Formation of Carbonyls

Reaction with carbon monoxide causes dechelation of the N-donor end of the phosphorus-nitrogen bidentate ligands (P-N) in [M(CO)4(P-N)] (M = Cr, Mo, or W P-N = PhaPCHaCHaNMCj, PhjPCHaCHaNEta, PhaPCHaCHaNHa, or PhaPCH -CH2CHjNMe2) andin[Mo(CO)4(P-N)][P-N = (17 R = NH, CHj, CHaCH, or 

CHaCHjCHa)] to afford [M(CO)5(P-N)]. The observed kinetics are second order, first order both in complex and in carbon monoxide. This is considered, however, to be the limiting form (fc i / 2[CO]) of the familiar rate law, 

The exchange reaction between nickelocene and deuterium-labelled lithium cyclo-pentadienide, 

In Volume 3 of these Reports we examined a report on the reaction 

The suitability as models for biological protein systems of protoporphyrin IX (ppIX) and tetraphenylporphyrin (tpp) complexes, [Fe(ppIX)(piperidine)2] and [Fe(tpp)(piperidine)2], has been tested by examining their reactions with CO. Elucidation of the mechanism, 

This reaction and similar reactions, mostly up to 1971, some of relevance to earlier sections in this chapter, have recently been reviewed. The equilibrium 

The solid-state reaction between [PdaCliLg] (L = thiophane, dimethyl sulphoxide, diethyl sulphoxide, or diethyl sulphide) and CO proceeds only when the CO is moistened by methanol. I reliminary cleavage of the dimer bridge by methanol followed by insertion of CO is therefore proposed. Pseudo-first-order rate constants indicate the /raw-effect series thiophane DESO DMSO EtaS. i 

The complexes [( 7-C6H5)2M(CO)] (M = Mo or W) are well characterized stable compounds but formation of [(t7-C5H5)aCr(CO)] from chromocene and CO is found to be reversible. Tungstenocene appears to be unique in forming a stable, formally 20-electron complex [( 7-C5H6)2W(CO)2]. Attempts have been made to account for such behaviour. Replacement of Br in [Mn(CO)6-n(CNMe)n(Br)] by CO and CNMe in the presence of halogen acceptors is found to be stereospecific and a simple dissociative mechanism seems unlikely in view of the probability of fluxional behaviour in a five-co-ordinate intermediate. A closely associated ion pair may therefore precede ligand attack and halide displacement. 

The reactions of simple ferrous porphyrins such as [Fe(TPP)(base)2] with small molecules are of current interest and the kinetics of the reactions of these complexes (base = pyridine, piperidine, or methylimidazole) with O2 and CO at — 79 °C in CH2CI2 are the subject of a recent report. The kinetics of the forward reaction, 

The previous suggestion that a CO-bridged dimer is formed by the reaction of [Co2(CO)s] and CO at 150 °C with CO pressures of 150 atm may be in error. More recent studies assign most of the i.r. bands claimed to be due to such a species to [Co2(CO)g]. Reductive carbonylation of [CoCXXPJ [X = Cl, Br, or I, L = P(OEt)2Ph] proceeds according to the equation 

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Active Raney nickel induces desulfurization of many sulfur-containing heterocycles thiazoles are fairly labile toward this ring cleavage agent. The reaction occurs apparently by two competing mechanisms (481) in the first, favored by alkaline conditions, ring fission occurs before desul-, furization, whereas in the second, favored by the use of neutral catalyst, the initial desulfurization is followed by fission of a C-N bond and formation of carbonyl derivatives by hydrolysis (Scheme 95). 

Nitro alcohols form salts upon mild treatment with alkahes. Acidification causes separation of the nitro group as N2O from the parent compound, and results in the formation of carbonyl alcohols, ie, hydroxy aldehydes, from primary nitro alcohols and ketols from secondary nitro alcohols. 

