Aromatic acyl halides

Aromatic acyl halides and sulfonyl halides undergo oxidative addition, followed by facile elimination of CO and SO2 to form arylpalladium complexes. Benzenediazonium salts are the most reactive source of arylpalladium complexes. 

Wilkinson s catalyst has also been reported to decarbonylate aromatic acyl halides at 180°C (ArCOX ArX). This reaction has been carried out with acyl iodides, bromides, and chlorides. Aliphatic acyl halides that lack an a hydrogen also give this reaction, but if an a hydrogen is present, elimination takes place instead (17-16). Aromatic acyl cyanides give aryl cyanides (ArCOCN—> ArCN). Aromatic acyl chlorides and cyanides can also be decarbonylated with palladium catalysts. °... 

In a similar reaction, aromatic acyl halides are converted to amines in one laboratory step by treatment with hydroxylamine-O-sulfonic acid. " ... 

Coupling of aromatic acyl halides, with decarbonylation... 

Aromatic acyl halides containing a nitro group adjacent to the halide function show a tendency towards violent thermal decomposition. The few individually indexed compounds are ... 

Cross-linked polystyrene can be acylated with aliphatic and aromatic acyl halides in the presence of A1C13 (Friedel-Crafts acylation, Table 12.1). This reaction has mainly been used for the functionalization of polystyrene-based supports, and only rarely for the modification of support-bound substrates. Electron-rich arenes (Entry 3, Table 12.1) or heteroarenes, such as indoles (Entry 5, Table 15.7), undergo smooth Friedel-Crafts acylation without severe deterioration of the support. Suitable solvents for Friedel-Crafts acylations of cross-linked polystyrene are tetrachloroethene [1], DCE [2], CS2 [3,4], nitrobenzene [5,6], and CC14 [7]. As in the bromination of polystyrene, Friedel-Crafts acylations at high temperatures (e.g. DCE, 83 °C, 15 min [2]) can lead to partial dealkylation of phenyl groups and yield a soluble polymer. 

This is an example of a general reaction that has been observed for aliphatic, alicyclic, and aromatic acyl halides in ketonic solvents (56). 

The conversion of aliphatic and aromatic acyl halides to a keto nitriles has been effected by heating the halides with dry metallic cyanides, of which cuprous cyanide has given the most satisfactory results (60-87%). The acyl bromides rather than the chlorides ate preferred, at least in the formation of aliphatic compounds. Thus, pyruvonitrile is prepared in 77% yield from acetyl bromide and cuprous cyanide whereas no product is obtained if acetyl chloride is employed. Benzoyl cyanide is made in 65% yield by heating the corresponding acyl chloride with cuprous cyanide. "... 

It is also interesting that in the Schotten-Baumann reaction (in which alcohols or amines are acylated in aqueous alkali) there is apparently a selectivity of the aromatic acyl halide for alcohol and amine molecules over water or hydroxide ions. The reason for this selectivity is not clear, but it is an example of the fact that the ease with which a reagent attacks a molecule does not always parallel its basicity (see also p. 112). 

The Michaelis-Arbuzov reaction has been applied to t/7.v(trialkylsilyl) phosphites, which, on reaction with aliphatic or aromatic acyl halides in Et2O or CgHg at room temperature, undergo the rearrangement in mild conditions to produce the valuable fczXtrialkylsilyl) 1-oxoalkyl- or 1-oxoarylphosphonates in good yields (50-77%, Scheme 7.6). - Free acylphosphonic acids are obtained by treatment of the trimethylsilyl) esters with EtOH or by exposure to air for several hours. 

These polymers were then interfacially reacted with di- and trifunctional aromatic acyl halides to give polyamides. Because the only reactive amine groups in these polymers were of the secondary amine type, such polymers should be chlorine-resistant. Dynamic chlorine tests (5 ppm, pH 6.0 to 6.5, 0.5% NaCI, 600 psi, 25°C) of 40 to 80 hours duration appeared to uphold this inference. 

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