(US5274149-A)      Continuous prodn. of alkylarsines comprises (a) continuously contacting an olefin and arsine in vapour phase over a Bronsted acid in a reaction vessel: (b) condensing the prod; and (c) removing it from the vessel.    Opt. olefin and arsine are recycled for a second pass over the catalyst. Prod. is opt. purified by distn.    USE -   In prods. of mono-tert. butylarsine. contg. no metallic or oxygenating impurities, for mfr. of solar cells and computer chips.    (US5415129-A)      As-contg semiconductor particles are produced by continuously contacting, in the vapour phase, an olefin and AsH3 over a Bronsted Acid catalyst to produce an alkylarsine, then using this alkylarsine as the As source during MOCVD. The alkylarsine is pref mono-t-butyl arsine, and is purified by distn before use.    ADVANTAGE -   Continuous alkylarsine prodn. High quality semiconductors can be produced.    (EP560029-B1)      Prepn. of alkylarsines comprises contacting an olefin and arsine in the presence of a Bronsted acid catalyst. Reaction takes place in the vapour phase.    Also claimed are: (1) a continuous process in which the olefin and arsine are contacted in presence of the catalyst in a reaction vessel, condensing and removing the resultant prod.; and (2) prepn. of arsenic-contg. semiconductor articles by conducting metal organic chemical vapour deposition (MOCVD) in which process the alkylarsines formed are used as the volatile source of arsenic.    USE/ADVANTAGE -   Mono-alkylarsines and esp. mono-tert.-butylarsine are used in semiconductor applications such as solar cells and computer chips. Mono-tert.-butylarsine can be used to make galluim arsenide thin films by MOCVD, with an increased yield of arsenide based on arsenic use. High purity mono-arsines are prepd. which contain little sulphur, germanium, metallic or oxygenating impurities i.e. less than 1ppm. The process is highly selective and produces a high yield of prod. of good i.e. in excess of 90 wt.percent. High reaction (arsine) pressures are not required, nor is the disposal of significant quantities of reactants and/or by prods. such as dialkylarsine. Lengthy purificn. is not necessary.