Unsaturated oxygen-containing

Coupled Cluster Method for Unsaturated Oxygen-Containing Compounds... 

The metathesis of olefins bearing functional groups provides potential routes to many valuable compounds. Metathesis catalysts, most of which contain a Lewis acid, are unfortunately poisoned by polar and basic compounds. As yet, only a few catalytic systems have proved to be active in metathesizing functionalized alkenes. In the homogeneous disproportionation of these substrates, the catalytic combination WCl —Sn(CH3)4 is still the best known [63]. In addition to its well known application in the conversion of unsaturated oxygen containing olefins, such as fatty acid esters and unsaturated ethers, its effectiveness for the homogeneous metathesis of unsaturated amines has also been described [64]. 

Concentrated sulphuric acid. The paraffin hydrocarbons, cych-paraffins, the less readily sulphonated aromatic hydrocarbons (benzene, toluene, xylenes, etc.) and their halogen derivatives, and the diaryl ethers are generally insoluble in cold concentrated sulphuric acid. Unsaturated hydrocarbons, certain polyalkylated aromatic hydrocarbons (such as mesitylene) and most oxygen-containing compounds are soluble in the cold acid. 

Table 12. Oxygen Index of Unsaturated Polyesters Containing Bromine ...

Table 14. Oxygen Index and Smoke Reduction of Unsaturated Polyester Containing Molybdenum Oxide and Antimony Oxide...

Pyrrole, the simplest five-membered unsaturated heterocyclic amine, is obtained commercially by treatment of furan with ammonia over an alumina catalyst at 400 °C. Furan, the oxygen-containing analog of pyrrole, is obtained by acid-catalyzed dehydration of the five-carbon sugars found in oat hulls and... 

Heterocyclic systems, such as the substituted indoline illustrated below,13 may also be constructed via cyclization of unsaturated organolithiums and a recent review of the preparation of nitrogen- and oxygen-containing heterocycles via this approach is available.14... 

Among the heterocyclic compounds, there are aromatic, e.g. pyridine, as well as nonaromatic, e.g. tetrahydrofuran, compounds. Similarly, there are saturated (e.g. tetrahydrofuran) and unsaturated (e.g. pyridine) heterocyclic compounds. Heterocycles also differ in their ring sizes, e.g. pyridine has a six-membered ring, whereas tetrahydrofuran is a five-membered oxygen-containing heterocyclic compound. 

An example of an unsaturated hydrocarbon containing a triple bond is acetylene, C2H2. A confined flame of acetylene burning in oxygen is hot enough to melt iron, which makes acetylene a choice fuel for the welding shown in Figure 12.10. 

NorrishJ has sought to connect the catalytic activity of surfaces with their polar nature. By polar nature is meant a certain chemical unsaturation, usually associated with the presence of oxygen in the molecule. His work on the combination of ethylene and bromine has already been mentioned. The combination hardly takes place at all in vessels coated with paraffin wax, but is promoted by surfaces of such oxygen-containing substances as cetyl alcohol and stearic acid. To be quite conclusive such observations would have to be combined with others showing that the actual adsorption on paraffin wax is not very... 

Compounds are said to be saturated when all the oxygen atoms of the parent anion are replaced by metallic acid anions unsaturated compounds contain some replaceable oxygen. 

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