Bechamp

Bechamp batch process Bechamp reaction Beck and Guthke cell Becke line technique... 

The reduction of the nitro group to yield aniline is the most commercially important reaction of nitrobenzene. Usually the reaction is carried out by the catalytic hydrogenation of nitrobenzene, either in the gas phase or in solution, or by using iron borings and dilute hydrochloric acid (the Bechamp process). Depending on the conditions, the reduction of nitrobenzene can lead to a variety of products. The series of reduction products is shown in Figure 1 (see Amines byreduction). Nitrosobenzene, /V-pbenylbydroxylamine, and aniline are primary reduction products. Azoxybenzene is formed by the condensation of nitrosobenzene and /V-pbenylbydroxylamine in alkaline solutions, and azoxybenzene can be reduced to form azobenzene and hydrazobenzene. The reduction products of nitrobenzene under various conditions ate given in Table 2. 

The Faux process is a modification of the Bechamp reaction that was discovered in 1854. It has been used for the reduction of nitrobenzene to aniline using metallic iron ... 

The old Bechamp batch process for reduction of nitroben2ene (iron-hydrochloric acid) is obsolete however, Mobay Chemical Corporation is operating a plant using this process for production of pigment grade iron oxide as weU as aniline. 

In general As " organic derivatives are more toxic than As derivatives. The use of organoarsenicals in medicine dates from the discovery in 1905 by H. W. Thomas that atoxyl (first made by A. Bechamp in 1863) cured experimental trypanosomiasis (e.g. sleeping sickness). In 1907 P. Erlich and A. Bertheim showed that atoxyl was sodium hydrogen 4-aminophenylarsonate... 

It is worth noting, however, that up until fairly recently the reduction of aromatic nitrocompounds to the corresponding amines was commonly performed on an industrial scale, e.g. in the synthesis of azo dyes, with a mixture of iron and hydrochloric acid. This so-called Bechamp reduction has an E factor of ca. 15 compared to 1 for catalytic hydrogenation. 

Bechamp A process for reducing organic nitro-compounds to amines, using iron, ferrous salts, and acetic acid. Invented by A. J. Bechamp in 1854 and still used for making certain aromatic amines. 

C6H5N02 + 9Fe + 4H20 = 4C6H5NH2 + 3Fe304 Invented in 1926 by J. Laux at Bayer and used commercially thereafter. It was an improvement on the Bechamp process. 

Anhydrous sodium tungstate, 25 382 Anhydrous stannic chloride, 24 803 Anhydrous stannous chloride, 24 802-803 Anhydrous zinc chloride, 26 617 Anhydrous zinc sulfate, 26 617 Aniline, 2 783-809, 17 250, 259 alkylation, 2 197 Bechamp process, 2 490 from benzene, 3 619t, 620 chemical reactions, 2 783-789 derivatives, 2 783-809 economic aspects, 2 790-791... 

The traditional technique of reducing nitro compounds with iron powder in dilute acid (Bechamps-Brimmeyr reduction) continues to be used for nitro compounds that are adversely affected by the catalytic reduction method with hydrogen. The list of examples includes aromatic nitro compounds carrying halogen substituents, especially if these are attached in ortho or para position to the nitro group. The solution containing only a small amount of acid (such as acetic acid) is almost neutral and allows iron to precipitate as Fe304. 

The property of being converted by energetic reduction into primary amines belongs to the nitro-compounds both of the aliphatic and of the aromatic series. Six atoms of hydrogen are required for the reduction of each nitro-group. In industry nitrobenzene is reduced, not with expensive tin, but with iron filings or iron powder according to the old method of Bechamp, which is still in use at the present time. The amount of hydrochloric acid indicated by the equation... 

Bechamp reduction org chem Reduction of nitro groups to amino groups by the use of ferrous saits or iron and dilute acid. ba shan ri dok-shon ... 

Baeyer-Villiger reaction, 9, 3 43, 3 Bamford-Stevens reaction, 23, 3 Barbier Reaction, 58, 2 Bart reaction, 2, 10 Barton fragmentation reaction, 48, 2 Bechamp reaction, 2, 10 Beckmann rearrangement, 11, 1 35, 1 Benzils, reduction of, 4, 5 Benzoin condensation, 4, 5 Benzoquinones ... 

Laux Process. This is a modification of the Bechamp process for the iron reduction of nitrobenzene to aniline which leaves iron oxide as the residue. Incorporation of iron or aluminium chlorides into the reduction process produces high quality yellow and red iron oxide pigments... 

Berthelot, M. (1857) Ueber die geistige Gahrang. J. Praktische Chemie, 71,321-325. Berthelot, M. (1864) Remarques sur la note de M.Bechamp relative a la fermentation alcoolique. Bulletin Soc. Chim. 392-393. 

Arsanilic acid was prepared by Bechamp 1 by heating aniline arsenate to 190-200°. The product was originally described as the anilide of arsenic acid, but Ehrlich and Bertheim 2 showed its structure to be that of a true aryl arsenic acid. 

The process of reduction of nitrocompds was discovered in 1842 by N,Zinin, a prof at the Univ of Kazan, Russia. He prepd aniline by reducing nitrobenzene with (NH )2S. A less expensive reducing agent, Fe and dil acid, was proposed in 1854 by Bechamp. The reduction process by Fe and acid was used on a large scale by Perkin. With cheap aniline the synthetic dyestuff industry was born... 

Most of these products have been detected by the earliest investigators of nitrocellulose, such as Vohl [43], Bechamp [44], Hadow [45], Will [46] and M. Bert-helot [47]. 

The problem of how to stabilize nitrostarch has been solved by different means, but the majority of stabilization processes remain obscure as patent secrets. None the less, from certain observation some general conclusions can be made. It was early observed by Bechamp [13] that nitrostarch obtained by nitration in nitric acid alone is more stable than one obtained by means of nitric acid mixed with sulphuric acid. This has been confirmed experimentally by Hackel and T. Urbanski [18], and seems likely to be explained by the formation of starch sulphates or mixed nitric and sulphuric esters of starch. 

---