Potassium tris borate

Synthetically useful stereoselective reductions have been possible with cyclic carbonyl compounds of rigid conformation. Reduction of substituted cyclohexanone and cyclopentan-one rings by hydrides of moderate activity, e.g. NaBH (J.-L. Luche, 1978), leads to alcohols via hydride addition to the less hindered side of the carbonyl group. Hydrides with bulky substituents 3IQ especially useful for such regio- and stereoselective reductions, e.g. lithium hydrotri-t-butoxyaluminate (C.H. Kuo, 1968) and lithium or potassium tri-sec-butylhydro-borates or hydrotri-sec-isoamylborates (=L-, K-, LS- and KS-Selectrides ) (H.C. Brown, 1972 B C.A. Brown, 1973 S. Krishnamurthy, 1976). 

Interaction of the thiophene-containing organomercury compounds 272 (R = H, Me, Et) [74MI1, 79JCS(D)2037] with potassium tris(3-methylpyrazolyl) borate (KTp ) yields 273 [96JOM(515)213],... 

Reaction of [RuC12(C6H6)]2 (la), in acetonitrile, with pyrazole, 3,5-dimethylpyrazole, or potassium tris(3,5-dimethylpyrazolyl)borate, K[HB-(Me2pz)3], proceeds by substitution of all chlorides and affords complex 16 (Scheme 1), resulting from the coupling of acetonitrile with pyrazole (22). The reaction of la with tetrakis(l-pyrazolyl)borate ion in boiling acetonitrile, however, led to the trisubstituted derivative 17, the structure of which was established by an X-ray diffraction study (26). 

Boron is determined by oxidation of tri(sec-butyl)borane to 2-butanol.911,12 A 4.0-mL aliquot of the potassium tri(sec-butyl)hydro-borate(l — ) solution is hydrolyzed by adding it, with stirring, to a mixture of... 

Selection of the appropriate counterion is also important. Lithium ion has the lowest mobility of the alkali earth metals. Its use provides for a low-conductivity buffer. Sodium salts are used more frequently due to purity and availability. It makes little sense to ever use a potassium salt. Dual-buffering systems with low-mobility ions and counterions (Tris-phosphate, Tris-borate, aminomethylpropanediol-cacodylic acid) are effective in minimizing buffer conductivity. These buffers are often used in the slab-gel, where low conductivity is particularly important. 

BF3-(CH3)sN Boron fluoride-tri-methylamine, 5 26 BF4H Tetrafluoroboric acid, 1 25 BF4K Potassium tetrafluoro-borate, 1 24... 

Sand-sodium base. See Sodium-sand base a-Santalene, 42 Sobering process, 118-119 Schiff bases. See Imines 9,10-Secosteroids (calciferols and tachysterols), 31-32, 34, 281-283, 289 Seebach-Frater alkylation, 27. AT-Selectride = potassium hydrotris(l-mcthylpropyl)borate(l —) (KBHBVl), 107 XS-Selectride 1 — potassium tris(l,2-dimethyl-propyl)hydroborate(l —) (KBHSiay), 107 Z-Selectride = lithium hydrotri (l-... 

Poloxamer 124 Poloxamer 407 Polyamide Polycarbonate Polyethylene glycol Polyisobutene Polyvinyl butyral Potassium, alum anhydrous Potassium tri polyphosphate PPG-20 Sodium allyloxy hydroxypropyl sulfonate Sodium borate Sodium borate decahydrate Sodium laureth sulfate Sodium nonoxynol-6 phosphate... 

Darses and co-workers have published a series of papers on the synthesis of stereo-defined trisubstituted alkenes by the coupling of readily available unreactive MBH adducts with either organoboronic acids or potassium tri-fluoro(organo)borates in the presence of a rhodium complex via a reaction pathway involving a 1,4-addition/p-hydroxy elimination mechanism. Compared with the aforementioned Pd-catalyzed cross-coupling reaction, this reaction does not need the activation of the hydroxyl group with acetate or carbonate therefore it is more desirable, particularly in terms of atom economy. For the MBH adducts derived from methyl acrylates, the initial reported catalyst, [ Rh-(cod)Cl 2], was active at 50 °C for boronic acids and at 70 °C... 

Reaction of potassium tris(pyrazolyl)borate with [Pd(Me)2(pyridazine)] or [Pd(Me)(Ph)(tmeda)] produces the anions [Pd(Me)(R)(HB pyrazolyl 3)], R = Me, Ph respectively. Treatment with wet ketone produces the Pd(IV) alkyls [Pd(Me)2(R)(HB pyrazolyl)3)]. The trimethyl product has been ciystallographically charactmsed. The net reaction is oxidation of Pd(II) by water accompanied by a methyl group transfer. Allenyl and propargyl halides add trans across the metal centres in [Pd(PPh3)4] and [Pt(PPh3)4], The isomerisation of the o- allenyl products [M(X)(CH=C=CRR )] has been studied and the crystal structure of one example has been determined. 

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

Stereoselective reduction of 3-ketogibberellin adds.1 The 3-ketogibberellin acid 1 is reduced by this borohydride almost entirely to the 3/(-alcohol. Reduction with lithium tri-.wr-hutylhorohydride proceeds with the opposite stereoselectivity. The dilfcrence is considered lo be the result of differences in size between potassium and lithium borate complexes with the carboxylic acid group. 

---