulfonic acid.162 The catalytic effect of mercury and mercury salts is also applied to the conversion of 4-methylpyridine into 4-methyl-3-pyridinesulfonic acid163 and of... 

Fuming sulfuric acid, H2SO4 + SO3, in the presence of mercury salts is a powerful oxidizing agent. It was formerly used extensively in this way for the oxidation pf naphthalene to phthalic anhydride but has been displaced in this operation by the newer air-oxidation processes. 

By altering the reaction conditions, a preponderance of either product may be produced as desired. Vinyl acetate, which is used for making polymers, and ethylidene diacetate, which is an intermediate for the manufacture of acetic anhydride, are produced on a large scale. The reaction may be applied to other carboxylic adds and acetylene derivatives. Strong acids, such as sulfuric, methane di- and trisulfonic, and phosphoric acids, are catalysts. They may be used in conjunction with mercury salts. Other catalysts which have been disclosed for the reaction include boron trifiuoride and the salts of various metals, such as zinc silicate, zinc acetate, and mercuric phosphate. The addition may be effected in the vapor phase... 

According to Bagal [2], the sodium salt forms a pentahydrate at room temperature that loses two molecules of crystalline water above 30 °C and forms an anhydride salt above 75 °C. Contrary to other authors, Reddy and Chatterjee [90] have reported the formation of a monohydrate for the sodium and barium salts (on the basis of TGA results). Lead and mercury salts form as anhydrides [90]. 

According to Reddy and Chatteijee, sodium and barium monohydrates are not sensitive to fiiction and impact under the conditirms generally used for primary explosives, whereas lead and mercury salts are highly sensitive to both [90], In the Fedoroff, Sheffield, and Kaye s encyclopedia, it is however mentioned that sensitivity of the sodium, potassium, and barium salts is mily about twice as high as for lead azide (not specified if the values concern anhydride or hydrates) [1],... 

A common synthetic method is that of equation (9), where X = MeC02,168 PhS03,169 NO3170 or C104,171 and relies on the precipitation of silver chloride. A variation of this method is the synthesis of the ring complex (5), by the reaction (10).172 In other cases, the synthesis may involve mercury(II) salts or sodium salts (equations 11 and 12).173,174 Another useful synthetic method involves reaction of alkyl- or aryl-gold(I) complexes with carboxylic acids or acid anhydrides (equations 13-15).176,177... 

Dihalofuroxans are formed on dehydrohalogenation of dihaloximes and when halogens react with mercury or silver fulminates. Iodine with the silver salt of phenylnitrosolic acid gives diphenylfuroxan. Boron trifluoride in acetic anhydride reacts with 2-(ethoxycarbonyl-nitromethylene)thiazolidine to give diethoxycarbonyl furoxan. In each case nitrile oxides are likely or proven intermediates. 

Chloromercurithiophene or mercury 2 2 -dithienyl is treated with arsenious chloride and the product warmed on the water-bath. The filtrate from this mixture is treated with aqueous sodium hydroxide, then with hydrogen peroxide. Addition of barium chloride then helps to remove any inorganic arsenic which has not crystallised out as sodium arsenate. The whole is filtered, the filtrate freed from barium and sulphuric acid and evaporated down after the addition of concentrated hydrochloric acid. The residue is dissolved in alcohol, boiled with charcoal, and treated with sodium hydroxide. The sodium salt of the arsinic acid crystallises out in transparent, colourless, non-deliquescent, rhombic plates, which are very soluble in water. The free acid forms tufts of needles, M.pt. 185 5° C., fairly soluble in water or alcohol. At 106° to 108° C. it is converted into the corresponding anhydride. Sulphurous acid in the presence of a trace of hydriodic acid reduces it to thienyl-2-arsenoxide, whilst with sodium hydrosulphite it yields 2 2 -arsenothiophe-ne,... 

When heated at 150° C. phenylmercuric acetate gives carbon, benzene, mercury, oxygen, and acetic anhydride. Dry distillation yields mercury, diphenyl oxide, and acetic anhydride. Distillation with sulphur gives mercury, benzene, acetic acid, acetic anhydride, and diphenyl sulphide. Boiling with dilute sulphuric or hydrochloric acid produces benzene, acetic acid, and a mercuric salt. The acetate is reduced by nascent hydrogen to benzene, mercury, and acetic acid. 

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