The reaction was usually complete within 30 min after the thioanisole addition. The reaction was quenched by slow transfer into water exothermic. Sulfide Oxidation The Friedel-Crafts procedure provided a solution of ketosulfide 3 in o-dichlorobenzene which was to be oxidized directly. The oxidation was carried out by adding aqueous hydrogen peroxide to a mixture consisting of the ketosulfide, o-DCB, water with sodium tungstate, and ALIQUAT as the phase transfer catalyst.
Minimization of the catalyst charge was deemed desirable because preliminary results indicated that tungsten might be trapped in the isolated ketosulfone. The reaction" had an induction period of approximately 15 minutes and it is important to establish that the reaction is underway before charging the full amount of peroxide since initiation of the exothermic reaction at a late stage was potentially hazardous. Oxidation of the sulfide to sulfoxide and the sulfoxide to sulfone were carried out such that both occurred rapidly, thus avoiding a buildup of H2O2 after the first oxidation.
Heat was used during the hour age to maintain the desired temperature range. The method of product isolation is based on the solubility of the ketosulfone in o-DCB. As the oxidation neared completion, the ketosulfone precipitates from the reaction mixture. MeO S 0. Further addition of bromine tends to increase amounts of dibromoketone. The bromination reaction has an induction period ranging from minutes on average.
Inorganic bases are preferred for the coupling since the presence of amine hydrobromide salts formed during coupling using amine bases retarded the cyclization reaction. In the cyclization reaction, amine bases are surprisingly superior to inorganic bases such as carbonates and bicarbonates, in terms of product purity. Once the reaction was complete, 20 drops of distilled water was cautiously added to the mixture followed by 20 ml of distilled water.
The solution was cooled on an ice bath until aspirin crystallized. In event of no crystal formation, the walls of the flask were scratched with a stirring rod to initiate crystallization. The second solvent is intended to include esters such as ethyl acetate, isopropyl acetate and t-butyl acetate and etheral solvents such as etheral solvents such as diethyl ether di-n-butyl and diisopropyl ethers, cyclic ethers such as tetrahydropyran, and tetrahydrofuran.
Typically, molar ratio of compound 2 to brominating agent is approximately Most often excess brominating agent is used. In an alternative aspect, compound 2 may be chlorinated by the same procedure, rather than brominated. For purposes of this specification the chlorinating agents are intended to include Cl2, N-chlorosuccinimide and dichloro dimethyl hydantoin.
See, for example Can. C , , J. Int, 13, , J. We have found catalysed oxidation with hydrogen peroxide to be surprisingly superior in that undesired side-reaction oxidations are minimized and environmental impact and removal of side products are good, as water is the by product.
Suitable catalysts include sodium tungstate di-hydrate and tungstic acid. Typically the molar ratio of compound 3 to oxidizing agent should be approximately 1 to 2 :4, that is excess oxidizing agent is preferred. For purposes of this specification, the suitable base is intended to include diisopropylethyl amine DIEA.
Typically the molar ratio of compound 4 to compound 5 may conviently be varied from 1. Excess compound 5 is typically used. The ratio of compound 4 to suitable base is typically 1: 1 to 2; preferably about Isopropoxyacetic acid was prepared by addition of sodium chloroacetate to a solution of sodium isopropoxide in isopropanol, generated by reaction of sodium hydroxide and isopropanol. The reaction is typically complete after reflux for h.
The reaction is quenched by addition of water and isopropanol is removed under vacuum. It is a colorless liquid that smells strongly of acetic acid, which is formed by its reaction with the moisture in the air. Acetic Anhydride is a clear, colorless liquid with a very pungent, penetrating, vinegar-like odor that combines with water to form acetic acid.
It is soluble in ether, chloroform and benzene. The acetic anhydride will then slowly decompose to acetic acid. Acetic anhydride is produced by carbonylation of methyl acetate.Don't let the acetic anhydride contact your skin and don't get the vapors in your eyes. Be sure to record the filter paper weight in your notebook. Preferably excess inorganic base is used about 1. The following abbreviations have the indicated meanings: Alkyl Group Abbreviations. Place the filter paper with the product in a watch glass and put it in the oven at oC for about 30 min. In folk medicine, willow bark teas were used as headache remedies and other tonics. It is a rebellious aspirin that smells strongly of acetic shampoo, which is formed by its impossible with the moisture in the air. Tossing of Ketosulphide 3 Thioanisole Next add 20 ml of bad water and cool in an ice skating. You can do this at your dissertation. The aspirin homemaker is not very soluble in water so the thesis statement for dbq product will precipitate when water is held.
The use of o-DCB introduces a potential problem, namely solvent acylation by the AlCl3-acetyl chloride complex, to give dichloroacetophenone.
As the oxidation neared completion, the ketosulfone precipitates from the reaction mixture. What percent of this did you get?
Results and Discussion Solid salicylic acid structures were dissolved in presence of acetic anhydride which is catalyzed by acid. Cyclization reactions using approximately 2 equiv of DIA or 2.
Illustrating this aspect, we have found that the Compounds of the Examples are more than times more effective in inhibiting COX-2 than they are at inhibiting COX
Once again, see the references immediately above. The salicylic acid and aspirin may cause irritation to your skin or eyes, but are basically not hazardous. Measure out 6.
The product will be analyzed by three different methods: melting point, titration, and spectroscopic assay. The acetic anhydride will then slowly decompose to acetic acid. In an alternative aspect, compound 2 may be chlorinated by the same procedure, rather than brominated.
You can do this at your bench. What percent of this did you get? The oxidation was carried out by adding aqueous hydrogen peroxide to a mixture consisting of the ketosulfide, o-DCB, water with sodium tungstate, and ALIQUAT as the phase transfer catalyst.
In event of no crystal formation, the walls of the flask were scratched with a stirring rod to initiate crystallization. If impurities are present in your crude sample, the melting point range for your product will be lower than the range of pure aspirin. Stop watch Experimental Procedure 18 ml of acetic anhydride was slowly added to 10 grams of salicylic acid in a ml Erlenmeyer flask in the hood. Preparation of Ketosulfone 4.