Gattermann method

Bart Reaction Borsche (Cinnoline) Synthesis Demianov Rearranement Diazo Reaction Gattermann Reaction Gattermann Method Pschorr Arvlation Sandmever Reaction Schiemann Reaction (Bak-Schiemann JRxn) Tiffeneau-Demianov Reaction fVidman-Stoermer ([Pg.847]

This reaction was initially reported by Gattermann in 1890. It is the preparation of aromatic halides or aromatic cyanides by decomposition of corresponding diazo salts in the presence of copper powder, in which copper powder is freshly obtained from a copper (II) sulfate aqueous solution. Therefore, it is generally known as the Gattermann reaction. Occasionally, it is also referred to as the Gattermann method. It should be pointed out that this reaction is almost equivalent to the Sandmeyer Reaction It is believed that a radical mechanism might be involved in this reaction, by which electron transfer occurs at the surface of metallic copper. However, this reaction is not applicable for the preparation of aromatic fluorides because HF exists as H2F2 and ionized as H+ and 10 2 . ... 

Zinc cyanide. Solutions of the reactants are prepared by dis solving 100 g. of technical sodium cyanide (97-98 per cent. NaCN) in 125 ml. of water and 150 g. of anhydrous zinc chloride in the minimum volume of 50 per cent, alcohol (1). The sodium cyanide solution is added rapidly, with agitation, to the zinc chloride solution. The precipitated zinc cyanide is filtered off at the pump, drained well, washed with alcohol and then with ether. It is dried in a desiccator or in an air bath at 50°, and preserved in a tightly stoppered bottle. The yield is almost quantitative and the zinc cyanide has a purity of 95-98 per cent. (2). It has been stated that highly purified zinc cyanide does not react in the Adams modification of the Gattermann reaction (compare Section IV,12l). The product, prepared by the above method is, however, highly satisfactory. Commercial zinc cyanide may also be used. 

The yields by the Gattermann reaction are usually not as high as those by Sandmeyer s method. Copper powder is also employed in the preparation of sulphinlc acids, for example ... 

Gattermann s Method.— Accoiding to this method the diazonium bromide is first picparcd and then decomposed by finely divided metallic copper. The 50 grams /-toluidine is dissohed in 200 c.c. liydrobromic acid previously diluted with too c.c. water and diazoliscd in the usual way. To this solution... 

It has also been stated that the 5-position of selenazoles is more reactive toward electrophilic substitution than that of thiazoles. Such reactivity is still further increased by substituents in the 2-position of the selenazole ring, which can have an —E-effect. Simultaneously, however, an increasing tendency toward ring fission was observed by Haginiwa. Reactions of the selenazole ring are thus limited mainly to the 5-position which, specially in the 2-amino-and the 2-hydrazino-selenazoles, is easily substituted by electrophilic reagents. However, all attempts to synthesize selenazole derivatives by the Gattermann and by the Friedel-Crafts methods... 

The reaction of arenediazonium ions with hydroxylamine is known, but has been little investigated (Gattermann and Ebert, 1916). The l-aryl-3-hydroxytriazene (6.23) formed initially is in most cases unstable (except if Ar = anthraquinonyl). Under alkaline conditions elimination of N20 yields the amine, whereas the aryl azide is formed in the presence of acid (Scheme 6-15). There are, however, better methods for the synthesis of aryl azides (review Biffin et al., 1971, p. 147). 

Gattermann, Laboratory Methods of Organic Chemistry, p. 268, The Macmillan Company, New York, 1934. 

For preparative purposes the method of obtaining aldehydes from the primary alcohols is preferable by far, at least in the aliphatic series. The simple aromatic aldehydes can be obtained by alkaline hydrolysis of the arylidene chlorides, R.CHC12, which are produced from the hydrocarbons by substitution with chlorine (technical method for the preparation of benzaldehyde). In addition to these methods the elegant synthesis of Gattermann and Koch should be mentioned here. This synthesis, which proceeds like that of Friedel-Crafts, consists in acting on the aromatic hydrocarbon with carbon monoxide and hydrogen chloride in the presence of aluminium chloride and cuprous chloride. 

