Acidifying agents diluted

Reducing agents, e.g. zinc, tin(II) chloride solution, colour a molybdate solution acidified with dilute hydrochloric acid blue (probably due to Mo3+), then green and finally brown. 

Glacial and diluted acetic acid solutions are widely used as acidifying agents in a variety of pharmaceutical formulations and food preparations. Acetic acid is used in pharmaceutical products as a buffer system when combined with an acetate salt such as sodium acetate. Acetic acid is also claimed to have some antibacterial and antifungal properties. 

Hydrochloric acid is widely used as an acidifying agent, in a variety of pharmaceutical and food preparations (see Section 16). It may also be used to prepare dilute hydrochloric acid, which in addition to its use as an excipient has some therapeutic use, intravenously in the management of metabolic alkalosis, and orally for the treatment of achlorhydria. See Section 17. 

In pharmaceutical formulations, dilute hydrochloric acid is usually used as an acidifying agent in preference to hydrochloric acid. Hydrochloric acid is also used therapeutically as an escharotic. The PhEur 2005 also contains a specification for hydrochloric acid, dilute see Section 17. 

Chromic acid, in the form of its anhydride generally, dissolved in glacial acetic add, or as a water solution of potassium dichromate or sodium didiromate acidified with dilute sulphuric add, can also be used as an oxidising agent, not only in the case in hand, but also for the oxidation of alcohols, ketones, etc. In oxidation reactions, two molecules of chromic anhydride (Cr03) give three atoms of oxygen ... 

Other natural soil acidifying agents are found in the atmosphere. Carbon dioxide has a concentration of only 350 parts per million (by volume) in the open atmosphere, so that rainwater in equilibrium with this air is a very dilute solution of carbonic acid (10 M). This source of H2CO3 is of much less consequence than the carbonic acid generated from biological activity within soils. Lightning can oxidize atmospheric nitrogen, N2, to produce NO which further oxidizes to nitric acid ... 

Alcohols can be oxidised by potassium dichromate(Vl) solution, K Cr O, acidified with dilute sulfuric acid. The solution s orange colour is caused by the dichromate(Vl) ions, CrjOy faq). When the dichromate(Vl) ions react as an oxidising agent, they themselves are reduced and turn into chromium(lll) ions, Cr faq), which form a green solution. The reaction mixture needs to be warmed before the oxidation takes place. 

Once again, the oxidising agent used is a solution of potassium dichromate(VI), acidified with dilute sulfuric acid. To produce a ketone, this oxidising agent must be heated with a secondary alcohol. The ketone formed cannot be further oxidised, even if we reflux the reaction mixture and add excess oxidising agent. Therefore we do not need to distil out the ketone product immediately. 

Write a balanced equation for the oxidation of butan-2-ol to butanone, using [0] to represent an oxygen atom from the oxidising agent. What do you observe in the reaction vessel if the oxidising agent used in part b i is potassium dichromate(VI) solution, acidified with dilute sulfuric acid, and the reaction mixture is heated ... 

To a mixture of 10 g. of the compound and 3-5 ml. of 33 per cent, sodium hydroxide solution in a test-tube, add 2-5 ml. of 50 per cent, chloroacetic acid solution. If necessary, add a little water to dissolve the sodium salt of the phenol. Stopper the test-tube loosely and heat on agently-boiling water bath for an hour. After cooling, dilute with 10 ml. of water, acidify to Congo red with dilute hydrochloric acid, and extract with 30 ml. of ether. Wash the ethereal extract with 10 ml, of water, and extract the aryloxyacetic acid b shaking with 25 ml. of 5 per cent, sodium carbonate solution. Acidify the sodium carbonate extract (to Congo red) with dilute hydrochloric acid, collect the aryloxyacetic acid which separates, and recrystallise it from hot water. 

A mixture of 34.4 g (100 mmol) 5-benzoyl-N-methyl-N-phenyl-2,3-dihydro-lH-pyrrolizine-l-carboxamide, 25 g sodium hydroxide in 25 mL water, and 80 mL methanol was refluxed for 5 hours. The mixture was cooled to room temperature, stirred under nitrogen for sixteen hours, and then diluted with 80 mL of water. The mixture was extracted with toluene, and the aqueous and organic phases were separated. The aqueous phase was acidified with 6 N hydrochloric acid. The resulting precipitate was extracted with dichloromethane. The combined extract was treated with activated clay decolorizing agent (4.5 g) for 30 minutes, filtered, and concentrated by... 

A stereoselective GC method for determination of etodolac enantiomers in human plasma and urine was first reported as a preliminary method [35], and then as a validated method [36]. Sample preparation involved addition of (S)-(+)-naproxen (internal standard) and sodium hydroxide to diluted plasma or urine. The samples were washed with diethyl ether, acidified with hydrochloric acid, and extracted with toluene. ( )-(+)-naproxen was used as a derivatizing agent to form diastereomeric derivatives of etodolac. The gas chromatograph system used in this work was equipped with fused-silica capillary column (12 m x 0.2 mm i.d.) coated with high-performance cross-linked methylsilicone film (thickness 0.33 pm) and a nitrogen-phosphorous detector. The operating conditions were injector 250°C detector 300°C column 100-260°C (32 °C/min). 

Reactions and Detection.—Permonophosphorie acid is a strong oxidising agent. It liberates iodine at once from acidified potassium iodide (cf. Caro s acid) and oxidises manganous salts in the cold to permanganates. Hydrolysis in dilute solutions is represented by the equation... 

Test for reducing agents Acidify 5 drops of the soda extract with dilute sulphuric acid and add 3 drops of dilute sulphuric acid in excess. Add 2-3 drops of dilute potassium permanganate solution (prepared by dilution of 1 drop of... 

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