Acetylides from acetylenes

The preparation of lithium acetylides from acetylenes and butyl lithium can be carried out in THF at 20°. The lithium acetylides react with tellurium to form lithium ethynetellurolates. These tellurolates were reacted with chloroiodomethane at — 40° to — 60 to give the corresponding chloromethyl ethynyl telluriums11. Yields and physical properties of these latter products were not reported. 

Explosions involving flammable gases, vapours and dusts are discussed in Chapter 5. In addition, certain chemicals may explode as a result of violent self-reaction or decomposition when subjected to mechanical shock, friction, heat, light or catalytic contaminants. Substances containing the atomic groupings listed in Table 6.7 are known from experience to be thermodynamically unstable, or explosive. They include acetylides and acetylenic compounds, particular nitrogen compounds, e.g. azides and fulminates, peroxy compounds and vinyl compounds. These unstable moieties can be classified further as in Table 6.8 for peroxides. Table 6.9 lists a selection of potentially explosive compounds. 

Silver nitrate (or other soluble salt) reacts with acetylene in presence of ammonia to form silver acetylide, a sensitive and powerful detonator when dry. In the absence of ammonia, or when calcium acetylide is added to silver nitrate solution, explosive double salts of silver acetylide and silver nitrate are produced. Mercury(I) acetylide precipitates silver acetylide from the aqueous nitrate. 

Brameld et al(Ref 4) investigated the formation of copper acetylides from aq solus of various cupric salts and acetylene. The resulting compds appear to fall into two types a)black amors ppts and b)lustrous, metallic appearing plates... 

The precipitation of mercuric acetylide resulted in alkali consumption so that titrating the excess hydroxide gave a direct measure of the amount of acetylide and hence the concentration of acetylene in the gas mixture. The more usual method, precipitating silver acetylide from ammoniacal silver nitrate, was unsatisfactory in this case since the carbon monoxide in the product gases reduced the silver nitrate to silver. 

Sodium acetylide has also been prepared from acetylene and a sodium dispersion in an inert solvent at elevated temperatures [38]. This method seems more suitable for industrial application, since preparation of a sufficiently fine dispersion is not easily realized with the usual laboratory means. 

Higher homologues of acetylene can also be obtained from acetylene itself. Acetylene is converted into acetylide and the acetylide is reacted with alkyl halide to get a higher homologue. 

Alkali metal acetylides obtained from acetylenes and sodium in liquid ammonia1 react with tellurium powder to yield sodium ethynetellurolates that are easily alkylated with alkyl halides. 

The application box in the margin of page 401 states, The addition of an acetylide ion to a carbonyl group is used in the synthesis of ethchlorvynol, a drug used to cause drowsiness and induce sleep. Show how you would accomplish this synthesis from acetylene and a carbonyl compound. 

Acetylenic tertiary alcohols are prepared from sodium acetylides or acetylenic Grignard reagents and ketones in the same manner as described for primary and secondary alcohols (method 88). Dimethylethynylcarbinol is prepared from acetone, aqueous potassium hydroxide, and acetylene in an autoclave at 100° and 300 p.s.i. Ketones ate sometimes treated with an acetylide prepared from acetylene and a solution of sodium or potassium alkoxide in /-amyl alcohol. " Another procedure utilizes... 

This method finds commercial application in the production of acetaldehyde from acetylene. Mercuric salts in the presence of dilute sulfuric acid act as the catalyst. The reaction has been extended to higher alkylacetylenes, which are obtained in about 60% yield from sodium acetylide and alkyl halides. These compounds are readily hydrated in aqueous solutions of acetone, methanol, or acetic acid to give 80-90% yields of the corresponding methyl ketones, fot example, methyl butyl, methyl amyl, and methyl hexyl ketones. Hydration has been accomplished by passing the acetylenic hydrocarbon and steam over a phosphoric acid catalyst at 150-204° and atmospheric pressure. ... 

Oxidation of cuprous acetylides by air or potassium ferricyanide brings about the union of two acetylenic groupings as in the preparation of dimethyldiacetylene (42%).. The reaction has been applied to the synthesis of diynediols from acetylenic carbinols. ... 

Prepare the acetylide anion from acetylene by treatment with base. 

Step [3] B is prepared from acetylene and two 1 alkyl halides (C and D) by using Sn2 reactions with acetylide anions. 

Lithium acetylide is best prepared from acetylene and LiNH in liquid ammonia. Lithium acetylides are more soluble in liquid ammonia than sodium acetylides and therefore give higher yields (50-80%) on reaction with higher halides. trans-2-Alken-4-ynols have been generally obtained on alkylation of sodium acetylides with... 

Dilithium ethyneditellurolate was obtained in reactions of monolithium acetylide or of dilithium acetylide with tellurium in tetrahydrofuran containing 1,2-diaminoethane (DAE). The ditellurolate was reacted with methyl iodide to produce methyltelluroethynyl methyl telluride in good yields based on tellurium employed. The surprising formation of the ditellurolate from the monolithium acetylide was explained by the disproportionation of monolithium acetylide into dilithium acetylide and acetylene. ... 

In a trickle bed reactor the gas and liquid flow (trickle) concurrently downward over a packed bed of catalyst particles. Industrial trickle beds are typically 3 to 6 m deep and up to 3 m in diameter and are filled with catalyst particles ranging irom to in. in diameter. The pores of the catalyst are filled with liquid. In petroleum refining, pressures of 34 to 100 atm and temperatures of 350 to 425°C are not uncommon. A pilot-plant trickle bed reactor might be about 1 m deep and 4 cm in diameter. Trickle beds are used in such processes as the hydrodesulfurization of heavy oil stocks, the hydrotreating of lubricating oils, and reactions such as the production of butynediol from acetylene and aqueous formaldehyde over a copper acetylide catalyst. It is on this latter type of reaction,... 

Acetylene is a reactive material that poses a fire and explosion hazard. Its lower and upper explosive limits in air are 2.5% and 93%, respectively. Acetylene reacts with active metals (e.g., copper, silver, and mercury) to form explosive acetylide compounds. Acetylene manufactured from calcium carbide can contain impurities such as phosphine and arsine that are responsible for the ethereal to garlic-like odor of commercial acetylene and pose a greater human... 

Similar procedures are used with alkali acetylides, which are obtained from acetylenes and either sodium in ether or alkali in liquid ammonia.483-486... 

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