Rosenmund substitution

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... 

Aristolochic acids, representatives of the substituted 10-nitrophenanthrene-l-acids, have been known since 1943, when Rosenmund and Reichstein first isolated aristolochic acid I (1) from A. clematitis (23) [this compound was named aristolochic acid A by Tomita and Sasagawa (24)]. Its structure was elucidated by Pailer et al. in 1956 by means of chemical reactions (25), and when several aristolochic acids—aristolochic acids II (2) (aristolochic acid B by Tomita), III (3) Ilia (4) (aristolochic acid C by Tomita), IV (5), and IVa (6)—were isolated from the root of A. clematitis by Pailer and his co-workers (26) and in the meantime from A. debilis and A. fangchi by Sasagawa (27). 

Side Note 16.2. Figure 16.8 shows a nucleophilic aromatic substitution reaction conducted with copper Rosenmund-von-Braun cyanide. This Rosenmund-von-Braun reaction is not included among the numerous Ull-... 

It is not possible to construct an invariant nucleophilicity order because different substrates and different conditions lead to different orders of nucleophilicity, but an overall approximate order is NH2 > PhaC > PhNH (aryne mechanism) > ArS > RO > R2NH > ArO > OH > ArNHi > NH3 > 1 > Br > Cl > H2O > ROH. As with aliphatic nucleophilic substitution, nucleophilicity is generally dependent on base strength and nucleophilicity increases as the attacking atom moves down a column of the periodic table, but there are some surprising exceptions, for example, OH, a stronger base than ArO , is a poorer nucleophile. In a series of similar nucleophiles, such as substituted anilines, nucleophilicity is correlated with base strength. Oddly, the cyanide ion is not a nucleophile for aromatic systems, except for sulfonic acid salts and in the von Richter (13-30) and Rosenmund-von Braun (13-8) reactions, which are special cases. 

Fluoro- and chloro-substituted styrene epoxides can be converted to the corresponding substituted phenylacetaldehydes over ZSM-5 with selectivities of 90 % and higher [23]. These products are not obtainable via the Rosenmund reduction. 

ROSENMUND BRAUN AromaticCyanation Cu catalyzed nucleophilic substitution o( aromatic halogen by cyanide (see Ullman-GokJberg). 

Another important class of reactions involves the introduction of a cyano group by substitution in an Ar-Z precursor. In fact, novel pathways leading to aromatic nitriles-for example, photosubstitution reactions-are desirable in view of the many applications of aryl cyanides as agrochemicals and pharmaceuticals. Today, the classical copper(l)-mediated Rosenmund-von Braun and Sandmeyer reactions, from aryl halides and aryldiazonium salts respectively, have been supplanted by reactions which employ palladium- or copper-catalysis [57]. The rather common use of excess cyanide anion may lead to a deactivation of the catalyst, and affect to a remarkable extent each of the key steps of the catalytic cycle [58aj. Although the use of complex iron cyanide has been shown to offer an effective solution to this limitation [58b,c], photocyanation provides an equally useful alternative [10],... 

The desired liquid crystals are generally synthesized from substituted ortho-dibromobenzene. In a Rosenmund-von-Braun reaction it is converted into the corresponding dicyano compound. Treatment with ammonia leads to the isoindoline from which the substituted phthalocyanine is obtained (Scheme 13). 

W. A. Goedel, G. Holz, G. Wegner, J. Rosenmund, G. Zotti, Electrochemical investigations of a substituted oxidation stable polypyrrole, Polymer 1993, 34, 4341. 

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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