Syntheses from Dry Metals and Salts. Only metaUic nickel and iron react direcdy with CO at moderate pressure and temperatures to form metal carbonyls. A report has claimed the synthesis of Co2(CO)g in 99% yield from cobalt metal and CO at high temperatures and pressures (91,92). The CO has to be absolutely free of oxygen and carbon dioxide or the yield is drastically reduced. Two patents report the formation of carbonyls from molybdenum and tungsten metal (93,94). Ruthenium and osmium do not react with CO even under drastic conditions (95,96). 

Oxidation of polyethylene with the formation of carbonyl groups can lead to a serious increase in power factor. Antioxidants are incorporated into compounds for electrical applications in order to reduce the effect. 

The acid number is mainly defined for rosins and rosin-derived resins and for phenol-modified resins. Standard hydrocarbon resins have zero acid number because the absence of functional groups. However, the acid number allows one to control deterioration by oxidation with formation of carbonyl and carboxyl groups in hydrocarbon resins. Typical acid number values of different resin types are ... 

Significant stimulated emission is only found for the pristine side of the sample. From these results it was concluded that the photoinduccd absorption that suppresses die stimulated emission is directly or indirectly caused by the presence of oxygen-related defects. It was shown earlier that the effect of photooxidation on the emission properties of PPV can be explained by the formation of carbonyl-groups that act as sLrong electron acceptors leading to an efficient dissociation of the plioh excited slate 29). It can be concluded that the dissociated pair near the defcci leads to the strong photoinduccd absorption. The observation that... 

Formation of carbonyl groups which may occur when polyethylene is overheated, such as in an extrusion coating operation. Here a proper balance between extrudate temperature and exposure time to air is required. 

Radiation cross-linking of PVC in the absence of additives has been reported by several authors [20,21,267,268]. PVC by itself is not readily cross-linkable by EB radiation. In the study of radiation chemistry of PVC, it is known that the oxidation takes place in the presence of atmospheric oxygen during irradiation [269] and hydroperoxide groups are produced on oxidation. The formation of carbonyl group along with the elimination of HCl from PVC on irradiation in air has also been reported [270,271]. 

When a 1 1 carbonate/magnesium mixture was heated, this gave rise to a detonation. This accident was explained by the formation of carbonyl potassium. 

Compounds in which a carbonyl or other nucleophilic functional group is close to a carbenoid carbon can react to give ylide intermediate.221 One example is the formation of carbonyl ylides that go on to react by 1,3-dipolar addition. Both intramolecular and intermolecular cycloadditions have been observed. 

Figure 3. Formation of carbonyl group absorption at 1714 cm in polypropylene samples exposed to ozone and UV light (L2).

Ouyang, J. et al. (1980). Formation of carbonyl compounds from beta-carotene during palm oil deodorization. J. Food Sci. 43 1214-1222. 

Figure 1. Formation of carbonyl groups in 0.1 mm PP films as a function of irradiation time in Xenotest 150 (13). (UVA)2-(2 -hydroxy-3, 5 -di-tert-butylphenyl)-5-chloro-benzotriazole (Ni-Comp) Nickelf2,2 -thiobis-(4-tert-octylphenolate)]-n-butyl-amine (Benzoate) 2,4-di-tert-butylphenyl-3,5-di-tert-buty 1-4-hydroxy-benzoate (HALS) Bis-(2,2,6,6-tetramethyl-piperidinyl-4)sebacate.

In this contribution the analysis of the TPD data obtained for Cu-K-FER zeolite is presented, considering the formation of carbonyl complexes on dual cation sites. 

Nitrogen-containing side chains in amino acids can be altered by oxidation forming chloramines or even become deaminated. The result is often the formation of carbonyls (e.g., aldehydes) and hydroxyls. Lee, S et al. (2006) found that Fe-EDTA-mediated oxidation of human... 

