Carbon bonding properties

You have already had considerable experience with carbanionic compounds and their applications in synthetic organic chemistry The first was acetyhde ion m Chapter 9 followed m Chapter 14 by organometallic compounds—Grignard reagents for example—that act as sources of negatively polarized carbon In Chapter 18 you learned that enolate ions—reactive intermediates generated from aldehydes and ketones—are nucleophilic and that this property can be used to advantage as a method for carbon-carbon bond formation... 

The chemical properties of isopentenyl pyrophosphate and dimethylallyl pyrophosphate are complementary m a way that permits them to react with each other to form a carbon-carbon bond that unites two isoprene units Using the tt electrons of its double... 

Chemical Properties. The most impoitant reactions which tetraorganotins undergo are heterolytic, ie, electrophilic and nucleophilic, cleavage and Kocheshkov redistribution (81—84). The tin—carbon bond in tetraorganotins is easily cleaved by halogens, hydrogen hahdes, and mineral acids ... 

Properties of zinc salts of inorganic and organic salts are Hsted in Table 1 with other commercially important zinc chemicals. In the dithiocarbamates, 2-mercaptobenzothiazole, and formaldehyde sulfoxylate, zinc is covalendy bound to sulfur. In compounds such as the oxide, borate, and sihcate, the covalent bonds with oxygen are very stable. Zinc—carbon bonds occur in diorganozinc compounds, eg, diethjizinc [557-20-0]. Such compounds were much used in organic synthesis prior to the development of the more convenient Grignard route (see Grignard reactions). 

The view has also existed in the past that the carbon-silicon bond should be similar in behaviour to the carbon-carbon bond and would have a similar average bond energy. There is some measure of truth in the assumption about average bond energy but because silicon is more electropositive than carbon the C—Si bond will be polar and its properties will be very dependent on the nature of groups attached to the carbon and silicon groups. For example, the CH3—Si group is particularly resistant to oxidation but H13—Si is not. 

Table 1. Some properties of carbon-carbon bonds...

Difluorobutane contains two chiral atoms, and can exist as any one of three stereoisomers. Predicting the properties of these molecules is complicated due to the fact that each exists as a mixture of three conformers because of rapid internal rotation about the central carbon-carbon bond. 

Alkane Hydrocarbon containing only single carbon-carbon bonds. The simplest example is methane, CK, 580 cis-trans isomer in, 598 isomers in, 580-582 nomenclature, 582t physical properties, 591t sources, 583-585 structural isomerism, 597 tests for, 602 uses, 583-585... 

Whichever symbol is used, (SO), (SI), or (32), the chemist always remembers that the carbon-carbon bonds are actually all the same and that they have properties unlike either simple double bonds or simple single bonds. 

Unfortunately, at present the information characterizing the properties of the active bond in polymerization catalysts is very scant. The analogy between the features of the active bonds in the propagation centers and those of the transition metal-carbon bond in individual organometallic compounds is sure to exist, but as in the initial form the latter do not show catalytic activity in olefin polymerization this analogy is restricted to its limits. 

Two other important properties of silicon-carbon bonds are that carbonium ions fl and carbanions (or metalloid equivalents) a to silicon are favoured over alternatives, i.e. that situations involving Si—C—C+ and Si—C are thermodynamically relatively good. 

What Are the Key Ideas The large numbers of different hydrocarDons arise from the ability of carbon atoms to form long chains and rings with one another the types of carbon-carbon bonds that are present give the hydrocarbons characteristic properties. 

Because the types of carbon-carbon bonds present in the molecule tend to dominate its properties, an aliphatic hydrocarbon is first classified as an alkane, alkene, or alkyne. Then the longest chain of carbon atoms is used to form the root of the name. Other hydrocarbon groups attached to the longest chain are named as side chains. 

The synthesis and properties of the tin-carbon bond were reviewed in reference (35). Three recent volumes of Gmelin, written by H. Schumann and I. Schumann, comprehensively cover the literature, up to the end of 1973, on tetraalkyltin compounds R Sn (36), RaSnR (37), and RtSnR, RjSnR R", and RR SnR"R " (38), and are invaluable sources of reference. 

---