Mercuration acetylene derivs

Mercuric chloride, barium chloride-carbon a,/ -EthylenefIuorides from acetylene derivatives... 

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... 

Mercuric oxide sulfuric acid Ring closure with acetylene derivs. 0-Heterocydics... 

Mercuric oxide sulfuric acid Ketones from acetylene derivs. with formation of tetrahydropyrans from 5-aminoalcohols... 

Boron fluoride mercuric acetate Mercuration of acetylene derivs. Enol acetates s. 7, 201 suppl. 29... 

Mercuric acetate/sodium tetrahydridoborate Oxymercuration-demercuration s. 22, 143 improved yields with mercuric trifluoroacetate, Markownikoff monohydration of dienes, s. J. Org. Chem. 37, 1941 (1972) ketones from acetylene derivs. s. G. Chandra, D. Devaprabhakara, and M. S. Muthana, Current Sci. 40, 400 (1971)... 

Mercuric acetate/sodium tetrahydridoborate Addition of amines to acetylene derivs. 

Terminal alkyne anions are popular reagents for the acyl anion synthons (RCHjCO"). If this nucleophile is added to aldehydes or ketones, the triple bond remains. This can be con verted to an alkynemercury(II) complex with mercuric salts and is hydrated with water or acids to form ketones (M.M.T. Khan, 1974). The more substituted carbon atom of the al-kynes is converted preferentially into a carbonyl group. Highly substituted a-hydroxyketones are available by this method (J.A. Katzenellenbogen, 1973). Acetylene itself can react with two molecules of an aldehyde or a ketone (V. jager, 1977). Hydration then leads to 1,4-dihydroxy-2-butanones. The 1,4-diols tend to condense to tetrahydrofuran derivatives in the presence of acids. 

The hydration of acetylene produces acetaldehyde which then can be converted to acetic acid and other derivatives. The process is similar to olefin hydration employing a sulfuric acid solution containing also a mercurous sulfate catalyst. 

Hydrogen atoms adjacent to the triple bond of an acetylenic compd are easily replaced by silver, cuprous or mercurous atoms and the resulting metallic derivs are usually insol in w... 

Challenger and co-workers18,19,21,22 first used mercuration (HgClj) to isolate and purify the thienothiophenes from the reaction of acetylene with sulfur. Thieno[3,2-fc]thiophene gave a mixture of mercury derivatives with mercuric chloride both in the presence and in the absence of sodium acetate. The 2-monochloromercury derivative was isolated and converted to the corresponding acylthieno[3,2-h]thiophene with acetyl or propionyl chloride.21,218 The reaction of thienothiophene 2 with mercuric acetate affords the 2-acetoxymercury derivative.20... 

Contrary to the 1-vinylcyclopropanol derivatives which easily underwent an acid catalyzed or thermally induced C3 -> C4 ring expansion as discussed in Sect. 5.1.1, the acetylenic cyclopropanols 9 were surprisingly unreactive towards acids. Thus, on heating for two hours to 55 °C in acidic (0.75N HC1) 50 % aqueous dioxane containing a catalytic amount of mercuric chloride or upon treatment with m-chloroper-benzoic acid (MCPBA) for 12 hours at room temperature, the alcohol 9 (R = H) was recovered unchanged. However, treatment of 9 with an alcohol free solution of t-butylhypochlorite (t-BuOCl) in chloroform resulted in an exothermic reaction which yielded 2-chloromethylenecyclobutanone 39 as the only isolable product, Eq. (13)10). 

Here lies the first roadblock. Although the large scale preparation of some related vinyl derivatives such as enol ethers from acetylene itself has been used in the chemical industry for years, these syntheses usually require catalysis by mercuric salts and yields are often quite poor. Similarly, enamines have been claimed to be intermediates in the synthesis of amines from alkynes, but this process also requires mercuric ion catalysis. ... 

Vinylidenes have been transferred from a variety of precursors to olefins to produce methylenecyclopropanes . Because of ready intramolecular hydrogen shifts to give terminal acetylenes, the addition of vinylidene to olefins is rather limited to 2,2-disubstituted species. The methodologies so far developed include (1) gem-dibromides, 7, with MeLi, (2) vinyl halides " or vinyl triflates, 8 " with r-BuOK, (3) the fluoride ion promoted decomposition of vinylsilanes, 92 2,243 4 thermolysis of mercuric derivatives, 10, at 250 (5) decomposition of vinylazo compounds, 11, at 25 (6) the alkaline... 

Ketone derivatives whose oxidations have wide applications in synthesis are hydrazones and vicinal dihydrazones. Hydrazones are transformed into diazo compounds, and vicinal dihydrazones are converted into acetylenes. By far the most widely used oxidant is yellow mercuric oxide... 

Derivation Reaction of acetylene with aqueous solution of mercurous salts. 

Ethylidene derivatives of alditols have been made by treatment of an alditol with acetylene in the presence of sulfuric acid and mercuric sulfate 166), Apparently the intermediate vinyl hydroxyethyl ether is formed which then condenses with a second hydroxyl group. 

Acetylenic groups react with 2 moies of mercuric acetate to form adducts, but the originai bonds cannot be regenerated and a keto derivative is formed on acidic hydroiysis. This reaction has been turned to advantage to iocate the position of the original triple bond in a fatty acid derivative by mass spectrometry [140,480],... 

Triacetylenic boranes are derived from lithium acetylides and boron trifluoride etherate in THF at —20 °C. They react with ethyl diazoacetate to give homologated propargyl esters (7) after hydrolysis. Hydration of these iSy-acetylenic esters using mercuric ion is regiospecific only y-keto-esters (8)... 

Various compounds have been obtained by the reaction between acetylenes and solutions of mercuric salts. Thus crystalline derivatives RC=C—Hg—C=CR are obtained from mercuric oxide and RC=CH. Crystalline substances RHgC=CHgR result when RHgX reacts with acetylene itself in alcoholic potassium hydroxide. An important property of these compounds is their ready hydrolysis to aldehydes. It is probable that hydration of acetylene to acetaldehyde (industrially important some years ago) proceeds though such intermediates. 

Equimolar quantities of acetylenedicarboxylic acid esters (166) and 2-N-substituted l,3-dithiolan-2-imines (169) undergo a 1,3-dipolar cycloaddition, with elimination of ethylene, to yield A -thiazoline-2-thiones (168). The same products result from 2-alkylthio-l,3,4-thiadiazoline-5-thiones (167), with loss of alkyl thiocyanate as shown. They are desulphurized to the corresponding thiazolinones (172) by the action of mercuric acetate in acetone-acetic acid. They react with two further moles of the acetylenic reagent (166) to produce the spiranes (170 e.g. = R = COzMe), which are in turn desulphurized and cleaved by Raney nickel to the AMhiazoline derivatives (171). An analogous series of reactions was carried out using propiolic acid esters. ... 

---