Sodium hydroxide.mono-hydrate

Both mono- and disodium phosphates are prepared commercially by neutralization of phosphoric acid using sodium carbonate or hydroxide. Crystals of a specific hydrate can then be obtained by evaporation of the resultant solution within the temperature range over which the hydrate is stable. For the preparation of trisodium phosphate, sodium hydroxide must be used to reach the high end pH because CO2 cannot be stripped readily from the solution above a pH of near 8. 

The solubility of sodium hydroxide at —20° is 16 0, and at 192°, 83 9. The solubility curve of potassium hydroxide 29 shows the existence of the mono-, di-, and tetra-hydrates. There is a eutectic near —66° with a 30 per cent. KOH soln. between ice, and tetrahydrated potassium hydroxide, K0H.4H20, which passes into dihydrated potassium hydroxide at about —32-7°. The dihydrate is deposited when cone. aq. soln. are cooled. The small acute rhombohedral crystals melt at... 

Hydration of terminal alkynes to methyl ketones is a valuable synthetic transformation. The reverse conversion, viz. from a methyl ketone to an alkyne can also be a useful transformation. One of the most effective (but largely neglected) procedures for the conversion ArCOMe— ArC =CH has been shown to be the reaction of the acetophenone with two equivalents of POCI3 in DMF followed by treatment of the intermediate thus produced with a hot solution of sodium hydroxide in aqueous dioxane. The method can be used to prepare mono-, di- and triethynylarenes in 30-50% yield. 

Hydroboration with borane and various mono- or dialkyl boranes followed by oxidation with hydrogen peroxide/sodium hydroxide leads to an anti-Markovnikov cis hydration of a C —C multiple bond1 2. 

Decomposition of model substances method The third method of calibration is by carrying out an experimental run using certain well studied model substances such as copper sulfate pentahydrate, calcium carbonate, calcium oxalate mono hydrate, potassium carbonate, sodium hydroxide, zinc oxalate dihydrate, and benzoic acid. These model substances show well resolved dehydration and decomposition temperatures over a wide temperature range. 

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