Hydrogen tartrates

Tartaric acid is noteworthy for a) the excellent way in which the majority of its salts Crystallise, and h) the frequent occurrence of salts having mixed cations. Examples of the latter are sodium potassium tartrate (or Rochelle salt), C4H40 NaK, used for the preparation of Fehling s solution (p. 525), sodium ammonium tartrate, C4H OaNaNH4, used by Pasteur for his early optical resolution experiments, and potassium antimonyl tartrate (or Tartar Emetic), C4H404K(Sb0). The latter is prepared by boiling a solution of potassium hydrogen tartrate (or cream of tartar ) with antimony trioxide,... 

Required Potassium hydrogen tartrate, 5 g. antimony trioxide, 5 g-... 

Add 5 g. of potassium hydrogen tartrate and 5 g. of antimony trioxide (each being finely powdered) to 30 ml. of water contained in a small flask, and boil the mixture under a reflux water-condenser for 15 minutes. Then filter hot, using a Buchner funnel and flask which have been preheated by the filtration of some boiling distilled water. Pour the clear filtrate into a beaker and allow to cool. Potassium antimonyl tartrate separates as colourless crystals. Filter, drain and dry. Yield, 5 g. The product can be recrystallised from hot water, but this is usually not necessary. 

Potassium hydrogen tartrate, about 0.034M Saturated at 25°C... 

To prepare the standard pH buffer solutions recommended by the National Bureau of Standards (U.S.), the indicated weights of the pure materials in Table 8.15 should be dissolved in water of specific conductivity not greater than 5 micromhos. The tartrate, phthalate, and phosphates can be dried for 2 h at 100°C before use. Potassium tetroxalate and calcium hydroxide need not be dried. Fresh-looking crystals of borax should be used. Before use, excess solid potassium hydrogen tartrate and calcium hydroxide must be removed. Buffer solutions pH 6 or above should be stored in plastic containers and should be protected from carbon doxide with soda-lime traps. The solutions should be replaced within 2 to 3 weeks, or sooner if formation of mold is noticed. A crystal of thymol may be added as a preservative. 

In the days of alchemy and the phlogiston theory, no system of nomenclature that would be considered logical ia the 1990s was possible. Names were not based on composition, but on historical association, eg, Glauber s salt for sodium sulfate decahydrate and Epsom salt for magnesium sulfate physical characteristics, eg, spirit of wiae for ethanol, oil of vitriol for sulfuric acid, butter of antimony for antimony trichloride, Hver of sulfur for potassium sulfide, and cream of tartar for potassium hydrogen tartrate or physiological behavior, eg, caustic soda for sodium hydroxide. Some of these common or trivial names persist, especially ia the nonchemical Hterature. Such names were a necessity at the time they were iatroduced because the concept of molecular stmcture had not been developed, and even elemental composition was incomplete or iadeterminate for many substances. 

Market prices for ch oline products in 1992 were as follows 70% ch oline chloride(FeedGrade), 0.77/kg choline dihydrogen citrate, 7.20/kg and choline hydrogen tartrate, 9.50/kg. 

Oscine, CgHiaOjN, This substance, for which the name scopolin is in use in continental Europe, was first examined by Hesse and later t Luboldt. It forms colourless, hygroscopic prismatic crystals, m.p. 109 from ether or light petroleum, and boils at 241-3°. cZZ-Oscine has bee resolved into the d- and Z-forms by King by crystallisation of tl d-hydrogen tartrates. The characters of the three forms of oscine and ( their picrates and hydrochlorides are tabulated on p. 87. 

ZZ-Glaucine has m.p. 137-9°, and on recrystallisation of the d- and Z-hydrogen tartrates furnishes the corresponding salts of d- and Z-glaucine, from which the free bases are obtainable, the (Z-glaucine thus produced being identical with the natural alkaloid. 

Glaucidine (item 56 list, p. 173), composition unknown m.p. 209-10°, gives the characteristic colour reactions of glaueine. It is a phenolic base and on methylation gives a product of which the hydrogen tartrate closely resembles that of glaueine. ... 

Hoshino and Kobayashi (1933) have also described the resolution of di-eserethole by crystallising the mixed d-hydrogen tartrates from alcohol, when d-eserethole d-hydrogen tartrate [m.p. 173-4°, [a]D ° + 113° (HgO) ] separated first. The base recovered from the mother liquors yielded with 1-tartaric acid, l-ha.se i-hydrogen tartrate (m.p. 173-4°, [ajj, — 113°). The active picrates had m.p. 133-6° and the di-picrate m.p. 132°. 

The potassium salt of tartaric acid, potassium bitartrate or potassium hydrogen tartrate, is weakly acidic, and is known as cream of tartar. Since it is a dry acid, cream of tartar is used in baking powders (along with sodium bicarbonate) to produce carbon dioxide gas when added to water. Other acids used in baking powder are fumaric acid and phosphoric acid. 

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