From other carbonyl halides

SYNTHESIS OF PHOSGENE FROM OTHER CARBONYL HALIDES... 

After separation of excess amalgam a solution of MXj is added. Reaction is rapid and the desired product can be separated from the Na halide or NaCN produced. If the separation of the amalgam is incomplete it is possible for Hg to be incorporated into the product (see 8.3.3.4). To avoid this, other methods of preparing carbonyl anions can be used, such as reaction with NaBH4, Na-K and other reducing agents ", or phase-transfer methods. ... 

Organopalladium intermediates are also involved in the synthesis of ketones and other carbonyl compounds. These reactions involve acylpalladium intermediates, which can be made from acyl halides or by reaction of an organopalladium species with carbon monoxide. A second organic group, usually arising from any organometallic reagent, can then form a ketone. Alternatively, the acylpalladium intermediate may react with nucleophilic solvents such as alcohols to form esters. 

The synthesis of pentacarbonyl rhenium(I) halides, Re(CO)5X, succeeded from simple and complex rhenium halides below 200 atm of CO at 200° C. The compounds are extraordinarily stable and form easily, often quantitatively, from carbon monoxide and rhenium metal in the presence of other heavy metal halides or halogen sources such as CC14. Later we prepared the corresponding carbonyl halides of manganese (67) and technetium (68) from their respective carbonyls. It was found that the corresponding binuclear tetracarbonyl halides [M(CO)4X]2 (M = Mn, Re) could be made by heating the mononuclear M(CO)5X complexes (15, 69), as well as by other methods. 

The use of a Lewis acid to promote the abstraction of a halide anion from a metal halide complex, in the presence of a neutral ligand, has been widely employed to produce both substituted and totally unsubstituted metal carbonyl cations. The halide acceptor most generally used is aluminum trichloride, but other Lewis acids have been employed, as indicated below. The requirements for the halide acceptor include that the anion product should be sufficiently large to stabilize the salt formed (15). 

The four-coordinate sqnare planar iron(n) porphyrins discussed above are not only of great valne in heme protein model chemistry, but also in chemical applications, since they undergo a wealth of ligand addition reactions. For example it has been shown that TPPFe complexes are active catalysts for important carbon transfer reactions in organic chemistry and are found to catalyze the stereoselective cyclopropanation of aUcenes, olefin formation from diazoalkanes, and the efficient and selective olefination of aldehydes and other carbonyl compounds. The active species in these carbon transfer reactions are presumably iron porphyrin carbene complexes. " It was also found that ferrous hemin anchored to Ti02 thin films reduce organic halides, which can pose serious health problems and are of considerable environmental concern because of their prevalence in groundwater. ... 

Osmium pentacarbonyl is a convenient precursor to other osmium carbonyl complexes. Hydrogenation gives the dihydride OsH2(CO)4. This hydride is not acidic with a p/fa of 18.5 but it can be deprotonated by strong bases to give [OsH(CO)4] and reduced by sodium (Scheme 23). Substitution of CO on Os(CO)5 by trialkyl or triarylphosphines, arsines, or stibenes gives Os(CO)4L or Os(CO)3L2. Other carbonyl phosphine complexes result from the reduction of osmium halides by alcohols in the presence of the tertiary phosphine. 

Acid anhydrides as activated derivatives of carboxylic acids have found little attention for the preparation of acid halides. Their use can be justified if they are obtained from other sources than from carboxylic acids, e.g. phthalic anhydride from the oxidation of naphthalene or o-xylene. It is, therefore, no surprise that there exist patents to convert phthalic anhydride to phthalic acid dichloride with carbonyl dichloride in the presence of catalysts. " However, there are some methods available thus a,a-di-chloromethyl methyl ether will convert acid anhydrides to acid chlorides and brenzcatechyl phosphorus tribromide will also achieve this transformation. Fluorides may be prepared similarly with the pyridine/HF mixture of 01ah. °... 

The carbonyls are in general volatile compounds with an extensive chemistry which presents many problems as regards valence and stereochemistry. Some are reactive and form a variety of derivatives, as shown in Chart 22.1 for the iron compounds, while others are relatively inert, as for example, Cr(CO)6 etc. and Re2(CO)iQ. This rhenium compound, although converted to the carbonyl halides by gaseous halogens, is stable to alkalis and to concentrated mineral acids. A few carbonyls may be prepared by the direct action of CO on the metal, either at atmospheric pressure (Ni(C0)4) or under pressure at elevated temperatures (Fe(CO)s, Co4(CO)i2)- Others are prepared from halides or, in the case of Os and Re, from the highest oxide. The polynuclear carbonyls are prepared photo-synthetically, by heating the simple carbonyls, or by other indirect methods. 

The oxo-dechlorination of CCI3F (CFC-11) using SO 3 constitutes the most convenient laboratory preparation of COCIF, and analogous reactions may be employed for the preparations of the other mixed and symmetrical carbonyl halides, such as COBrF - from CBr3F and SO 3, and COBr - from CBr, and SO 3 [1874,1875], SO 3 and CCI3F combine in the presence of HgSO and Hg SO or sulfuric acid as follows ... 

There are very few experimentally-recorded spectroscopic data for COBrF, and only one publication [1596] exists in which the spectroscopic properties of COBrF have been studied for their own sake. Apart from the recording of a F n.m.r. spectrum and a mass spectrum [1163], the remaining spectroscopic studies of COBrF have been confined to the recording of its infrared spectrum [1596], and to the derivation of spectroscopic correlations with other members of the carbonyl halide series [604,864,1860],... 

As with a number of the other unsymmetrical halides, carbonyl fluoride iodide was flrst reported in the FIAT review of German science (1939-1945) [1196a,1751]. The compound was prepared by Kwasnik [1196a, 1751] from the reaction of iodine]V) fluoride with carbon monoxide according to ... 

Radical carbonylations of 4-alkenyl halides are distinguished from those of other alkenyl halides, since an acyl radical resulting from a 4-alkenyl radical and CO is ready to undergo rapid 5-exo cyclization to form 3-oxocyclopentylcarbinyl radical. 

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