Search results
Results From The WOW.Com Content Network
Thioanisole is an organic compound with the formula CH 3 SC 6 H 5. It is a colorless liquid that is soluble in organic solvents. It is the simplest alkyl–aryl thioether. The name indicates that this compound is the sulfur analogue—the thioether rather than the oxygen-centered ether—of anisole. It can be prepared by methylation of thiophenol.
Boronic acids are known to bind to active site serines and are part of inhibitors for porcine pancreatic lipase, [2] subtilisin [3] and the protease Kex2. [4] Furthermore, boronic acid derivatives constitute a class of inhibitors for human acyl-protein thioesterase 1 and 2, which are cancer drug targets within the Ras cycle. [5]
Phenylboronic acid or benzeneboronic acid, abbreviated as PhB(OH) 2 where Ph is the phenyl group C 6 H 5 - and B(OH) 2 is a boronic acid containing a phenyl substituent and two hydroxyl groups attached to boron. Phenylboronic acid is a white powder and is commonly used in organic synthesis.
Borinic acid, also known as boronous acid, is an oxyacid of boron with formula H 2 BOH. Borinate is the associated anion of borinic acid with formula H 2 BO −; however, being a Lewis acid, the form in basic solution is H 2 B(OH) − 2. Borinic acid can be formed as the first step in the hydrolysis of diborane: [1] BH 3 + H 2 O → H 2 BOH + H 2
Removal of the BOC group in amino acids can be accomplished with strong acids such as trifluoroacetic acid in dichloromethane, or with HCl in methanol. [2] [3] [4] A complication may be the tendency of the t-butyl cation intermediate to alkylate other nucleophiles; scavengers such as anisole or thioanisole may be used.
The C–B bond of boronic acids and esters are slightly longer than typical C–C single bonds with a range of 1.55-1.59 Å. The lengthened C–B bond relative to the C–C bond results in a bond energy that is also slightly less than that of C–C bonds (323 kJ/mol for C–B vs 358 kJ/mol for C–C). [ 6 ]
Fumaric acid is (E)-1,4-but-2-enedioic acid, a trans isomer, whereas maleic acid is the corresponding cis isomer, i.e. (Z)-1,4-but-2-enedioic acid (see cis-trans isomerism). Fumaric acid has pK a values of approximately 3.0 and 4.5. By contrast, maleic acid has pK a values of approximately 1.5 and 6.5.
The reaction of boron trichloride with alcohols was reported in 1931, and was used to prepare dimethoxyboron chloride, B(OCH 3) 2 Cl. [3] Egon Wiberg and Wilhelm Ruschmann used it to prepare tetrahydroxydiboron by first introducing the boron–boron bond by reduction with sodium and then hydrolysing the resulting tetramethoxydiboron, B 2 (OCH 3) 4, to produce what they termed sub-boric acid. [4]