Unsaturated oxygen-containing compounds

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

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. 

In fact, the importance of the cationic photopolymerization lies beyond epoxides (39). Many oxygen-containing compounds, e.g., vinyl ethers, tetra-hydrofuran, oxetane, lactones, trioxane, and some unsaturated compounds (Fig. 3) can be polymerized by the same mechanism to form adhesives or coating materials. Crivello (43) reviews the scope of cationic photopolymerization, providing us with a perspective on this promising process. 

In flames of alaphatic hydrocarbons (also oxygen-containing compounds such as ethanol) unsaturated (usually alaphatic) hydrocarbons of higher molecular weight than the initial fuel molecule are found. With benzene (and presumably other aromatic hydrocarbon flames) derivatives such as napthalene, indene, etc., are formed. All of these intermediates disappear by the end of the primary reaction zone with the exception of the polyacetylenes (C2 H2). They (the polyacetylenes) are formed relatively late in the primary reaction zone and in the case of alaphatic hydrocarbons acetylene is their precursor. The concentration measurements indicated that in this region the polyacetylenes were in equilibrium with one another, hydrogen, and acetylene, e.g.. 

Hydroformylation is the reaction of an unsaturated compound (or a saturated compound which may generate an unsaturated compound) with carbon monoxide and hydrogen to yield an aldehyde. The reaction was discovered by O. Roelen in the laboratories of Ruhrchemie AG, Oberhau-sen-Holten in 1938 [21-23] when he tried to recycle olefins to the Fischer-Tropsch synthesis reactor. As reaction products he isolated oxygen-containing compounds which proved to be aldehydes and ketones. Roelen started extensive investigations with ethylene and obtained propionalde-hyde and diethylketone as main products. 

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]. 

A 1.1 Technically, the bromine number is the number of grams of bromine reacting with 100 g of the sample under prescribed conditions. By this definition, bromine consumed by addition, substitution, oxidation, and reactions with sulfur, nitrogen, and oxygen-containing compounds is included in the bromine number of the material. The use of the bromine number under determination in the estimation of olefinic unsaturation depends on the fact that the addition reaction proceeds rapidly and completely under most conditions. The addition of bromine proceeds readily at temperatures down to or below 0 C. Decreasing temperature of reaction, time of contact, and concentration of free bromine... 

Conjugation of the 7t-electrons of the carbon-carbon double bond with the LUMO sulfur 3d-orbitals would be expected to stabilize the Hiickel 4n -I- 2 (n = 0) array of n-electrons in the thiirene dioxide system. No wonder, therefore, that the successful synthesis of the first member in this series (e.g. 19b) has initiated and stimulated several studies , the main objective of which was to determine whether or not thiirene dioxides should be considered to be aromatic (or pseudo-aromatic ) and/or to what extent conjugation effects, which require some sort of n-d bonding in the conjugatively unsaturated sulfones, are operative within these systems. The fact that the sulfur-oxygen bond lengths in thiirene dioxides were found to be similar to those of other 802-containing compounds, does not corroborate a Hiickel-type jr-delocalization... 

Catalysts suitable specifically for reduction of carbon-oxygen bonds are based on oxides of copper, zinc and chromium Adkins catalysts). The so-called copper chromite (which is not necessarily a stoichiometric compound) is prepared by thermal decomposition of ammonium chromate and copper nitrate [50]. Its activity and stability is improved if barium nitrate is added before the thermal decomposition [57]. Similarly prepared zinc chromite is suitable for reductions of unsaturated acids and esters to unsaturated alcohols [52]. These catalysts are used specifically for reduction of carbonyl- and carboxyl-containing compounds to alcohols. Aldehydes and ketones are reduced at 150-200° and 100-150 atm, whereas esters and acids require temperatures up to 300° and pressures up to 350 atm. Because such conditions require special equipment and because all reductions achievable with copper chromite catalysts can be accomplished by hydrides and complex hydrides the use of Adkins catalyst in the laboratory is very limited. 

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. 

Many studies relative to the obtaining of oxygen-containing products, starting from a wide variety of unsaturated compounds, in different solvents, have been mainly realized by Criegee and some other authors [5-12] and the mechanism he proposed is outlined in Scheme 1. 

---