Effects organic compounds

Studies 1 i 181 of the various organo-nietallic compounds have shown that only those of metals which are capable of ready oxidation are effective. Metals capable of existing in a number of states of oxidation are particularly effective. Organic compounds with the metal atom linked through an oxygen atom are not effective in stopping knock. 

As described previously, the effects of gamma and beta radiation on metal are not permanent. On the other hand, organic material will suffer permanent damage as its chemical bonds are broken by incident gamma and beta radiation. This chapter discusses how radiation effects organic compounds. 

Corrosion in steel systems handling wet oils can be inhibited with both organic and inorganic compounds. Effective organic compounds include various amines, lecithin, and mercaptobenzo-thiazole. The inorganic inhibitors include sodium nitrite and sodium nitrate. Chromates are not used because of their instability in the presence of organic matter. 

The additives for improving the cetane number, called pro-cetane, are particularly unstable oxidants, the decomposition of which generates free radicals and favors auto-ignition. Two families of organic compounds have been tested the peroxides and the nitrates. The latter are practically the only ones being used, because of a better compromise between cost-effectiveness and ease of utilization. The most common are the alkyl nitrates, more specifically the 2-ethyl-hexyl nitrate. Figure 5.12 gives an example of the... 

Hydrogen fluoride also effects replacement reactions in organic compounds. For example, carbon tetrachloride yields a mixture of chlorofluoromethanes CCI3F, CCI2F2 and so on. Like all the other hydrogen halides, hydrogen fluoride adds on to olefins, for example ... 

Solid organic compounds when isolated from organic reactions are seldom pure they are usually contaminated with small amounts of other compounds ( impurities ) which are produced along with the desired product. Tlie purification of impure crystalline compounds is usually effected by crystallisation from a suitable solvent or mixture of solvents. Attention must, however, be drawn to the fact that direct crystallisation of a crude reaction product is not always advisable as certain impurities may retard the rate of crystallisation and, in some cases, may even prevent the formation of crystals entirely furthermore, considerable loss of... 

In the isolation of organic compounds from aqueous solutions, use is frequently made of the fact that the solubility of many organic substances in water is considerably decreased by the presence of dissolved inorganic salts (sodium chloride, calcium chloride, ammonium sulphate, etc.). This is the so-called salting-out effect. A further advantage is that the solubility of partially miscible organic solvents, such as ether, is considerably less in the salt solution, thus reducing the loss of solvent in extractions. 

Divide the saturated solution of n-butyl alcohol in water into three approximately equal parts. Treat these respectively with about 2-5 g. of sodium chloride, potassium carbonate and sodium hydroxide, and shake each until the soli have dissolved. Observe the effect of these compounds upon the solubility of n-butanol in water. These results illustrate the phenomenon of salting out of organic compounds, t.e., the decrease of solubility of organic compounds in water when the solution is saturated with an inorganic compound. The alcohol layer which separates is actually a saturated solution of water in n-butyl alcohol. 

Qualitative analysis for the elements. This includes an examination of the effect of heat upon the substance—a test which inter alia will indicate the presence of inorganic elements—and quahtative analysis for nitrogen, halogens and sulphur and, if necessary, other inorganic elements. It is clear that the presence or absence of any or all of these elements would immediately exclude from consideration certain classes of organic compounds. 

The methods listed thus far can be used for the reliable prediction of NMR chemical shifts for small organic compounds in the gas phase, which are often reasonably close to the liquid-phase results. Heavy elements, such as transition metals and lanthanides, present a much more dilficult problem. Mass defect and spin-coupling terms have been found to be significant for the description of the NMR shielding tensors for these elements. Since NMR is a nuclear effect, core potentials should not be used. 

Modeling the elements discussed in this section is fairly similar to modeling organic compounds. This is primarily because d and/orbitals play a minor role in their chemistry. When d and/ orbitals do affect the chemistry, their effect is well defined and for the most part understood. 

Substitution of fluorine for hydrogen in an organic compound has a profound influence on the compound s chemical and physical properties. Several factors that are characteristic of fluorine and that underHe the observed effects are the large electronegativity of fluorine, its small size, the low degree of polarizabiHty of the carbon—fluorine bond and the weak intermolecular forces. These effects are illustrated by the comparisons of properties of fluorocarbons to chlorocarbons and hydrocarbons in Tables 1 and 2. 

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