Compounds high-boiling-point

Karathane A trade name for 2,4-dinitro-6-( 1 -methylheptyl)phenyl crotonate, CJ8H24N2O6, a compound which has both acaricidal and fungicidal activity. It is a red-brown oil of high boiling point, insoluble in water but soluble in most organic solvents. Karathane is used for the control of powdery mildew, and is nontoxic to mammals. 

Acetylsalicylic acid decomposes when heated and does not possess a true, clearly-defined m.p. Decomposition points ranging from 128° to 135° have been recorded a value of 129-133° is obtained on an electric hot plate (Fig. II, 11, 1). Some decomposition may occur if the compound is recrystaUised from a solvent of high boiling point or if the boiling period during recrystallisation is unduly prolonged. 

The polyhydric alcohols of Solubility Group II are liquids of relatively high boiling point and may be detected inter alia by the reactions already described for Alcohols (see 6). Compounds containing two hydroxyl groups attached to adjacent carbon atoms (1 2-glyeols), a-hydroxy aldehydes and ketones, and 1 2-diketones may be identified by the periodic acid test, given in reaction 9. 

The flavor portion of a flavor compound gives it its name, acceptabiUty, and palatabiUty, and provides character fixation of the flavor, ie, relatively high boiling point soflds, usually in combination, are used at concentrations above thek threshold values at use level so that upon dilution the levels remain above threshold value and the perception of the flavor does not change. 

Methylchlorodisilanes are by-products of the dkect-process residue, commonly called high boiling point residue or simply residue, and are formed in about 4% of the total (CH2)2SiCl2 produced, which in 1994 was about 30,000 tons per year. Disilanes are key constituents of the residue, and novel reactions forming Si—Cl bonds have been described (44,45). Some chemical reactions of dkect-process disilanes are shown in Figure 2. Cleavage chemistry of Si—Si compounds with HCl practiced industrially has also been described (47). 

As a starting point for identifying candidate solvents, all compounds having boiling points below that of any component in the mixture to be separated should be eliminated. This is necessary to yield the correct residue curve map for extractive distillation, but this process implicitly rules out other forms of homogeneous azeotropic distillation. In fact, compounds which boil as much as 50°C or more above the mixture have been recommended (68) in order to minimize the likelihood of azeotrope formation. On the other hand, the solvent should not bod so high that excessive temperatures are required in the solvent recovery column. 

A typical example of a volatile impurity that can be found as one of the main impurities in low-quality ionic liquids with alkylmethylimidazolium cations is the methylimidazole starting material. Because of its high boiling point (198 °C) and its strong interaction with the ionic liquid, this compound is very difficult to remove from an ionic liquid even at elevated temperature and high vacuum. It is therefore important to make sure, by use of appropriate allcylation conditions, that no unreacted methylimidazole is left in the final product. 

Compounds of high boiling point are often undetected, particularly in the... 

Compounds such as the refractory carbides, nitrides, and oxides have extremely high boiling points and generally dissoci-... 

Allylchlorosilanes reacted with naphthalene to give isomeric mixtures of poly-alkylated products. However, it was difficult to distill and purify the products for characterization from the reaction mixture due to the high boiling points of the products and the presence of many isomeric compounds. The alkylation of anthracene with allylchlorosilanes failed due to deactivation by complex formation w ith anthracene and the self-polymerization of anthracene to solid char. 

Hydrogen bonding accounts for the abnormally high boiling points of, e.g., water, hydrogen fluoride, ammonia, and many organic compounds (see later) such as alcohols. 

In steam distillation, steam is introduced into the column to lower the partial pressure of the volatile components. It is used for the distillation of heat sensitive products and for compounds with a high boiling point. It is an alternative to vacuum distillation. The products must be immiscible with water. Some steam will normally be allowed to condense to provide the heat required for the distillation. Live steam can be injected... 

Many substances are not initially appropriate for gas chromatography because of their relatively high boiling points or insolubility. In such cases it is often possible to modify the compound chemically and render it more amenable to separation. In some instances, the chemical modification is used to enable easier detection of the compound, e.g. the introduction of a halogen for use with electron capture detectors. 

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