Rosenmund reactions, quinoline

Ring expansion Chloramine. Diazomethane. Ethyl diazoacetate. Sodium nitrate, Rosenmund reaction Quinoline. 

As catalyst for the Rosenmund reaction palladium on a support, e.g. palladium on barium sulfate, is most often used. The palladium has to be made less active in order to avoid further reduction of the aldehyde to the corresponding alcohol. Such a poisoned catalyst is obtained for example by the addition of quinoline and sulfur. Recent reports state that the reactivity of the catalyst is determined by the morphology of the palladium surface." ... 

Rosenmund reaction. The quinoline-sulfur poison of Rosenmund and Zetzsche is prepared by refluxing 1 g. of sulfur with 6 g. of quinoline for 5 hrs. and diluting the resultant dark brown solution with purified xylene to 70 ml. In reducing 8-naphthoyl chloride to /3-naphthaldehyde, Hershberg and Cason passed hydrogen... 

In the Rosenmund reaction (Eq. 5-84), acid chlorides are hydrogenated to aldehydes. The catalyst is a supported palladium catalyst (5 % Pd/BaS04) poisoned by sulfur compounds such as quinoline, tiourea, or thiophene to prevent further reduction of the aldehyde. 

Rosenmund Reaction. A catalyst poison prepared from quinoline and sulfur is useful for controlling the reaction of p-naphthoyl chloride (19) with hydrogen gas and palladium on barium sulfate catalyst. If control of the reaction is not maintained by catalyst poisoning to reduce activity, further reduction beyond the desired /3-naphthaldehyde product (20) is often observed (eq 13). ... 

Due to its commercial importance, the synthesis of copper phthalocyanine (PcCu) is the best investigated of all the phthalocyanines. Copper phthalocyanine is prepared from phthalonitrile and copper(I) chloride without solvent137 and also in a melt of urea.229,277 Additionally, the insertion of copper into metal-free phthalocyanine in butan-l-ol and pentan-l-ol is possible. The copper salts used in this case are copper(I) chloride112 and copper(II) acetate.290 Starting from copper(II) acetate, copper phthalocyanine can also be prepared in ethylene glycol.127 As mentioned above, copper phthalocyanine often occurs as a byproduct of the Rosenmund-von Braun reaction. To increase the yield of the phthalocyanine the solvent dimethylformamide can be substituted by quinoline. Due to the higher boiling point of quinoline, the copper phthalocyanine is the main product of the reaction of copper(I) cyanide and 1,2-dibromoben-zene.130... 

The synthesis of aldehydes by the Sommclet reaction, the Rosenmund reduction and the Stephens reaction all involve the conversion of a group already present in the molecule. The Rosenmund reduction (Scheme 6.7) is the catalytic hydrogenation of a benzoyl chloride in the presence of a catalyst poison, quinoline/sulfur, which prevents over-reduction to the alcohol. In the Stephens reaction (Scheme 6.7), a nitrile group is reduced by tin(II) chloride and hydrochloric acid to an imine salt, which is then hydrolysed. 

As a classical technique for the synthesis of aromatic cyanides treatment of the corresponding halides with CuCN has to be cited (Rosenmund-von Braun reaction). It is carried out at 15C1-250 C, either without any solvent at all, or using pyridine or quinoline, which also operate as complexing agents for the CuCN. Other heavy metal cyanides or hexacyanoferrates have been used in principle, but their... 

Similar deactivation is observed with bismuth and copper salts. A palladium catalyst poisoned with quinoline-sulfur and support on barium sulfate is used in the Rosenmund-Saytzeff reaction (p. 67). 

This reaction was initially reported by Reissert in 1905 and extended by Grosheintz and Fischer in 1941 It is the synthesis of aldehyde involving the formation of 1 -acyl-2-cyano-1,2-dihydroquinoline derivatives from acyl chlorides, quinoline, and potassium cyanide and the subsequent hydrolysis of said dihydroquinoline derivatives under acidic conditions to produce quinaldic acid and aldehydes. The original procedure occurs smoothly for aroyl or cinnamoyl chloride in liquid SO2 but not in benzonitrile, ether, dioxane, acetone, or CHCb. However, the modification from Grosheintz and Fischer using hydrogen cyanide and 2 eq. quinoline in absolute benzene is also adaptable for aliphatic acid chlorides. This is one of the methods that converts acyl chlorides into aldehydes and is found to be superior to the normal Rosenmund Reduction. For example, o-nitrobenzoyl chloride has been converted into o-nitrobenzaldehyde in 60% yield by the current reaction, whereas the Rosenmund Reduction is not suitable for such conversion. Therefore, this reaction is referred to as the Grosheintz-Fischer-Reissert aldehyde synthesis or Reissert aldehyde synthesis. ... 

Acid chlorides can be reduced to aldehydes either by catalytic hydrogenation or by reaction with a metal hydride. In both cases, the reagent and the reaction conditions are selected to avoid the further reduction of the aldehyde. The conversion of an acid chloride to an aldehyde can be carried out by the Rosenmund reduction, which uses hydrogen gas and a modified palladium catalyst. The palladium catalyst is altered to prevent further reduction of the aldehyde. To prepare the catalyst, the palladium is treated with quinoline, an aromatic heterocyclic amine, and is heated with sulfhr. 

The Rosenmund-von Braun reaction involves the treatment of aryl halides with Cu CN or a 2 1-mixture of K CN/Cul in pyridine, quinoline or an appropriate aprotic polar solvent such as A-methylpyrrolidine (NMP), DMF, DMAC, HMPA at temperatures ranging from 150-250°C". This reaction has been postulated to proceed via organocopper intermediates. The reactivity of aryl-halogen bonds is in the order I > Br > Cl F. The difference in reactivity between Ar-Br and Ar Cl is normally sufficient to permit selective cyanation of the Ar—Br bonds (for example, compounds 2 and 3 ) (Figure 7.2). Discrimination between Ar—Br and Ar—1 bonds, however, is more difficult to accomplish, and therefore mixtures of iodo- and bromo-substituted aryl [ C]nitriles can be expected whenever iodo, bromo aryl dihalides are employed The selechve replacement of iodine... 

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