Other Carbon Compounds

Carbon Monoxide.—Some examples of carbon monoxide insertion (alkyl migrations) have been mentioned in the discussion of carbonylation and hydroformylation reactions in the previous chapter (Part IV, Chapter 3, Section 10). The remaining reports will be treated here in Periodic Table order. 

Molybdenum, a -Bromoallenes, e.g. (6), react with the [Mo(CO)s-(A -CsHj)]- anion, in tetrahydrofuran solution, to produce the new series 

R migration) step, and finally bonding of the allene moiety to the molybdenum. The last step can be prevented by addition of a phosphine, which bonds to the metal to prevent co-ordination of the allene double-bond.  

The mechanism of formation of the compounds (8) is analogous to that outlined for the molybdenum series (7) above.  

An extensive kinetic study of the carbonyl insertion, or alkyl migration, reaction 

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Just as in the case for the hydrosphere, the atmosphere participates in all of the major biogeochemical cycles (except for phosphorus). In turn, the chemical composition of the atmosphere dictates its physical and optical properties, the latter being of great importance for the heat balance of Earth and its climate. Both major constituents (O2, H2O) and minor ones (CO2, sulfur, nitrogen, and other carbon compounds) are involved in mediating the amounts and characteristics of both incoming solar and outgoing infrared radiation. 

Compounds with a low HOMO and LUMO (Figure 5.5b) tend to be stable to selfreaction but are chemically reactive as Lewis acids and electrophiles. The lower the LUMO, the more reactive. Carbocations, with LUMO near a, are the most powerful acids and electrophiles, followed by boranes and some metal cations. Where the LUMO is the a of an H—X bond, the compound will be a Lowry-Bronsted acid (proton donor). A Lowry-Bronsted acid is a special case of a Lewis acid. Where the LUMO is the cr of a C—X bond, the compound will tend to be subject to nucleophilic substitution. Alkyl halides and other carbon compounds with good leaving groups are examples of this group. Where the LUMO is the n of a C=X bond, the compound will tend to be subject to nucleophilic addition. Carbonyls, imines, and nitriles exemplify this group. 

OTHER CARBON COMPOUNDS—IN ADDITION TO NUMEROUS OTHER KINDS OF CARBON COMPOUNDS. THE MAIN GROUPS ILLUSTRATED ABOVE, THERE ARE MANY HAVE VERY COMPLICATED FORMULAS. 

In examining routes of biosynthesis it is helpful to identify some key intermediates. One of these is 3-phosphoglycerate. This compound is a primary product of photosynthesis and may reasonably be regarded as the starting material from which all other carbon compounds in nature are formed. Phospho-... 

Other carbon compounds make use of two alternative hybridization schemes. The 5 AO can form hybrids with two of the p AO s to give three sp hybrid orbitals, with one /r-orbital remaining unhybridized. This accounts for the structure of ethylene (elhcne) ... 

The same reaction can be used with steam and other carbon compounds. For example, using methane, or natural gas (CFT), the reaction is ... 

Which class of compounds forms the basis for naming most other carbon compounds ... 

For the years 1855 to 1908, inclusive, illustrated abridgments were issued in 146 classes. Chemical patents appear in Class 1, Acids, alkalies, oxides, and salts, inorganic, and in Class 2, Acids and salts, organic, and other carbon compounds (including dyes). Chemical patents will also be found in classes dealing with other subjects Table I gives the classes under which the listed subject was classified. 

All caustobolites, however, contain carbon, hydrogen and oxygen even though in different proportions for different caustobolites. Specifically, petroleum is a complex mixture of hydrocarbons and other carbon compounds. At the elemental level, it consists of elements such as carbon (84-87%) and hydrogen (12-14%) as well as oxygen, nitrogen and sulfur (1-2%). The sulfur content can sometimes be up to 3-5%. Overall, petroleum consists of hydrocarbons, asphaltenes and resins, paraffins, sulfur and ash. There are three main groups of hydrocarbons in petroleum—namely, paraffinic, naphthenic and aromatic hydrocarbons [2]. 

The other carbon compounds may be regarded as derived from the hydrocarbons by the substitution or addition of an atom or group of atoms in or upon the hydrocarbon, the character, or function of the substance so produced depending upon the character and position of the substituted or added atom or group.. This will be developed as we proceed. 

It is now possible to return to the case of carbon. As mentioned above, it is certain that carbon forms four bonds in many of its compounds. The outer electron configuration of carbon is 2s 2p. If one electron is promoted firom the filled 2s orbital into the empty p orbital, sp hybrid orbitals are possible. Calculation shows that the resulting four bonds will point towards the comers of a tetrahedron, at angles of 109° to each other (Figure 2.16). These angles are the tetrahedral angles found for methane, CH4, carbon tetrachloride, CCLi and many other carbon compounds. 

The question of adaptation to new sources of material, such as fresh sugars or other carbon compounds, presents some interesting aspects. The simplest mode of approach to the problem is to make the natural supposition that the multitudinous enzymatic reactions of the cell depend upon varying combinations of quite simple unit processes, a good deal of their specificity residing in the mode of combination, that is in the order of the unit steps, and in the extent to which each is needed for the particular synthetic sequence to be followed. Suppose cells are transferred to a new medium where substantially the same enzymes are used in a different way, for example a reducing enzyme which played a minor role in the old scheme may be involved in a key step in the new. The parts played by enzymes 1 and 2 in the old sequence are now taken over hyj and k, i.e. these latter become 1 and 2 of the new sequence. 

Inside the plant, the glucose is converted to starch, proteins and other carbon compounds that are needed for roots, stems and leaves. For proteins die plant also needs nitrogen, and small amounts of sulphur, which it obtains from the soil. 

Figure 1-18 Hybridization in carbon to create four sp hybrids. The resulting bonding gives CH4 and other carbon compounds tetrahedral stmctures. The sp hybrids contain small back lobes of sign opposite that of the front iobes. In analogy to Rgure 1 -16B, the energy diagram of -hybridized carbon contains four singly occupied, equal-energy sp levels, in addition to the filled Is orbital.

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