Unfortunately, there are no universal methods to detect all types of protein oxidation, because the products formed can be so diverse in nature. However, some forms of protein oxidation can be assayed using chemical modification (Davies et al., 1999 Shacter, 2000). In particular, the formation of carbonyl groups on proteins can be targeted using the reagent 2,4-dinitrophenyl-hydrazine (DNPH). This compound reacts with aldehydes to form 2,4-dinitrophenylhydrazone derivatives, which create chromogenic modifications that can be detected at high sensitivity in microplate assays or Western blot analysis (Buss et al., 1997 Winterbourn et al., 1999). 

Reactions of metal carbonyls with halogens lead to the formation of carbonyl halide complexes by substitution reactions or breaking metal-metal bonds. The reaction... 

A second type of reaction leading to the formation of carbonylate anions is the reaction of metal carbonyls with strong bases. For example,... 

Acids catalyze the decomposition of secondary hydroperoxide with the formation of carbonyl compounds [46,83]. 

Hydrolysis, or better, hydrogenolysis of the normal ozonide leads to the cleavage of the original carbon-carbon double bond with formation of carbonyl groups. The abnormal ozonide usually decomposes before it reaches room temperature and both the double bond and the adjacent carbon-carbon single bond are found to have cleaved. 

The matrix photochemistry of 2v proved to be fairly complicated.108 The primary product of the photolysis of 2v is carbene lv, which was identified by ESR spectroscopy. Under the conditions of matrix isolation the carbene showed the expected reactivity towards molecular oxygen (formation of carbonyl oxide 7v) and carbon monoxide (formation of ketene lOv) (Scheme 22). In contrast to the oxocyclohexadienylidenes (la and derivatives) carbene lv slowly reacted with CO2 to give an a-lactone with the characteristic C=0 stretching vibration at 1896 cm-1. The latter reaction indicates that lv is — as expected — more nucleophilic than la. 

Shah, H., Hartman, S.P., and Weinhouse, S. 1979. Formation of carbonyl chloride in carbon tetrachloride metabolism by rat liver in vitro. Cancer Res. 39 3942- 3947. 

The fate of thiocyanate in soil is largely uncharacterized. Early studies have shown that thiocyanate can undergo both aerobic (Betts et al. 1979) and anaerobic microbial degradation (Betts et al. 1979 Stafford and Callely 1969 Youatt 1954) however, the degradation pathway has not been defined (Brown and Morra 1993). Saturated soils treated with thiocyanate were found to emit carbonyl sulfide (COS) (Minami 1982 Minami and Fukushi 1981). Katayama et al. (1992, 1993) have reported the formation of carbonyl sulfide from the biodegradation of thiocyanate by pure and mixed cultures of Thiobacillus thioparus. 

Katayama Y, Narahara Y, Inoue Y, et al. 1992. A thiocyanate hydrolase of Thiobacillus thioparus. A novel enzyme catalyzing the formation of carbonyl sulfide from thiocyanate. J Biol Chem 267(13) 9170-9175. 

An isocyanate intermediate may also be involved in the selenium-catalyzed process, which starts with the formation of carbonyl selenide from the reaction between selenium and CO, followed by nucleophilic attack by NuH (Scheme 28). When NuH = primary amine, the resulting RNH(CO)SeH intermediate may eliminate H2Se to give the isocyanate, which then reacts with Nu H to give the final product (Scheme 28, path a). Alternatively, oxidation of Nu(CO)SeH by 02 may lead to a bis(carbamoyl)diselenide species, which is attacked by NuH (Scheme 28, path b). 

Treatment of Fischer-type carbene complexes with different oxidants can lead to the formation of carbonyl compounds [150,253]. Treatment with sulfur leads to the formation of complexed thiocarbonyl compounds [141]. Conversion of the carbene carbon atom into a methylene or acetal group can be achieved by treatment with reducing agents. Treatment of vinylcarbene complexes with diborane can also lead to demetallation and formation of diols [278]. The conversion of heteroatom-substituted carbene complexes to non-heteroatom-substituted carbene complexes... 

Ih Formation of carbonyl compounds and alterations of hyaluronic acid in lung Rabbit 26... 

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