Organic chemistry, dominance

With respect to research specialties, the largest proportion of interviewees concentrated in organic chemistry, followed by physical chemistry (Table 3.6). Few concentrated in analytical chemistry. There were some cohort differences. For example, organic chemistry dominated the specialties in Cohorts I (before 1955), III (1965-1974), and IV (1975-1984) while both organic chemistry and physical chemistry led Cohort II (1955-1964) and physical chemistry was the leading specialty of those earning doctorates in Cohort V (1985-1995). The cohort distribution of specialties is consistent with annual ACS survey data. In 2002, U.S. institutions awarded approximately 1,822 doctoral degrees in chemistry. Of... 

The reported structural chemistry of zinc aldehyde complexes is dominated by Vahrenkamp and co-workers. A systematic investigation is reported over three papers published in 1999. All X-ray structures reported in these papers are aryl aldehydes and no aliphatic aldehyde structures with zinc were found in the CSD. Zinc is frequently exploited in preparative organic chemistry and enzyme-catalyzed transformations of organic carbonyl compounds. 

Section 2.17). We shall find that it dominates much of life s organic chemistry too. There is also the rather unusual insolubility of VS4. We need to explain the presence of some V, Co, Ni and Zn in early life, but note that their sulfides are relatively soluble in somewhat acid solutions, pH < 7, which may have prevailed at least locally some 4 x 109 years ago. Molybdenum and heavy metals of Groups 13 to 16 are also insoluble as sulfides but tungsten does not precipitate so easily and is known to be more available than molybdenum in sulfide-rich seas. 

Let us now look at some further peculiarities common to organic chemistry (and cellular chemistry) but not so dominant in inorganic chemistry. 

The characteristics of s/p-orbital chemistry are associated, above all, with the atoms H, C, N, and O that dominate organic and biochemical phenomena. Hence, the discussion of bonding in s/p-block elements inevitably carries a bias toward organic chemistry, and toward the issues and controversies that continue to animate this most mature and advanced area of chemistry. Indeed, organic chemistry may be considered the cradle of covalency, where many principles of chemical bonding were first grasped and exploited. 

Ortho-Effect. The ortho-effect is one of the most widely known structural phenomena in organic chemistry. It is widely used in organic chemistry for synthetic purposes. The mass spectra of the majority of ort/jo-substituted aromatic compounds possess significant differences in comparison with the spectra of their meta- and para-isomers. A classic example of the ortho-effect in mass spectrometry involves fragmentation of alkylsalicylates. The intense peaks of [M - ROH]+ ions dominate in the El spectra of these compounds. These peaks are absent in the spectra of their meta- and para-isomers. The reaction leading to these ions may be represented by Scheme 5.12. 

Not coincidentally, the 1830s was the period when organic chemistry became a subfield or subdiscipline within chemical sciencebut a clearly dominant one, dealing with the material substances of biology and physiology,... 

The dominant tendency of my studies has been not so much to obtain and describe organic compounds but... to penetrate their mechanisms.. . . For undertaking this kind of problem, the classic methods of organic chemistry are far from sufficient. Physicochemical procedures become more and more necessary. I have been led to use especially optical methods (the Raman effect and ultraviolet spectra) and electrochemical techniques (conductibility, electrode potentials, and especially polarography).. . . The notion of reaction mechanism led almost automatically to envisioning the electronic aspect of chemical phenomena. From 1927, and working in common with Charles Prevost, I have directed my attention on the electronic theory of reactions." 56... 

By the second half of the nineteenth century German chemists had established a dominant position in analytical and synthetic organic chemistry. Various simple sugars and aminoacids were being isolated and characterized, as well as more complex plant products. Studies on the composition of blood and the properties of hemoglobin were also well under way. The composition of lipid-rich components and the order of the different units within complex macromolecules, such as proteins and nucleic acids, could not however be resolved by techniques then available. 

---