Hydrocarbons qualitative organic analysis

Figure 5.13 Solubility curve of acids, alcohols, and hydrocarbons. (From Kamm, O. Qualitative Organic Analysis, 2nd ed. Wley New York, 1932. Reprinted with permission of John Mley Sons, New York.)...

One difficulty was that the apparatus, simple to a physicist, appeared very complex to a chemist. The application of mass spectrometry of chemistry had to await the commercial production of instruments. The impetus came in the 1940s when the war effort demanded rapid and accurate hydrocarbon analysis in connection with aviation fuels. The next big step came in the 1950s when it was realized that in addition to quantitative analysis the technique could be used for the qualitative (structural) analysis of organic compounds. A certain resistance had to be overcome to induce mass spectrometrists to put dirty compounds into their instruments rather than clean hydrocarbons. This gave mass spectrometer manufacturers a further impetus to develop more and more advanced instruments and led to a new discipline - organic mass spectrometry. 

Compositional analysis is concerned with determining structural relationships in the molecules present in a sample. Inhared spectroscopy is the most commonly used tool for qualitative chemical analysis of viscous oils. Descriptions and tables of characteristic absorbance for a variety of organic functional groups are readily available in many textbooks. Techniques for quantitative anal3rsis for many additives and some hydrocarbon types are available, although few have been issued as ASTM standards. Reports on new methods are commonly reported in the chemistry literature. To locate information on new analytical methods, a most useful reference is the bi-aimual Application Review published by the American Chemical Society. These have appeared recently in the June 15 issue of Analytical Chemistry in odd-numbered years. Recent reviews cover coal, crude oil, shale oil, heavy oils (natural and refined), lubricants, natural gas, and refined products and source rocks. Extensive references to original research papers are provided. A complimentary Fundamental Review covering the basic analytical techniques is published in even-numbered years. 

Although the Hiickel method has now been supplanted by more complete treatments for theoretical analysis of organic reactions, the pictures of the n orbitals of both linear and cyclic conjugated polyene systems that it provides are correct as to symmetry and the relative energy of the orbitals. In many reactions where the n system is the primary site of reactivity, these orbitals correctly describe the behavior of the systems. For that reason, the reader should develop a familiarity with the qualitative description of the n orbitals of typical linear polyenes and conjugated cyclic hydrocarbons. These orbitals will be the basis for further discussion in Chapters 9 and 11. 

It is interesting that a bituminous coal (Sample 4) gave organic acids qualitatively similar to those of lignite coal see Figure Id). Major identified compounds were p-hydroxybenzoic acid and two isomers of hydroxybenzenedicarboxylic acid, benzene di- and tricarboxylic acids. No ortho or meta isomer of hydroxybenzoic acid was detected. We have found that solvent-extractable hydrocarbons obtained from this raw coal consist mainly of n-alkanes (Cjj to 3 ). This is quite different from other results which showed that aromatic hydrocarbons were the major solvent-extractable material of several bituminous and anthracite coals (21). Indeed, petrographic analysis shows that this coal has a high content of sporinite (14.3 wt %) and a low content of vitrinite (30.2 wt %) (33). 

Carbonyl complexes TM(CO) are a good starting point for a bonding analysis of TM compounds because they can be considered as a parent system for TM complexes in the same way as hydrocarbons are used as parent compounds for organic molecules. Figure 7.5 shows a qualitative description of bonding between a TM and a CO in terms of the DCD model as it is found in many chemistry textbooks. The main bonding contributions come from the electron donation of the CO a HOMO into an empty d(o) orbital of the metal and the backdonation from occupied d(it) orbitals of the metal into the unoccupied it -orbital of CO. 

Chlorosulfonic acid is widely used in organic qualitative analysis to prepare solid derivatives from liquid or low melting aromatic compounds, e.g. hydrocarbons, halides and ethers." The procedure involves conversion of the aromatic compound into the sulfonyl chloride, which is subsequently reacted with ammonia to yield the solid sulfonamide derivative which is suitable for melting point determination, Chlorosulfonic acid reacts with carboxylic acid anhydrides to give excellent yields of the acid chlorides (Equation 11). 

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