Magnesium hydroxide, alkalizer

A variety of adverse effects have been reported following the use of antacids. If sodium bicarbonate is absorbed, it can cause systemic alkalization and sodium overload. Calcium carbonate may induce hypercalcemia and a rebound increase in gastric secretion secondary to the elevation in circulating calcium levels. Magnesium hydroxide may produce osmotic diarrhea, and the excessive absorption of Mg++ in patients with renal failure may result in central nervous system toxicity. Aluminum hydroxide is associated with constipation serum phosphate levels also may become depressed because of phosphate binding within the gut. The use of antacids in general may interfere with the absorption of a number of antibiotics and other medications. 

Ethyl-2-methyl-3-(10,11) -dihydro-5H-dibenzo [a,d] cycloheptene-5-ylidene)-1 -pyrrolinium iodide (4.7 g) was dissolved in 7 cc of methanol. To this solution there were added 1.4 g of sodium boron hydride within about 80 minutes with stirring and stirring of the solution was continued for two hours to complete the reaction. The reaction mixture was acidified with 10% aqueous hydrochloric acid solution and then the methanol was distilled off. The residual solution was alkalized with 20% aqueous sodium hydroxide solution and extracted with ether. The ether layer was dried over magnesium sulfate and the ether was distilled off. The resulting residue was further distilled under reduced pressure to yield 2.0 g of 1-ethyl-2-methyl-3-(10,11 ) dihydro-5H-dibenzo[a,d]cycloheptene-5-ylidene)pyrrolidine (boiling point 167°C/4 mm Hg.). 

From 4.1 parts DL-4-(aminomethyl)-l-[2-(l,4-benzodioxanyl)methyl]-4-phenylpiperidine dihydrochloride, the free base is liberated in the usual manner and extracted with chloroform. The organic layer is separated, dried and evaporated. The DL-4-(aminomethyl)-l-[2-(l,4-benzodioxanyl)methyl]-4-phenylpiperidine obtained is dissolved in 128 parts anhydrous chloroform. This solution is cooled to 5°C and there is added dropwise a solution of 1.6 parts acetylchloride in 7 parts anhydrous chloroform (exothermic reaction). The reaction mixture is stirred over night at room temperature and then alkalized with about 25 parts sodium hydroxide 20% at a temperature of 20°C. The aqueous layer is separated and extracted twice with chloroform. The combined organic layers are washed with water, dried over magnesium sulfate, filtered and evaporated. The oily residue is dissolved in a mixture of 40 parts acetone and 20 parts diisopropyl ether and evaporated again. The solid residue is triturated in diisopropylether, yielding DL-4-(N-acetylaminomethyl)-l-[2-(l,4-benzodioxanyl)-methyl]-4-phenylpiperidine melting point 140°-141.1°C, as a white microcrystalline powder. 

A solution of 2 parts of DL-2-(acetylimino)-3-[2-hydroxy-2-(2-thienyl)ethyl]thiazoline in 16 parts of thionylchloride and 45 parts chloroform is stirred and refluxed for one hour. After cooling the whole is extracted with water. The acid aqueous solution is separated, washed with toluene, alkalized with ammonium hydroxide solution and extracted with chloroform. The extract is dried over magnesium sulfate and evaporated. The oily residue is dissolved in 40 parts boiling 2-propanol. To this warm solution is added a warm solution of an equivalent quantity of oxalic acid dihydrate in 2-propanoL After cooling to room temperature, the precipitated oxalate is filtered off and dried in vacuum, yielding DL-5,6-dihydro-6-(2-thienyl)imidazo[2,l-b]thiazole oxalate MP 192°-193°C. 

An aqueous solution of this salt is alkalized with ammonium hydroxide and extracted with toluene. The extract is dried over magnesium sulfate and evaporated. The oily residue is crystallized from 12 parts xylene. The solid is filtered off and dried in vacuum, yielding DLI-5,6-dihydro-6-(2-thienyl)imidazo[2,l-b]thiazole MP 58°-62°C. 

The residual solution was alkalized with 20% aqueous sodium hydroxide solution and extracted with ether. The ether layer was dried over magnesium sulfate and the ether was distilled off. The resulting residue was further distilled under reduced pressure to yield 2.0 g of l-ethyl-2-methyl-3-(10,ll)-dihydro-5H-dibenzo[a,d]cycloheptene-5-ylidene)pyrrolidine (boiling point 167°C/4 mm Hg.). 

Currently, most cocoa powders are produced by the so-called Dutch or alkalized process, in which the nib is treated with a warm aqueous solution of up to three parts of anhydrous potassium carbonate to 100 parts of nib (or equivalent amounts of other alkalis such as potassium bicarbonate and hydroxide carbonates, bicarbonates, and hydroxides of sodium, magnesium, and ammonium or their combinations). After the alkali is completely absorbed, the nib is processed as in the above method to yield alkalized cocoa powder. Alkalized cocoa is considered to have improved dispersibility, color, and flavor over unalkalized cocoa. 

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