Diorgano

Soluble and weU-characterized polygermane homopolymers, (R Ge), and their copolymers with polysdanes have been prepared by the alkaH metal coupling of diorgano-substituted dihalogermanes (137—139), via electrochemical methods (140), and by transition-metal catalyzed routes (105), as with the synthesis of polysdanes. 

Diorgano Sulfates. Dialkyl sulfates up to octadecyl can be made from the alcohols by a general method involving the following reactions (90) ... 

Diorgano Sulfites. Symmetrical or mixed dialkyl sulfites ate prepared by the stepwise reaction of thionyl chloride either with two molecules of an alcohol or with stoichiometric quantities of two alcohols in pyridine (105). 

Reaction of 2,4-diorgano-l,3-diols, such as 2-ethylhexane-l,3-diol, with TYZOR TPT in a 2 1 molar ratio gives the solvent soluble titanate complex, TYZOR OGT [5575-43-9] (4) (73). If the reaction is conducted in an inert solvent, such as hexane, and the resultant slurry is treated with an excess of water, an oligomeric hydrolysis product, also solvent-soluble, is obtained (74). 

Turning now to other types of ceramic fibre, the most important material made by pyrolysis of organic polymer precursors is silicon carbide fibre. This is commonly made from a poly(diorgano)silane precursor, as described in detail by Riedel (1996) and more concisely by Chawla (1998). Silicon nitride fibres are also made by this sort of approach. Much of this work originates in Japan, where Yajima (1976) was a notable pioneer. 

Wiihrenddie Umsetzung von Diorgano-quecksilber-Verbindungen in Aceton unter Ummetallierung ablauft, wird in Alkoholen als Solvens das Quecksilber unter Alkan-Bildung durch Wasserstoff ersetzt (s. Bd. XlII/2b, S. 312). 

Chinol-Derivate werden durch Diorgano-magnesium-Verbindungen im wesentlichen zu Phenolen reduziert (s. Bd. VII/3b, S. 741), Nebenprodukte sind die entsprechenden Oxo-cyclohexadiene. 

Hydrazobenzol reduziert bei hohercn Temperaturen Diorgano-quecksilber-Verbindungen zu Kohlenwas-serstoffen und metallischem Ouecksilber (s.Bd. XIII/2b, S. 312). 

Brommcthyl-naphthyl-(2)- 535 (l-Brom-propyI)-(4-methoxy-phenyl)- 535 (1 -Brom -propyI)-(4-methyI-phenyl)- 535 (1 -Brom-propyI)-phenyI-. 535 tert.-Butyl-phenyl-. 506 Dibenzyl- 465, 488, 506, 524, 534 Dibutyl- 465, 488, 500, 506, 524f., 534, 547 Dimethyl-525, 547.572, 674 Diorgano- 463ff., 488f, 498, 500, 521, 524f. 547, 567... 

Kellum [115] has described a class-selective oxidation chemistry procedure for the quantitative determination of secondary antioxidants in extracts of PE and PP with great precision (better than 1 %). Diorgano sulfides and tertiary phosphites can be quantitatively oxidised with /-chloropcroxybenzoic acid to the corresponding sulfones and phosphates with no interference from other stabilisers or additives. Hindered phenols, benzophenones, triazoles, fatty acid amides, and stearate... 

We found that dichloro diorgano silanes are suitable reagents for the synthesis of diorgano bis(0-alkyl)phosphonates. A different reactivity of both chlorine atoms of the silanes is observed in the dealkylation reaction of dialkylphosphonates in contrast to Me3SiBr [2]. 

The enhanced reactivity of the chlorine atom in the dichloro diorgano silanes can also be observed in Me2(MeO)SiCl 4 or Me(EtO)2SiCl 5. In both cases the O-alkyl O-silylphosphonates (6, 7) are formed in high yields after reaction of 4 or 5 with dialkyl phosphonates. 

Diorgano-l-plumbacycloalkanes or -alkadienes, like 1,1-diethylplumbole, are prepared by the following reactions383,384 ... 

A number of fully organosubstituted iminoboranes has been obtained originating from diphenylketimine or its derivatives and triorganoboranes or di-organohaloboranes. In particular, monomeric (diarylmethyleneamino)diorgano-boranes have been prepared in this manner. Four reaction routes have been used which correspond, in part, to procedures which have also been useful for the synthesis of compounds cited in Sects. Ill and IV 47). 

Table 2 Arrhenius and Eyring activation parameters for the second, Slow reaction observed by stopped-flow spectroscopy in the oxidative addition of halogens to diorgano tellurides 17, 20, and 23-25...

Diorgano diselenides have been used extensively as precursors to seleninic acids in the presence of hydrogen peroxide.The catalytic activity of preformed seleninic acids and seleninic acids generated in situ are identical. Diorgano ditellurides have also been used as catalysts in thiolperoxidase-like reactions for the oxidation of thiols with various peroxides. However, tellurinic acids are not thought to be involved even though RTe(=0)SPh types of structures are proposed as intermediates. 

Dihydrofolate reductases (DHFR), 48, 54, 56 Dimethyl chalcogenides, 131-133 Dimethylselenide, 131-133 Dimethyltellurides, 131-133 Diorgano diselenides, 113 Diorgano ditellurides, 113 Diorganochalcogen(IV) dihalides crystallographic structure, 80f redox reactions, 90 Diorganoselenides... 

Anti-tellurosulphonation of 1-alkynes.A solution of alkyne (1.1 mmol), sodium arylsul-phinate (5 mmol) and diorgano ditelluride (0.5 mmol) in 5 mL of 80% aqueous acetic acid was heated at 80°C for 24 h (R=Ph, 5.2 h). The reaction mixture was diluted with 20 mL of AcOEt, washed with saturated aqueous sodium bicarbonate, dried over Na2S04 and concentrated in vacuum. Crude products, were concentrated under vacuum, and the residues were purified by preparative TLC on silica gel (AcOEt/hexanes, 1 10), treated with 1 equiv of Br2 in AcOEt and concentrated under vacuum. The residues were purified by recrystallization with CH3OH/HCCI3. 

Vinylic tellurides from vinylboranes. To a solution of cyclohexene (10 mmol) in THF (10 mL) was added a solution of diborane (5 mmol) in THF at 0°C with stirring the precipitate thns formed [(c-Hex)2BH] was stirred at 0°C for 1 h. The reaction mixture was diluted with a solution of a terminal acetylene (5 mmol) added at - 10°C, and the mixture was kept at 0°C for 2 h. After the precipitate had dissolved, the resulting solution was treated with 3 M NaOH (2 mL), diorgano diteUuride (4 mmol) and 3% Pd(PPhj)4, then was reflnxed for 3 h under Nj. After the reaction was complete normal work-up was performed. YmylteUurides were isolated and purified by TLC with petroleum ether (30-60°C) as developer. 

Sodium telluride reacts with 1-organo- and l,4-diorgano-l,3-butadyines (prepared in situ by the treatment of the corresponding l,4-dichloro-but-2-yines with NaOH in methanol) to give tellurophenes. ... 

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