Tris j

Sodium or tetramethylammonium triacetoxyborohydride has become the reagent of choice for diastereoselective reduction of P-hydroxyketones to antidiols. Trialkylborohydrides, eg, alkaH metal tri-j -butylborohydrides, show outstanding stereoselectivity in ketone reductions (39). 

A noteworthy development is the use of KH for complexing alkylboranes and alkoxyboranes to form various boron hydrides used as reducing agents in the pharmaceutical industry. Potassium tri-j -butylborohydride [54575-50-7] KB(CH(CH2)C2H )2H, and potassium trisiamylborohydride [67966-25-0] KB(CH(CH2)CH(CH2)2)3H, are usefiil for the stereoselective reduction of ketones (66) and for the conjugate reduction and alkylation of a,P-unsaturated ketones (67). 

Tlie freezing points of alkanolaiuines are moderately high as shown in Tables 1 and 2. Tlie ethaiiolamiiies, monoisopropaiiolamiiie and inono-j d -butaiiolainiiie, are colorless Hquids at or near room temperature. Di- and tiiisopropaiiolainiiie and di- and tri-J -butanolamine are wliite soHds at room temperature. 

The composition of the products of reactions involving intermediates formed by metaHation depends on whether the measured composition results from kinetic control or from thermodynamic control. Thus the addition of diborane to 2-butene initially yields tri-j iAbutylboraneTri-j -butylborane. If heated and allowed to react further, this product isomerizes about 93% to the tributylborane, the product initially obtained from 1-butene (15). Similar effects are observed during hydroformylation reactions however, interpretation is more compHcated because the relative rates of isomerization and of carbonylation of the reaction intermediate depend on temperature and on hydrogen and carbon monoxide pressures (16). 

Finally, there is a series of publications by Prinzbach and co-workers on 4,7-dihydro-l//-l,4,7-triazonine 42b (80CB3127, 80CB3161, 88CB757, 89AG1386). Tliis compound, obtained by a 3valence isomer) is a nonaromatic, nonplanar 127r-electron system, better represented as 42c. 

Hsu, S. and Soban, E. (1982) Color modification of diaminobenzidine (DAB) precipitation by metallic ions and its application for double immunohistochemis-try. J. Histochem. Cylochem. 30, 1079. 

Addition of excess methanol destroys the silver complexes and regenerates the phosphamethin-cyanine salts. It is more advantageous to bind the Ag ions by addition of tris-j cyanoethyl-phosphine. 

BOR borate or borax KHP potassium biphthalate THAM, TRIS J tr i s(hydroxymethyl)-... 

While CdS and CeSe quantum dots are particularly luminescent and have been used extensively, there are concerns over their application in medical imaging in particular because of the potential toxicity associated with cadmium. As a result the syntenthesis of alternative luminescent nanoparticles based on less toxic materials such as Zn3P2 stabilised by tri-/j-octylphosphine oxide is an active area of endeavour.41... 

E. Dubler, M. Textor, H. R. Oswald, and A. Salzer, X-Ray Structure Analysis of the Triple-Decker Sandwich Complex Tris(j -cyclopentadienyl)dinickel Tetrafluoroborate,... 

This class of complexes has been studied extensively [236]. The spectroscopy of lanthanide /J-diketonatcs was intensively studied during 1960 s and 1970 s because of their potential application in liquid lasers. Two species, viz., tetrakis /J-dikctonates [LnfdikctL]- and tris /J-diketonatcs [Ln(diket)3], have been characterized. The latter neutral complex accepts Lewis bases and forms compounds. The neutral [Ln(diket)3] complexes are both thermally and kinetically stable [237]. 

The significant nephelauxetic effect in the spectra of Nd(III) hydroxyaquobisbenzoy-lacetonate was attributed to resonance in the /J-diketone by Dutt [238], while the others interpreted this to the lower coordination number of six. Anhydrous lanthanide salts mixed with /1-dikctonatcs of the type (LnL1, L11, L111) show markedly greater nephelauxetic effect and intensity than the lanthanide tris /J-diketonates in semiaqueous media which has been attributed to a lower coordination number in anhydrous /J-diketonates [239,240]. 

After 30 min take a dry 10 mL pear-shaped flask filled with argon and stoppered with a septum. To this, add a 0.5 M solution of bis(tri-/j-butylammonium) pyrophosphate in DMF (0.6 mL, 0.3 mmol) and dry tri-/7-butylamine (145 pL, 0.6 mmol). Vortex/mix this mixture for about 30 s and then add to the reaction immediately in one portion. 

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