#Recristallisation chimie organique series

Rinse the flask with a little ice-water and add the rinsings to the content of the beaker. Make sure to carry out this operation very carefully in the fume cupboard. Allow to cool and slowly pour the oily mixture with stirring into 150 g of crushed ice contained in a 500 mL beaker. When the addition is finished, heat the mixture for 1 h at 100 deg.C to complete the reaction. Equip the funnel with a calcium chloride guard tube and begin the addition of chlorosulfonic acid in small portions while shaking the flask from time to time to ensure thorough mixing. Intermediate A (0.074 mol) in the flask and 25 mL of chlorosulfonic acid (0.385 mol) in the dropping funnel. Latter to a device for the absorption of hydrogen chloride. Equip a dry 250 mL two-necked round-bottomedДЇlask with a dropping funnel and a reflux condenser. When this was complete, the colorless lustrous crystals of intermediate A were filtered and dried under vacuum until the weight was constant. It was then diluted with 100 to 200 mL of water until crystallization of the product occurred. Mixture was briefly stirred and allowed to stand at room temperature for 5 min. Aniline (10 g) and glacial aceticДЄcid (25 mL) were placed in a flask, followed by acetic anhydride (12 g). Occur in human beings, only the bacteria are affected by the drug.

Because the synthesis of folic acid does not Stopping the growth of bacteria (bacteriostatic effect). Para-aminobenzoic acid to a pteridine ring system, thus effectively Sulfanilamide inhibits the formation of folic acid by blocking theДЄctive site of the enzyme which catalyzes the attachment of Human beings, do not synthesize this vitamin, and hence must acquire it in Para-aminobenzoic acid, the central chemical component of folic acid.Д«acteria must synthesize folic acid in order to grow. Sulfanilamide is a competitive inhibitor for the enzymes used to synthesize folic acid, because it resembles Unlike that of most other drugs, the mode of action of the sulfa drugs More than 5000 different sulfa drugs were made and tested, although only a few of them ultimately proved to be of value. This discovery led to an explosion of interest in sulfonamide derivatives. It was concluded that the active portion of Prontosil was the sulfanilamide moiety. Experiments with sulfanilamide showed that it exhibited the same action as Prontosil in vivo and that it was also active in vitro, where Prontosil was inactive. Prontosil breaks down in the body and that only a fragment of the drug molecule works against an infection. TrГ©fouГ«l at the Pasteur Institute in Paris determined that In 1935, a research group headed by Jacques It does not display any medicinalДЄctivity when tested in vitro, that is on a bacterial culture grown in Is when it is injected into a living animal. Prontosil is an effective antibacterial substance in vivo, that The baby lived and soon did Prontosil become widely known and celebrated for its curative powers. The first successful use of Prontosil on humans occurred weeks later, when Domagk gave the drug to a desperate doctor treating an infant dying of bacterial infection. The dye, which was primarily used to color wool, killed the bacteria, and, most importantly, all the mice survived. In 1935, after years of experimentation, Domagk injected an orange-red azo dye called Prontosil into a group of infected mice. He found that some previously successful compounds killed the bacteria in mice but were too toxic to give to humans.

#Recristallisation chimie organique series

Domagk performed a series of experiments on mice infected with streptococcus bacteria. The discovery of sulfa drugs was accomplished by Gerhard Domagk who had been hired in the late 1920s to head the Germany's I.G. However, because bacteria often develop resistance to a particular kind of treatment, sulfa drugs are still used when bacterial tolerance for penicillin has developed. Following the discovery of penicillin, which is as effective although far less toxic, the use of sulfa drugs has somewhat declined. Since sulfanilamide first came into use, more than 150 different derivatives have appeared on the market, chemically modified to achieve more effective antibacterial activity, wider spectrum of microorganisms affected, or more prolonged action.

'Sulfa drugs' is the generic name given to a group of chemotherapeuticДЄgents derived from sulfanilamide, or para-aminobenzenesulfonamide, that are effective against a number of infectious diseases. Interrogation de Seconde Licence 2000-2001