Welding welding was invented in 1893, and around that time another process, oxyfuel welding, became well established. Acetylene was discovered in 1836 by Edmund Davy, but its use was not practical in welding until about 1900, when a suitable torch was developed. At first, oxyfuel welding was one of the more popular welding methods due to its portability and relatively low cost. As the 20th century progressed, however, it fell out of favor for industrial applications. It was largely replaced with arc welding, as advances in metal coverings (known as flux) were made. Flux covering the electrode primarily shields the base
Acetylene situation applies to the conversion of acetylene to the valuable vinyl chloride by hydrochlorination vs the oxychlorination of ethylene. Acetylene adds to ketones and aldehydes in the presence of base catalysts. Formaldehyde gives sequentially propargyl alcohol and butynediol. Since acetylene has a pK of 25, acetylene can be deprotonated by a superbase to form an acetylide: Various organometallic and inorganic reagents are effective. The formation of the acetylide depends upon several factors such as the pK of the base, the valency of the metal, and solvent characteristics. Copper(I) acetylide and silver acetylide can be formed in aqueous solutions with ease