Hydrogenation mercury salts

Acetoiicetyliition Reactions. The best known and commercially most important reaction of diketene is the aceto acetylation of nucleophiles to give derivatives of acetoacetic acid (Fig. 2) (1,5,6). A wide variety of substances with acidic hydrogens can be acetoacetylated. This includes alcohols, amines, phenols, thiols, carboxyHc acids, amides, ureas, thioureas, urethanes, and sulfonamides. Where more than one functional group is present, ring closure often follows aceto acetylation, giving access to a variety of heterocycHc compounds. These reactions often require catalysts in the form of tertiary amines, acids, and mercury salts. Acetoacetate esters and acetoacetamides are the most important industrial intermediates prepared from diketene. 

An alternative route to the reaction of mercuric fluoride with fluoroolefins in liquid hydrogen fluoride [154] was developed during the early and middle 1970s This improved method involved the reaction of fluoroolefins and mercury salts in the presence of alkali metal fluorides m aprotic solvents [i5J, 156] (equation 118)... 

To operate the above process for the manufacture of hydrogen it is necessary that the aluminium should be as pure as possible and should not contain copper. The commercial light alloy known as "duralumin, which contains about 94 per cent, of aluminium and 4 per cent, of copper, is entirely unsuitable for generating hydrogen in the method above described, as it is almost unattacked by even boiling water containing a small quantity of a mercury salt... 

The action of 1% methanolic hydrogen chloride on 1,2-O-iso-propylidene -3,5-di - O - p-tolylsulfonyl-D-xylofuranose (65) leads,81 after boiling for three hours under reflux, to 2,5-anhydro-3-0-p-tolylsulfonyl-D-xylose dimethyl acetal (66). The structure of 66 was demonstrated by conversion into the disulfonate 67 this was prepared independently from a 2,5-anhydro-D-xylose dialkyl dithio-acetal72 (48) by p-toluenesulfonylation followed by exchange of the acetal group in methanol in the presence of mercury salts. 

Mercuric cyanide, when heated strongly in the absence of air, yields cyanogen (CN)2 and mercury. The salt is only slightly dissociated in water and yields no precipitate of mercury salt with any reagent except hydrogen sulfide. 

The most widely used mercury salts for this transformation are Hg(OAc)2 in the presence of catalytic amounts of HCIO4375 or Hg(02CCFj)2.376 While hydrogen peroxide itself can be used, mono- and di-mercuration products have been observed.377 Alkyl hydroperoxides generally give cleaner reactions. Di-chloromethane is commonly employed as the solvent. 

For reductions, hanging mercury drop electrodes or mercuryfilm electrodes are frequently used owing to their microscopic smoothness and because of the large overpotential for hydrogen evolution characteristic for this electrode material. Mercury film electrodes are conveniently prepared by the electrochemical deposition of mercury on a platinum electrode from an acidic solution of an Hg2+ salt, e.g. the nitrate. However, the oxidation of mercury metal to mercury salts or organomercurials at a low potential, 0.3-0.4 V versus the saturated calomel electrode (SCE), prevents the use of these electrodes for oxidations. 

The addition of water to alkynes is also aided by the presence of mercury (II) salts. The reaction is usually conducted in water, with the presence of a strong acid, such as sulfuric acid, and a mercury salt, such as HgS04 oi HgO. In this case the mercury is spontaneously replaced by hydrogen under the reaction conditions, so a second step is not necessary. The addition occurs with a Markovnikov orientation stereochemistry is not an issue. 

Cases might arise, in the sterilization by copper or mercury salts, where this restoring action of hydrogen sulphide would be troublesome. HjS is not usually suspected of being a revivifying agent 1... 

Catalytic conversions were experimentally studied in Russia toward the end of the nineteenth century, and especially in the twentieth century, and regularities were empirically established in a number of cases. The work of A. M. Butlerov (1878) on polymerization of olefins with sulfuric acid and boron trifluoride, hydration of acetylene to acetaldehyde over mercury salts by M. G. Kucherov (1881) and a number of catalytic reactions described by V. N. Ipatieff beginning with the turn of the century (139b) are widely known examples. S. V. Lebedev studied hydrogenation of olefins and polymerization of diolefins during the period 1908-13. Soon after World War I he developed a process for the conversion of ethanol to butadiene which is commercially used in Russia. This process has been cited as the first example of commercial application of a double catalyst. Lebedev also developed a method for the polymerization of butadiene to synthetic rubber over sodium as a catalyst. Other Russian chemists (I. A. Kondakov I. Ostromyslenskif) were previously or simultaneously active in rubber synthesis. Lebedev s students are now continuing research on catalytic formation of dienes. 

Mercury salts can react directly with hydrocarbons exchanging hydrogen for mercury. This reaction is an electrophilic substitution (equation 5) and hence can take place with arenes, cyclopentadienyls, terminal aUcynes, and also with aliphatic hydrocarbons that contain activated carbon-hydrogen bonds (e.g. carbonyl or nitrile compoimds). When the hydrocarbon contains several equivalent hydrogen atoms, polymercuration is often observed. 

Acetylene is condensed to vinylacetylene and divinylacetylene by cuprous chloride and ammonium chloride. Similar additions of other compounds containing an active hydrogen atom occur in the presence of various catalysts. Mercury salts ate most effective in the vapor-phase reaction of acetylene with hydrogen chloride to give vinyl chloride (100%). Basic catalysts such as potassium hydroxide, potassium ethoxide, or zinc oxide are used for the vinylation of alcohols, glycols, amines, and acids. Most of these reactions involve the use of acetylene under pressure, and few have been described as simple laboratory procedures. Chloroacetic acid, however, reacts with acetylene at atmospheric pressure in the presence of mercuric oxide to yield vinyl chloro-acetate (49%). ... 

Care must be taken in carrying out this test tliat alcohol and ether, should they be present, do not prevent the luminescence of the vapours. Turpentine and other volatile oils, as well as phenol and creosote, often completely prevent it furthermore, red phosphorus does not produce this luminescence, but mixtures of sulphur and phosphorus, such as are found in match-heads, will cause it. According to Polstorff and Mensching, the luminescence is also hindered by the presence of mercury salts. Copper salts and sulphuretted hydrogen also said to interfere. Even after continued distillation, the whole of the phosphorus will not be found in the distillate O. Schifferdecker calculates that for ev cry milligram of phosphorus in the distillate, the original substance contained 1 5 to 2 0 mg. 

Derivation Bypassing hydrogen sulfide into a solution of mercury salt, reaction of mercury with sulfur. 

---