Dialkyl anions oxidative addition

The dimethyl(hydrido)platinum(iv) complex with tris(3,5-dimethylpyrazolyl)borate (Tp ) as a ligand 992 can be obtained as a stable complex by protonolysis of the anionic dimethylplatinum(ii) complex (Equation (185))7 Similar reactions of HCl and Mel with the dimethyl and diphenyl complexes produce trimethyl-, diphenyl(hydrido)-, and diphenyl(methyl)platinum(iv) complexes. Addition of B(G6F5)3 to the platinate in hydrocarbon solvents leads to a dialkyl(hydrido)platinum(iv) complex 993, probably via abstraction of a methyl ligand followed by oxidative addition of the solvent to the Pt(ii) center (Equation (186)). ... 

The selectivity of the aldol addition can be rationalized in terms of a Zimmer -man-Traxler transition-state model with TS-2-50 having the lowest energy and leading to dr-values of >95 5 for 2-51 and 2-52 [18]. The chiral copper complex, responsible for the enantioselective 1,4-addition of the dialkyl zinc derivative in the first anionic transformation, seems to have no influence on the aldol addition. To facilitate the ee-determination of the domino Michael/aldol products and to show that 2-51 and 2-52 are l -epimers, the mixture of the two compounds was oxidized to the corresponding diketones 2-53. 

Phosphorus is a common component of additives and appears most commonly as a zinc dialkyl dithiophosphate or triaryl phosphate ester, but other forms also occur. Two wet chemical methods are available, one of which (ASTM D1091) describes an oxidation procedure that converts phosphorus to aqueous orthophosphate anion. This is then determined by mass as magnesium pyrophosphate or photochemically as molybdivanadophosphoric acid. In an alternative test (ASTM D4047), samples are oxidized to phosphate with zinc oxide, dissolved in acid, precipitated as quinoline phosphomolybdate, treated with excess standard alkali, and back-titrated with standard acid. Both of these methods are used primarily for referee samples. Phosphorus is most commonly determined using x-ray fluorescence (ASTM D4927) or ICP (ASTM D4951). 

Zinc dialkyl/diaryl dithiophosphates are widely used as antiwear additives in engine oils to protect heavily loaded engine parts from excessive wear. They are also used as antiwear agents in hydraulic fluids. The salts are effective oxidation and corrosion inhibitors, they also act as detergents. During friction, these salts form anion-radicals that are successfully cleaved (Kajdas et al. 1986). 

The presence of unsymmetrical dialkyl ditcllurium and unsymmetrical diaryl ditellurium" compounds in solution was confirmed by Te-NMR spectroscopy H-NMR spectroscopy , and mass spectroscopy . Cyclohexyl methyl ditellurium was claimed to have been isolated from a reaction mixture obtained by sequential addition of cyclohexyl bromide and methyl iodide to a solution of tetratelluride anions in dimethylformamide . The chromophoric Te —Te group in the aliphatic and aromatic ditellurium compounds imparts a characteristic orange to red color caused by an absorption maximum at approximately 400 nm. Most of the aromatic ditellurium derivatives are stable as solids toward atmospheric agents, but oxidize slowly when dissolved. The short-chain aliphatic ditellurium compounds are distillable red liquids having an obnoxious odor that clings to skin and clothes. Ditellurium compounds with more than ten carbon atoms in each aliphatic group are low melting solids that can be handled in air. 

The Michaelis-Arbuzov reaction works well for the less complex aroyl and alkanoyl chlorides, where purification by distillation is possible. Moreover, there has been less success in the preparation of oc,P-unsaturated acylphosphonates, where multiple addition products are often observed. Recourse has been found in an attractive route that entails oxidation of dialkyl 1-hydroxyalkyl- or 1-hydroxyaryIphosphonates produced by nucleophilic addition of dialkyl phosphites to carbonyl compounds under basic conditions (Pudovik reaction). Alkali metal salts of dialkyl phosphites are currently used in the Pudovik reaction, and the more common procedure of generating the anion involves the addition of a small amount of alcoholic alkoxide ion to the reaction mixture. Neutral amines represent an alternative to the use of anionic bases. In recent years, the use of solid-phase materials as basic catalysts has been successfully developed (Scheme 7.7). One system involves the addition of basic alumina to the carbonyl compound and dialkyl phosphite the other involves the addition of KF or CsF to the mixture of carbonyl compound and dialkyl phosphite. - Such a process for generating dialkyl 1-hydroxyalkyIphosphonates is very flexible and accommodates a large variety of carbonyl compounds. 

Butyl-2,4,6-trinitrobenzene was obtained in 79% yield, in addition to dialkyl substituted 1,3,5-trinitrobenzene (14%) and recovered 1,3,5-trinitrobenzene (5%) (Table 3). Importance of the experimental part also has to be emphasized. To obtain the o -complex of nitroarene with tetraalkylborate anion, you have to mix a solution of this anion (taken in an excess) with a solution of nitroarene and to wait for 2 h followed by electrochemical oxidation of the o -complex at 1.06 V. 

Several papers report on the nucleophilic reactivity of dithiocarbamate ions towards alkyl halides, 1,2-dibromoalkyl compounds, alkyl and aryl chloroformates, chloroacetic acid, chloroacetates, 3-halo-genophthalides, sulphenyl chlorides, sultones, and trialkylam-monium compounds. Examples of a similar reactivity of dithiocarbazate anions have also appeared. " A series of papers deal with addition or addition-elimination reactions of dithiocarbamate - or dithiocarbazate anions with w-nitrostyrene, 2-thioxo-, 2-oxo-, and 2-imino-5-methoxycarbonylmethylidene-4-thiazolidones, dimethyl acetylenedicar-boxylate, and NN -dialkyl phenylpropiolamidines. S-Monoalkylated N-cyanodithioimidocarbonates (492) underwent oxidative ring-closure to give 3-halogeno-l,2,4-thiadiazole sulphides (493) on treatment with halogenating agents. ... 

P-Ketophosphonates are valuable intermediates in the realm of Homer-Emmons alkenation methodology. Acyclic variants are difficult to obtain from enol phosphates due to competing alkyne and allene formation. One solution utilized the dianion derived from a-bromo ketones and trapping with diethyl phosphorochloridate however, only moderate yields of P-keto phosphonates were reported. The most efficient procedure utilizes the anion derived from dialkyl methylphosphonate, addition to an aldehyde, followed by oxidation (eq 8). ... 

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