|
β-Butyrolactone
β-Butyrolactone is the Intramolecular reaction, intramolecular carboxylic acid ester (lactone) of the optically active 3-Hydroxybutanoic acid, 3-hydroxybutanoic acid. It is produced during chemical synthesis as a racemate. β-Butyrolactone is suitable as a monomer for the production of the biodegradable polyhydroxyalkanoate Polyhydroxybutyrate, poly(3-hydroxybutyrate) (PHB). Polymerisation of racemic (''RS'')-β-butyrolactone provides (''RS'')-polyhydroxybutyric acid, which, however, is inferior in essential properties (e.g. strength or degradation behaviour) to the (''R'')-poly-3-hydroxybutyrate originating from natural sources. Production β-Butyrolactone is obtained in 63% yield by the addition of ethanal to ethenone (ketene) in the presence of the Clay minerals, clay mineral montmorillonite. For this purpose, ethenone can also be produced in-situ by dehydrobromination of acetyl bromide with the Hünig base diisopropylethylamine. In the presence of a chiral aluminium comp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pascal (unit)
The pascal (symbol: Pa) is the unit of pressure in the International System of Units (SI). It is also used to quantify internal pressure, stress, Young's modulus, and ultimate tensile strength. The unit, named after Blaise Pascal, is an SI coherent derived unit defined as one newton per square metre (N/m2). It is also equivalent to 10 barye (10 Ba) in the CGS system. Common multiple units of the pascal are the hectopascal (1 hPa = 100 Pa), which is equal to one millibar, and the kilopascal (1 kPa = 1000 Pa), which is equal to one centibar. The unit of measurement called '' standard atmosphere (atm)'' is defined as . Meteorological observations typically report atmospheric pressure in hectopascals per the recommendation of the World Meteorological Organization, thus a standard atmosphere (atm) or typical sea-level air pressure is about 1013 hPa. Reports in the United States typically use inches of mercury or millibars (hectopascals). In Cana ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
