[9] Pure acetylene is odorless, but commercial grades usually have a marked odor due to impurities such as divinyl sulfide and phosphine.

[14] Berthelot's empirical formula for acetylene (C4H2), as well as the alternative name "quadricarbure d'hydrogène" (hydrogen quadricarbide), were incorrect because many chemists at that time used the wrong atomic mass for carbon (6 instead of 12).

[20] The heaviest alkanes in petroleum and natural gas are cracked into lighter molecules which are dehydrogenated at high temperature: This last reaction is implemented in the process of anaerobic decomposition of methane by microwave plasma.

[22] Acetylene was historically produced by hydrolysis (reaction with water) of calcium carbide: This reaction was discovered by Friedrich Wöhler in 1862,[23] but a suitable commercial scale production method which allowed acetylene to be put into wider scale use was not found until 1892 by the Canadian inventor Thomas Willson while searching for a viable commercial production method for aluminum.

[24] As late as the early 21st century, China, Japan, and Eastern Europe produced acetylene primarily by this method.

In the US, this process was an important part of the late-19th century revolution in chemistry enabled by the massive hydroelectric power project at Niagara Falls.

On the other hand, oxy-acetylene welding equipment is quite versatile – not only because the torch is preferred for some sorts of iron or steel welding (as in certain artistic applications), but also because it lends itself easily to brazing, braze-welding, metal heating (for annealing or tempering, bending or forming), the loosening of corroded nuts and bolts, and other applications.

Bell Canada cable-repair technicians still use portable acetylene-fuelled torch kits as a soldering tool for sealing lead sleeve splices in manholes and in some aerial locations.

For use in welding and cutting, the working pressures must be controlled by a regulator, since above 15 psi (100 kPa), if subjected to a shockwave (caused, for example, by a flashback), acetylene decomposes explosively into hydrogen and carbon.

[38] In 1881, the Russian chemist Mikhail Kucherov[39] described the hydration of acetylene to acetaldehyde using catalysts such as mercury(II) bromide.

The carbide can then be reacted with water, as usual, to form acetylene gas to feed into a mass spectrometer to measure the isotopic ratio of carbon-14 to carbon-12.

[47] In most of these applications, direct combustion is a fire hazard, and so acetylene has been replaced, first by incandescent lighting and many years later by low-power/high-lumen LEDs.

Nevertheless, acetylene lamps remain in limited use in remote or otherwise inaccessible areas and in countries with a weak or unreliable central electric grid.

[47] The energy richness of the C≡C triple bond and the rather high solubility of acetylene in water make it a suitable substrate for bacteria, provided an adequate source is available.

Since such temperatures are highly unlikely on such a small distant body, this discovery is potentially suggestive of catalytic reactions within that moon, making it a promising site to search for prebiotic chemistry.

A similar situation applies to the conversion of acetylene to the valuable vinyl chloride by hydrochlorination vs the oxychlorination of ethylene.

These complexes are intermediates in many catalytic reactions such as alkyne trimerisation to benzene, tetramerization to cyclooctatetraene,[9] and carbonylation to hydroquinone:[54] Metal acetylides, species of the formula LnM−C2R, are also common.

Its most singular hazard is associated with its intrinsic instability, especially when it is pressurized: under certain conditions acetylene can react in an exothermic addition-type reaction to form a number of products, typically benzene and/or vinylacetylene, possibly in addition to carbon and hydrogen.

[citation needed] Consequently, acetylene, if initiated by intense heat or a shockwave, can decompose explosively if the absolute pressure of the gas exceeds about 200 kilopascals (29 psi).

[58][59] It is therefore supplied and stored dissolved in acetone or dimethylformamide (DMF),[59][60][61] contained in a gas cylinder with a porous filling, which renders it safe to transport and use, given proper handling.

[62] Information on safe storage of acetylene in upright cylinders is provided by the OSHA,[63][64] Compressed Gas Association,[59] United States Mine Safety and Health Administration (MSHA),[65] EIGA,[62] and other agencies.

[59][64] Acetylene cylinders should not be stored in confined spaces, enclosed vehicles, garages, and buildings, to avoid unintended leakage leading to explosive atmosphere.

[59][64] In the US, National Electric Code (NEC) requires consideration for hazardous areas including those where acetylene may be released during accidents or leaks.

[68] In Europe, ATEX also requires consideration for hazardous areas where flammable gases may be released during accidents or leaks.