Oxygen-containing groups

Selenium. The substance is heated with a large excess of selenium at 280-350° for 36-48 hours. Better yields (and less side reactions) are usually obtained than with sulphur, but, owing to the higher temperature, rearrangements are more likely. Oxygen-containing groups are particularly prone to elimination. 

Bivalent Sulfur. The prefix thio, placed before an affix that denotes the oxygen-containing group or an oxygen atom, implies the replacement of that oxygen by sulfur. Thus the suffix -thiol denotes — SH, -thione denotes —(C)=S and implies the presence of an =S at a nonterminal carbon atom, -thioic acid denotes [(C)=S]OH [(C)=0]SH (that is, the O-substituted acid and the 5-substi-... 

Among oxygen containing groups, a higher oxidation state takes precedence over a lower one in deter-rnining the suffix of the substitutive nane. Thus, a compound that contains both an alcohol and an aldehyde function is named as an aldehyde. 

If all the oxygen containing groups are reduced, n-hexane results. This test helps establish that the glucose molecule has a chain structure. One representation of the structural formula of glucose, C6Hi206, is... 

One way is by introducing oxygen-containing groups. Protocols employ oxidations with concentrated HNO3 or a mixture with H2SO4 under reflux [92-94]. 

The thallium intermediates can be useful in directing substitution to specific positions when the site of thallation can be controlled in an advantageous way. The two principal means of control are chelation and the ability to effect thermal equilibration of arylthallium intermediates. Oxygen-containing groups normally direct thallation to the ortho position by a chelation effect. The thermodynamically favored position is... 

Sometimes cis-trans isomerizations occur slowly or not at all because certain groups anchor their end of the double bond to the surface and inhibit that end from flipping. Thus, phenyl groups and oxygen-containing groups tend to inhibit cis-trans isomerization (Fig. 2.17).120... 

Figure 1.19 Tyrosine and phenylalanine residues can undergo oxidation to modify their phenyl side-chain groups. Tyrosine can form covalent dimers that link two side chains together via a radical reaction. Both tyrosine and phenylalanine can be modified by oxidation to add oxygen-containing groups directly to their aromatic ring.

This mechanism differs from the "carbide theory in that chain growth involves oxygen-containing groups and is thought to take place on the ultimate or penultimate carbon atoms of the longest chain by surface condensation reactions. 

Hontoria-Lucas C, Lopez-Peinado AJ, de D. Lopez-Gonzalez J, Rojas-Cervantes ML, Martfn-Aranda RM. Study of oxygen-containing groups in a series of graphite oxides Physical and chemical characterization, Carbon 1995, 33,1585-1592. 

The basicity of the carbon surface derives from the n electron decolization in graphite carbon layers and the antioxidant character of carbon forming oxygen-containing groups [180]. Delocalized n electrons are capable of nucleophilic attack giving Lewis basicity to the carbon [180,189]. 

Dogadkin, Skorodumova, and Kovaleva (127) studied the reaction of carbon black with sulfur at low temperatures. A solution in toluene was used at 145° in the presence of an accelerator. The sulfur sorption was negatively influenced by surface oxides. The oxygen-containing groups were not affected by the reaction, since no change in the water vapor adsorption was detected. No hydrogen sulfide was evolved under the reaction conditions. 

Two additional examples of amine nomenclature are shown in Figure 13-6. Note that in the p-aminobenzoic acid the oxygen-containing group takes precedence in the naming, so that the compound is then named as a substituted benzoic acid and not a substituted aniline, as is done in the N,N-dimethylaniline beside it. 

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