Singly Bonded Cyclic Compounds

Theoretical aspects of organosilicon compounds C. Singly Bonded Cyclic Compounds 

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Solution The first ringed compound has six carbon atoms and they are joined by single lines indicating all single bonds. This compound is called cyclohexane. The same holds true for the second compound except it has eight carbon atoms. Its name will be cycloctane. Both of these cyclic hydrocarbons can be found in Figure 11.5. 

B. Larger Non-cyclic Singly Bonded Silicon Compounds... 

The bicyclic compound 8.17 also serves as a source of the five-membered ring 8.20 upon reduction with SbPhs. In contrast to the related S or Se systems, 8.11a and 8.11b, both Cl substituents are attached covalently to Te in 8.20. Reaction of 8.20 with an excess of AsFs in SO2 produces the eight-membered cyclic [Tc2S2N4] dication, which exhibits a Te-Te bond length of 2.88 A (cf. 2.70 A for a Te-Te single bond) and no transannular S S bonding J... 

Compounds that contain only hydrogen and carbon are called hydrocarbons. The hydrocarbons that have only single bonds all have similar chemistry and they are called, as a family, the saturated hydrocarbons. If there are carbon-carbon double bonds, the reactivity is much enhanced. Hence hydrocarbons containing one or more double bonds are named as a distinct family, unsaturated hydrocarbons. Both saturated and unsaturated hydrocarbons can occur in chain-like structures or in cyclic structures. Each of these families will be considered. 

We have already remarked that ethane is a member of a family of compounds called the saturated hydrocarbons. This term identifies compounds that contain only carbon and hydrogen in which all bonds to carbon are single bonds formed with hydrogen or other carbon atoms. They occur in chains, branched chains, and cyclic structures. 

In open chain compounds that lack any chiral centre of course, rotation about all single bonds can be assumed to be both relatively free and fast on the NMR timescale and the 7-9 Hz range quoted is the result of averaging of this angle. The same is of course not true in cyclic systems where structures are rigid and bond angles constrained. We will deal with this topic thoroughly in Section 6.6.5. 

This group of compounds includes those monomers with one or more carbon atoms carrying a hydroperoxy or peroxy group, and also singly bonded to an oxygen atom present as hydroxyl, ether or cyclic ether functions. While the group of compounds is, in general, moderately stable, the lower 1-hydroxy and 1,T-dihydroxy-alkyl peroxides or hydroperoxides are explosive. Individually indexed compounds are ... 

We know today that benzene is a cyclic compound with the equivalent of three double bonds and three single bonds, as shown in Figure 1.9(A). However, the electrons that form the double bonds in benzene are spread out and shared over the whole molecule. Thus, benzene actually has six identical bonds, each one half-way between a single and a double bond. These bonds are much more stable than ordinary double bonds and do not react in the same way. Figure 1.9(B) shows a more accurate way to represent the bonding in benzene. Molecules with this type of special electron sharing are called aromatic compounds. As mentioned earlier, benzene is the simplest aromatic compound. 

The cyclizahon of amino alcohols should be an attractive method for the synthesis of N-heterocyclic compounds, mainly because they can be obtained in a single step and without the generation of wasteful byproducts. Carbon-nitrogen bond formation catalyzed by Cp lr complexes has been extended to the synthesis of N-hetero-cyclic compounds by the cyclization of amino alcohols. 

Use ball-and-stick models or suitable three-dimensional drawings to determine which members of the following sets of formulas represent identical compounds, provided free rotation" is considered to be possible around all single bonds (except when these bonds are present in a cyclic structure) ... 

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