Crystallization substances

Then 21.89 g of the hydrochloride salt was dissolved in 600 ml of 80% aqueous ethanol. With the addition of a palladium carbon catalyst, this solution was hydrogenated at room temperature under a hydrogen pressure of about 1.1 atmospheres. After 2 mols hydrogen had been absorbed, the catalyst was filtered off and the filtrate was evaporated in vacuo until crystallization occurred. Then the crystals were dissolved by heating in the smallest possible quantity of water and after cooling, the crystallized substance was filtered off, washed with water and dried in vacuo. The yield was 6.80 g, i.e., 39% of the theoretically possible yield. The resultant product recrystallized from water melted at 203° to 204°C. 

Some crystal substances, such as copper sulfate, have water locked into them. This is known as "water of crystallization, and may affect their color. If blue copper sulfate is heated to drive the water away, a whitish powder is formed - "anhydrous (waterless) copper sulfate. This can be used to test for water. When a liquid such as( pure alcohol is poured onto the powder, there is no color change. But if any water has been added to the alcohol, the copper sulfate powder will turn blue again. This is because it has taken some water from the alcohol-water mixture tp re-form the blue crystals. 

The psychotropic effects of Salvia divinorum have generated interest among psychopharmacologists and other scientists. Chemical analysis of the plant has succeeded in identifying the active substance, which is now known as salvinorin A. Research on animals and human volunteers indicates that the psychoactive effects of salvinorin A are comparable to those of mescaline. As little as 200-500 meg of salvinorin A will reliably produce hallucinations in people, when the crystallized substance is vaporized over a flame and inhaled. On the basis of effective dose, salvinorin A is the most potent natural hallucinogen known. The leaves have been determined to contain 1—4 mg of salvinorin A per gram of dry weight. 

They are crystal substances with high melting temperature (200-400°C). 

Raw stock methylphenyldichlorosilane (not less than 99% of the main fraction) methyl alcohol (not less than 0.5% of humidity) technical carbamide (urea), which is a colourless crystal substance with the melting point of 132-135 °C (not less than 0.2% of humidity) oil or coal toluene (the boiling point is 109.5-111 °C, d/° - 0.865 0.002) activated coal (not less than 0.02% of humidity). 

Raw stock chloromethyltrichlorosilane [fraction with the boiling point of 116-120 °C not less than 85% (vol.), hydrolysed chlorine 56.8-58.8%, d/° = 1.440 -1.470 g/cm3] anhydrous ethyl alcohol (not less than 99.8% of C2H5OH) hexamethylenediamine (colourless crystal substance with the melting point of 39-42 °C, d420 == 0.825 0.828 g/cm3) toluene (d420 = 0.865 0.002 g/cm3, there should be no humidity). 

Pure chloromethylsilatrane is a white crystal substance with a bittter-sweet taste. It is soluble in chloroform and dimethylformamide, less soluble in water and acetone, virtually insoluble in alcohols and diethyl ether. 

Mobus, M., Karl, N. and Kobayashi, T. (1992). Structure of perylenetetracarboxylic dianhydride thin films on alkali halide crystal substances. /. Cryst. Growth, 116, 495-504. [263]... 

Solid bridges can also be formed by crystallizing substances and deposition of colloidal particles at the coordination points in a disperse system. Binding can be caused by different mechanisms. 

In digital clocks, a liquid crystal substance which is... 

Recently, research into the synthesis of a porous crystalline solid with the capability of gas adsorption has attracted increased attention. Since the physical properties of gas adsorption have primarily been developed in the science of the interface of granular materials, it is difficult for chemists who are used to dealing with objects as single-crystal substances. The gas adsorption state can be regarded as a particular kind of crystal state. Recently, an artificial crystalline porous material within an organic frame has been produced, and this material has pliability, unlike a rigid solid substance. This chapter focuses on the new aspects of nanoporosity. 

Adamsit - crystal substance of yellow colour, weakly soluble in water, better soluble in organic solvents average toxic concentration -0,00038 mg/1. 

Dyphcnylchlorarcin - colourless crystal substance with the same characteristics average toxic concentration - 0,00046 mg/1. 

Type of substance White crystal substance Brown powder Slightly yellow crystal substance White powder Yellow crystal substance White Crystal Substance... 

The next method is the crystallization method. This method is very frequently used by crude oil chemists for the classification of lubricating oil fractions. This method is based on difference in the crystallization temperatures of the compounds in the sample. The samples which are analyzed by this method are usually highly viscous. This makes it difficult to separate the crystallized substances from the sample. Consequently, the sample is usually dissolved in a special solvent. Examples of such solvents are liquefied propane, ethyl ether, and a mixture of acetone and toluene. 

As regards the quantitative test of the Heat Theorem in the present case there must be measured, in addition to the heat of fusion, the specific heats of the crystallized substance and of the supercooled liquid down to low temperatures, if possible into the region of the T -law in both cases. The former series will not now in general offer any particular difficulty, but the examination of the liquid form is hindered by the fact that supercooling down to temperatures as low as desired is possible only in the rarest cases. 

Paraffin-like, crystal substance at low temp, mp about 20. USE Waterproof coatings, polishes, face creams, rouges, ointments, soaps, rubber manuf, dye solns, inks, lubricants. 

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