Iodine organometallic compounds

Combustion of transition metal organometallic compounds produces a mixtures of simple compounds (metal oxides, carbon oxides, water, nitrogen) which is subject to exact analysis. Thermal decomposition or high temperature iodination of the same compounds cannot necessarily be expected to produce simple materials, with the result that identification is often a difficult problem. This is typified by diene derivatives of iron carbonyl10, where side reactions of the dienes (e.g. polymerization) follow disruption of the iron-diene bonds. The oligomeric mixture can be parti-... 

A sample of organolithium compound solution is added to an excess of standardized iodine solution in Et20 the excess iodine is extracted with aqueous KI and titrated with standard thiosulfate solution. Evaluation of the organometallic compound is made according to equation. A possible interference can be expected from the couphng reaction in equation 20. This was shown to be neghgible, as demonstrated spectrofluorometrically for phenyllithium , whereas a low titer was found for n-BuLi, attributable to this side... 

Organometallic compounds can react with biomine to give bromides, but because organometallic compounds are frequendy made from bromides the reaction with iodine to give iodides is of more synthetic significance (24). 

Ketones can be a-brominated on solid phase by treatment with synthetic equivalents of bromine, such as pyridinium tribromide (Entry 2, Table 6.1) or phenyltri-methylammonium tribromide (DCM, 20 °C, 3 h [10]). Resin-bound organometallic compounds, such as vinylstannanes [11] or organozinc derivatives [12], react cleanly with iodine to yield the corresponding vinyl or alkyl iodides (see also Section 3.13). Additions of halogens or their synthetic equivalents to C=C double bonds on cross-... 

As already discussed (Section 5.2.3), a-metallated ketones were converted by IOB into a-methoxyketones, in presence of methanol. Generally, various organometallic compounds react readily with hypervalent iodine reagents undergoing an umpolung of reactivity the intermediates formed need not be isolated, since they may react in situ with a variety of nucleophiles. A simple example illustrating the point is the... 

Organometallic compounds of magnesium, mercury, or lithium have been treated with iodine or bromine to form organic halides. The method has been successful for obtaining neopentyl iodide where other methods have failed (92%). It has been found convenient in the synthesis of 9-iodoanthracene (53%) and certain heterocyclic halides. ... 

Thallium diphenyl bromide was first mentioned by Meyer and Bertheim in 1994, but in 1922 the present authors showed that this compound was impure, and that the reactions given for it did not represent the facts, as shown by them later preparation. They therefore claimed their preparation to be the first organometallic compound of thallium, in the aromatic series, to be obtained in the pure state. The compound, which is typical of the aromatic thallium diaryl halides, does not melt below 300 C., and may be crystallised from pyridine. The corresjjond-ing chloride is decomposed "by iodine monochloride according to the equation ... 

Anionic reactions cannot be used for this allylation. If the iodine were metallated, the organometallic compound would immediately expel the carboxylate anion as a good leavin group. The radical is stable because the C-O bond is strong and not easily cleaved in radic. reactions. 

Whereas iodinations of polar organometallic compounds in most cases are carried out with elemental iodine (see for example Exp. 40) the aggressive nature of chlorine may give rise to side and subsequent reactions, or reactions with the organic solvent. However, there are a number of compounds, containing so-called positive... 

Attempts to halogenate sp3-alkalimetal compounds in many cases lead to the formation of dimeric products as a consequence of a very fast subsequent reaction of the organometallic compound with the halogen derivative initially formed. Effective suppression of this reaction is only possible in conversions of less strongly basic organometallic compounds (e.g., enolates) with iodine the alkali-metal compound has to be added to the strongly cooled solution of iodine in Et20 or THF. 

Diaryliodonium compounds can be prepared by acid-catalyzed condensation of iodoso aryls with another aryl molecule (equation 129). Another method is the use of iodine trichloride in reaction with organometallic compounds (equations 130 and 131). RICI2 may be prepared by direct chlorination of RI (R = CF3CH2, CHF2(01 2)5CH2) and these materials can be used to chlorinate iodobenzene to give the less hydrolytically stable compound PhlCR. ... 

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