Diphenylsilanediol

Diphenylsilanediol [947-42-2] M 216.3, m 148 (dec). Crystd from CHCl3-methyl ethyl ketone. 

The diethylammonium salt of the tris(tetraphenyldisiloxanediolato)zirconate(IV) anion (33) has been obtained in very low yield from the reaction of [Zr(NEt2)4] with diphenylsilanediol in THF. The ligand results, under the basic reaction conditions, from condensation of two Ph2Si(OH)2 molecules. Anion (33) has an octahedral tris-chelate structure with a twist angle (46.9°) that indicates some distortion towards trigonal prismatic geometry.466... 

However, analogous diorganosilanediols 43b are relatively stable compounds. For example, diphenylsilanediol (44), having no carbon analogue, is an isolable crystalline compound, which is easy to prepare by hydrolysis of diphenyldichlorosilane, diphenyldialkoxysilanes, and other diphenyl-substituted hydrolyzable silanes. 44 was synthesized for the first time by Kipping as early as 191263). 

Remarkable is the fact that diphenylsilanediol and its hydrolyzable prodrugs show a relative wide range between anticonvulsant and neurotoxic dose levels. 

Pharmacokinetic studies (e.g. plasma levels in dogs after peroral or intravenous application, tissue distribution in the rat after intravenous administration) with 44 in several animals have been carried out using l4C-labelled diphenylsilanediol and high pressure liquid chromatography. The elimination half-lives were found to be 1.7 h in mice, 7.2 h in rats, and 6.5 h in dogs after peroral application. 

Preliminary studies of the metabolism of 44 in dogs resulted in the metabolites 58 and 59. Additionally, appreciable amounts of diphenylsilanediol could be isolated from both bile and urine. It is not clear so far whether these compounds are excreted as conjugates or not. 

The poly-(diphenylsiloxane)-diols, HO(Si02O)DH (n = 2,3,4) were obtained by Kipping and Robison (35) by treating diphenylsilanediol with ammonium hydroxide and by Burkhard (13) by hydrolyzing the corresponding a, co-dichlorides in tert-amyl alcohol-toluene solution. Tetra-/>-chlorophenyldisiloxanediol and hexa >-chlorophenyI-1,5-tri-sil-oxanediol were recently isolated by Schott and Berge (61). 

Another striking conversion in the phenyl series of siloxanes is that which produces the cyclic tetramer. Diphenylsilanediol is dissolved in boiling alcohol, and a few drops of aqueous caustic are added. Upon cooling, the distinctive crystals of octaphenyleyclotetrasiloxane separate.37 Apparently strong bases bring about the condensation of diol to tetramer almost exclusively, whereas strong acids favor the formation of almost all trimer. Since both condensation reactions proceed at very moderate temperatures it cannot be said that the molecular form assumed by the product is determined by the temperature. 

Silanediol. A dihydroxy derivative of a silane a compound of silicon containing two hydroxyl groups attached to the same silicon atom, as in diphenylsilanediol, (CeH5)2Si(OH)2... 

Compounds of type 1, where n = 2, are formed in high yield (typically 80-90%) from the reaction between either an organic diol, boric acid and l,l,3,3-tetraphenyldisiloxane-l,3-diol in 2 2 1 molar ratio (Eq. 1) or, the diol, boric acid and diphenylsilanediol in unit molar ratio... 

Polyurethane coatings have been prepared from silicon-containing hydroxy compounds on the basis of symmetrical bis(hydroxymethyl)decamethylpentasiloxane (200). diphenylsilanediol (200). high molecular weight organosilicon polyols (198) or the type... 

Several silanediols can be synthesized by hydrolysis of diorganyldihalogenosilanes with dilute alkali solutions (NaOH or NaHC03). Thus, diethylsilanediol (539) is obtained from diethyldichlorosilane (538), and diphenyldichlorosilane affords diphenylsilanediol (540) (equations 266 and 267)291. An alternative is the hydrolysis of diorganyldialkoxysil-anes (equation 268)292,293. 

Thus (XX) reacts with phenol in pyridine to form diphenoxysilicon phthalocyanine (XXII), with benzyl alcohol to form (XXIII), and with triphenylsilanol to form (XXIV) (168,170, 200). These complexes sublime readily without decomposition (cf. corresponding aluminum derivatives). Bis(diphenylmethylsiloxy)silicon phthalocyanine, which melts before subliming, is one of the very few metal phthalocyanines which actually melt (873). The siloxy complex (XXIV) may also be prepared in benzyl alcohol, thus implying that the Si—O—Si(Pc)—0—Si backbone is more stable than C—O—Si(Pc)—O—C. The dibenzyloxy derivative (XXIII) reacts with diphenylsilanediol to form bis(benzyloxydiphenylsiloxy)silicon phthalocyanine (XXV). 

---