Industrial processes Raschig process

Industrial preparation of hydrazine is based on this reaction of ammonia with an alkaline solution of sodium hypochlorite, known as the Raschig process introduced in 1907. 

Until the late 1890s, coumarin was obtained commercially only from natural sources by extraction from tonka beans. Synthetic methods of preparation and industrial manufacturing processes were developed starting principally from ortho-creso (Raschig process), phenol (Pechmann reaction) and salicylaldehyde (Perkin reaction). Various methods can be used to obtain coumarin from each of these starting materials. In order to be suitable for perfumery uses, synthetic coumarin must be highly pure (Bauer et al., 1988 Boisde Meuly, 1993). 

Fig. 22.26. Raschig process for hydrazine production. (Courtesy of Wiley-VCH. Schirmann, J.P, in Ullmann s Encyclopedia of Industrial Chemistry, Vol. A13, pp. 177-190, Reinhold Publishing, New York, 1996.)...

It is widely distributed in the plant kingdom, but most of it has been produced synthetically. Mostly used as a perfumery chemical in cosmetics and related industries, it is also used for a few industrial applications. The commercial synthesis of coumarin (by the Raschig process) is based on 113... 

These processes perform the oxidation of hydrochloric add in situ. Their principle is similar to the one implemented to produce phenol from benzene by the Hooker/Raschig process (see Section 10.1.3). The first industrial ethylene oxychlorination plant was built by Dow in the United States in 1955. 

Raschig process An industrial process for making chlorobenzene (and phenol) by a gas-phase reaction between benzene vapour, hydrogen chloride, and oxygen (air) at230°C... 

The industrial production of hydrazine (N2H4) by the Raschig process is the topic of the Focus On feature for Chapter 4 on www.masteringchemistry.com. The following chemical equation represents the overall process, which actually involves three consecutive reactions. 

The latter two methods are variants of the Hooker/Raschig and Dow processes, which are already industrialized. 

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