Acidifying agents sulfuric acid

An aqueous flow system of the type described by Dixon and Norman (7,8) was used. Two aqueous solutions acidified with sulfuric acid were used—i.e., one is a TiCl3 solution and the other a solution of an oxidizing agent (e.g., H202, hydroxylamine, or tert-butyl hydroperoxide), both solutions containing suitable amounts of monomer. The two solutions were mixed rapidly in the flow system immediately before they entered the flat cell in me ESR cavity (for details, cf. Ref. 36). 

The use of acid solutions (mainly hydrochloric, nitric, and sulfuric acids) offers quite high removal yields because metal ions tend to be more soluble at low pH values. A drawback is that the soil becomes acidified—this can introduce major alterations in its chemical, physical, and biological properties in addition, carbonate-rich soils strongly interact with the acids and produce CO2. As discussed in Chapter 3, metal complexes with natural or synthetic chelating agents tend to be soluble and stable. Then, heavy metals in soils can also be solubilized by chelation and extraction followed by an ex situ treatment. 

Sulfuric acid is used as an acidifying agent in a variety of pharmaceutical and food preparations. It may also be used to prepare dilute sulfuric acid, which, in addition to its use as an excipient, has some therapeutic use for the treatment of gastric hypoacidity, as an astringent in diarrhea, or to stimulate appetite. Sulfuric acid has been used in parenteral, oral, topical, and ophthalmic pharmaceutical formulations. 

In most procedures the acid is neutralized when hydrolysis has reached a desired stage. An electrolytic process for the removal of acid has been reported.124 It was found that isostatic processing of starch was faster with starch acidified with hydrochloric acid.125-127 Pre-hydrolysis of starch for further hydrolysis with milder hydrolyzing agents, such as sulfur dioxide, might also be of some benefit.128129... 

Hydroperoxides in ethers can be detected by shaking a small amount of the ether with an acidified 10% aqueous solution of potassium iodide, KI, or by using starch iodine paper with a drop of acetic acid. Peroxides oxidize iodide ion to iodine, I2, which gives a yellow color to the solution. Hydroperoxides can be removed by treating them with a reducing agent. One effective procedure is to shake the hydroperoxide-contaminated ether with a solution of iron(ll) sulfate in dilute aqueous sulfuric acid. You should never use ethers past their expiration date, and you should properly dispose of them before then. 

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 ... 

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