Higher-boiling halogenated compounds

Determination of nitroaromatics and higher-boiling halogenated compounds in water... 

Nitroaromatics, approx. 0.1 - 6 pg/ml in nanograde acetone (Table A) Higher-boiling halogenated compounds, approx. 0.5-15 pg/ml in nanograde acetone (Table B)... 

Samples Higher boiling halogen compounds DB170 No. Min. Area-% Name... 

Nitro-compounds have often a yellow or red colour, are with difficulty or not at all volatile, possess a much higher boiling-point than the corresponding halogen derivatives, and are denser than water, and insoluble in that liquid. 

The chemical names of these products conform to practice in the United States. Halogens are listed in alphabetical order as bromo, chloro, fluoro, and iodo. For mixtures, the higher pressure material is listed first. An exception to this rule is found in some aerosol propellant mixtures where products not containing fluorine (hydrocarbons, chlorinated compounds, etc.) are listed last. Higher boiling fluorocarbons are usually placed with other fluorocarbons in order of decreasing pressure. 

The reason why boiling points of completely shielded compounds rise if the halogens are replaced by others with a higher atomic number will be dealt with later in Section 51. 

The hydrogen and halogen carbonyls and the nitroso carbonyls Co(NO)(CO)3, in which all bonds are covalent, are non-polar compounds with relatively low boiling points. The dimeric carbonyl, too, is non-polar, but its boiling point is much higher than that of the monomeric carbonyls because of the larger size of the molecule. 

Table 13.2 shows some of the properties of the trihalides of the Group VA elements. Several trends in the data shown in Table 13.2 are of interest. For example, the trihalides of phosphorus and arsenic can be considered as covalent molecules. As a result, the intermolecular forces are dipole-dipole and London forces that are weak. Therefore, the melting and boiling points increase with molecular weight as expected. The trifluorides of antimony and bismuth are essentially ionic compounds and the melting points are much higher than those of the halogen derivatives that are more covalent. 

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