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S-(+)-Carvone is the principal constituent (60–70%) of the oil from caraway seeds (Carum carvi), [8] which is produced on a scale of about 10 tonnes per year. [3] It also occurs to the extent of about 40–60% in dill seed oil (from Anethum graveolens), and also in mandarin orange peel oil.
In chemistry, racemization is a conversion, by heat or by chemical reaction, of an optically active compound into a racemic (optically inactive) form. This creates a 1:1 molar ratio of enantiomers and is referred to as a racemic mixture (i.e. contain equal amount of (+) and (−) forms).
A single Adderall dose combines the neutral sulfate salts of dextroamphetamine and amphetamine, with the dextro isomer of amphetamine saccharate and D/L-amphetamine aspartate monohydrate. The original Benzedrine was a racemic mixture, and isolated dextroamphetamine was later introduced to the market as Dexedrine.
[1] [2] Fractions are collected based on differences in a specific property of the individual components. A common trait in fractionations is the need to find an optimum between the amount of fractions collected and the desired purity in each fraction. Fractionation makes it possible to isolate more than two components in a mixture in a single run.
There are five major fractions. Each fraction ends with a specific precipitate. These precipitates are the separate fractions. [4] Fractions I, II, and III are precipitated out at earlier stages. The conditions of the earlier stages are 8% ethanol, pH 7.2, −3 °C, and 5.1% protein for Fraction I; 25% ethanol, pH of 6.9, −5 °C, and 3% protein.
Levopropoxyphene is an antitussive.It is an optical isomer of dextropropoxyphene.The racemic mixture is called propoxyphene.Only the dextro-isomer (dextropropoxyphene) has an analgesic effect; the levo-isomer appears to exert only an antitussive effect.
Levmetamfetamine is excreted in urine 40.8 to 49.0% as unchanged levmetamfetamine and 2.1 to 3.3% as levoamphetamine. [2] [4] [3] The mean elimination half-life of levmetamfetamine ranges between 10.2 and 15.0 hours. [2] [4] For comparison, the elimination half-life of dextromethamphetamine was around 10.2 to 10.7 hours in the same studies.
The Schöllkopf method or Schöllkopf Bis-Lactim Amino Acid Synthesis is a method in organic chemistry for the asymmetric synthesis of chiral amino acids. [1] [2] The method was established in 1981 by Ulrich Schöllkopf. [3] [4] [5] In it glycine is a substrate, valine a chiral auxiliary and the reaction taking place an alkylation.