While the student is being educated in preparative work it is necessary for him to acquire some knowledge of the incessant progress in the methods of organic chemistry and at the same time to become familiar with the most recent results of research work. For these reasons a series of changes had to be made when this new edition was prepared. In order not to increase the bulk of the book these objects have been attained by sacrificing examples (e.g. lino-lenic acid, crystal violet, Gattermann-Koch aldehyde synthesis) with which, from this point of view, it seemed possible to dispense. 

The only formic acid derivative that allows the direct formylation of aromatics is formyl fluoride1617 since others (halides and the anhydride) that could be used in Friedel-Crafts-type acylations are quite unstable. Other related methods, however, are available to transform aromatic hydrocarbons to the corresponding aldehydes. The most frequently used such formylations are the Gattermann-Koch reaction16 17 and the Gattermann synthesis.10 16 17... 

Other Formylations. Formyl fluoride, the only known stable formic acid derivative, can be used to perform Friedel-Crafts-type acylation to form aromatic aldehydes. The method was developed by Olah and Kuhn.105 Although a number of Lewis acids may be used, BF3 is the best catalyst. It is dissolved in the aromatic compound to be formylated then formyl fluoride is introduced at low temperature and the reaction mixture is allowed to warm up to room temperature. The aldehydes of benzene, methylbenzenes, and naphthalene were isolated in 56-78% yields. Selectivities are similar to those in the Gattermann synthesis ( toiuene benzene = 34.6, 53.2% para isomer). The reacting electrophile was suggested to be the activated HCOF BF3 complex and not the free formyl cation. Clearly there is close relationship with the discussed CO—HF—BF3 system. 

Benzoyl azide is extremely sensitive to impact or friction, exploding even when pressed with a glass rod. The crude prod expl at ca 150° and its sensitivity is increased by small amounts of impurities or by confinement. Bergel(Ref 3) described two explns which took place during its prepn by the Gattermann-Wieland method from ethylbenzo-ate... 

The zinc dust must be analyzed (Gattermann, Practical Methods of Organic Chemistry, 3rd ed., p. 390), and a proportional quantity used if the zinc content is not 85 per cent. Technical nitrobenzene is satisfactory if it distils over a range of not more than 5 degrees and is not acid in reaction. 

Reaction XLIX. (b) Action of finely divided Copper and Alkali Cyanides on Aromatic Diazonium Compounds (Gattermann). (B., 23, 1218.)—This is the Gattermann modification of the preceding Sandmeyer reaction as usual, the cuprous salt is replaced by finely divided copper. This method gives better yields of some aromatic nitriles. 

Among the most frequently used formylation methods, the Gattermann-Koch reaction shows the highest selectivity reflected both in the observed high toluene- benzene rate ratios as well as a high degree of para substitution (Table 5.30). 

The yield is almost quantitative and the zinc cyanide has a purity of 95-98 per cent. It has been stated that highly purified zinc cyanide does not react in the Adams modification of the Gattermann reaction (compare Expt 6.113). The product, prepared by the above method, is, however, highly satisfactory. Commercial zinc cyanide may also be used. 

The yields in the Gattermann reaction, however (e.g. o-bromotoluene, Expt 6.74), are usually not as high as those obtained by the Sandmeyer method. Copper powder is also employed in the preparation of sulphinic acids (e.g. benzenesul-phinic acid, Expt 6.75) which are obtained when a solution of a diazonium sulphate is saturated with sulphur dioxide and decomposed by the addition of copper powder. 

Gattermann and Wieland, "Laboratory Methods of Organic Chemistry, 22nd ed., pp. 286-289, Macmillan Co., New York, 1932. 

Gattermann, Ludwig (1860—1920). A German organic chemist, noted for laboratory methods Ref Hackh s Diet (1944), 571-L... 

Amino groups at the 3-, 4-, 5-, or 6-positions in pyridazine 1-oxides have been successfully replaced by chlorine or bromine in the Gattermann reaction, but yields of 3-chloro (or bromo) derivatives are low. As there are no other suitable methods, this reaction provides the most convenient synthesis of 5- and 6-halo-pyridazine 1-oxides. In this manner 3-, 4-, 5-, and 6-bromopyridazine... 

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