Reactions with Hydrogen tellurides

In the reduction of imines and enamines with hydrogen telluride and sodium hydrogen telluride, hydrolysis leading to primary amines and carbonyl compounds is frequently competitive with the reduction. This undesired side reaction is minimized by the addition of triethylamine, in the case of hydrogen telluride. ... 

In all these reactions alkanols were formed in yields of a few percent. The ditellurium compounds are postulated to be the products of the reaction of hydrogen telluride with the telluroaldehydes that are formed as intermediates from the aldehydes and hydrogen telluride1. 

Sodium hydrogen telluride, (NaTeH), prepared in situ from the reaction of tellurium powder with an aqueous ethanol solution of sodium borohydride, is an effective reducing reagent for many functionalities, such as azide, sulfoxide, disulfide, activated C=C bonds, nitroxide, and so forth. Water is a convenient solvent for these transformations.28 A variety of functional groups including aldehydes, ketones, olefins, nitroxides, and azides are also reduced by sodium hypophosphite buffer solution.29... 

The title reagent (prepared by the reaction of sodium hydrogen telluride with chlorotriph-enylstannane) reacts easily with the more active halides such as benzyl bromides whereas common halides need to be activated by cesium fluoride. 

Organyl tellurols are very unstable compounds owing to their extreme sensitivity to oxygen, giving the corresponding ditellurides. The first short-chain alkyltellurols (C1-C4) have been isolated as yellow liquids with an obnoxious odour, from the reaction of aluminium telluride and hydrogen telluride, respectively, with alcohols and aUcyl bromides. Aryltellurols seem not to have been isolated. As shown in Sections 3.1.3.2 and 3.2.2, aryl tellurolates are... 

Good yields of secondary amines are achieved using both the methods in the reactions of aromatic and aliphatic aldehydes as well as of diaUcyl ketones and cycloalkanones with aliphatic and alicyclic amines (and ammonia). Anilines give low yields, but when 2 equiv is used in the sodium hydrogen telluride method, the yields are improved. In the reaction of ammonia with aldehydes, symmetrical secondary amines are obtained, whereas glu-taraldehyde and amines lead to N-substituted piperidines. 

Sodium hydrogen telluride reacts with epoxides, in accordance with an S 2 displacement, giving rise to telluro-alcohols. These products are useful intermediates since they are easily converted into the corresponding alcohols and ketones by treatment with nickel boride followed by oxidation (reaction (a)) or to alkenes via the corresponding tosylates (reaction b)). ... 

Otherwise, the same products can be obtained by a Knovenagel-type reaction between )3-cyanosulphones and aromatic aldehydes in the presence of sodium telluride (behaving as a base). This result is consistent with the above-formulated desulphonylation of an intermediate a-alkylidene )3-cyanosulphone at the expense of the sodium hydrogen telluride formed during the reaction. 

Hydrogen telluride is prepared by the reaction of aluminum telluride, Al2Te3 with hydrochloric acid ... 

Cadmium arsenide, nitride, selenide. and telluride are known, the first and third ohlainahle front the elements, while the nitride is obtained by heating the amide lubtained by reaction of cadmium thiocyanate and potassium amide in liquid NHi). and (lie telluride is obtainable by reduction ol the lcllurate with hydrogen. Cadmium arsenide is used as a seiniconducinr. 

Isotellurochromenes 151 can be prepared by a ring-closure reaction of 2-ethynylbenzyl bromides with sodium hydrogen telluride (Equation 60) <1998J(P1)2123>. This reaction provided key synthetic intermediates for the preparation of 2-benzotelluropyrylium salts (see Equation (35), Section 7.11.6.2.1). 

Under appropriate experimental conditions, hydrogen telluride, phenyl tellurol, and sodium hydrogen telluride perform the selective reduction of double bonds of a,/3-unsaturated carbonyl systems.89 90 This reaction with a,j3-unsaturated ketones complements the cerium trichloride/sodium borohydride method, which reduces the carbonyl group, keeping the carbon-carbon double bond intact92 (Scheme 18). 

The reaction of nitroalkanes and dinitroalkanes with sodium hydrogen telluride gives nitrosoalkane dimers and olefins, respectively.96 The reduction of other nitrogenated species such as hydroxylamines, azides, nitroso, azo, and azoxy compounds can also be performed by using tellurium reagents.6,11,12... 

The reaction of tellurium with osmium-carbyne complexes1 or with osmium-methylene complexes2, or of sodium hydrogen telluride with iodomethyl(iodo)-osmium complexes3 produced tellurolato-osmium compounds. 

The reverse regiocontrol, giving 1,2-diols, is observed with DIBAL-H (diisobutylaluminum hydride). The remarkable effect of titanium tetraisopropoxide as an additive to lithium borohydride has also been reported. In this reaction benzene is a better solvent than THF, probably because a Ti complex using both oxygens in epoxy alcohols is formed in benzene before the hydride attack. Other metal hydrides used include sodium hydrogen telluride (NaHTe) and an ate complex derived from DIBAL-H and butyllithium, both of which reduce epoxides to alcohols, although they have been tested with only a small number of examples. In the former case the reaction may proceed via a 2-hydroxyalkyltellurol intermediate. 

The CdTe nanocrystals were synthesized by using aqueous solution of cadmium perchlorate and electrochemically produced hydrogen telluride with mercaptopropionic acid (MPA) as a stabilizer. The pH of the synthesis solution was maintained at 12, the precursors molar ratio was Cd Te MPA 2 1 2.6. The size of NCs depends on the refluxing time of the reaction mixture and may be tuned from ca. 2 up to ca. 6 nm. 

Silastannathianes containing the unit SiSSn can be prepared from the reaction of a mixture of tin halide and silicon halide with hydrogen sulfide in the presence of an amine, and the corresponding selenium and tellurium compounds from a similar reaction using lithium selenide or lithium telluride.14... 

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