Aromaticity homologs

Quinoxalinone and acetone gave 3-acetonyT2( 1 //)-quinoxalinone (41) [Me2SC>4 (as catalyst), reflux until complete by tic 91% aerial aromatization ) homologs likewise.572 cf 335 431... 

Once the alcohol or at least the cluster contains a soft ionization or fluorescence chromophore, a wide range of experimental tools opens up. Experimental methods for hydrogen-bonded aromatic clusters have been reviewed before [3, 19, 175]. Fluorescence can sometimes behave erratically with cluster size [176], and short lifetimes may require ultrafast detection techniques [177]. However, the techniques are very powerful and versatile in the study of alcohol clusters. Aromatic homologs of ethanol and propanol have been studied in this way [35, 120, 121, 178, 179]. By comparison to the corresponding nonaromatic systems [69], the O—H - n interaction can be unraveled and contrasted to that of O—H F contacts [30]. Attachment of nonfunctional aromatic molecules to nonaromatic alcohols and their clusters can induce characteristic switches in hydrogen bond topology [180], like aromatic side chains [36]. Nevertheless, it is a powerful tool for the size-selected study of alcohol clusters. 

The combination of [IrCl(cod)Cl]2 complex with P(t-Bu)3 efficiently catalyzes aromatic homologation using internal alkyne [70]. For example, the reaction of benzoyl chloride 153 with 4-octyne 154 afforded 1,2,3,4-tetrapropylnaphthalene 155 (Equation 10.41). The reaction with 2-thenoyl and 2-naphthoyl chlorides also affords benzothiophene and anthracene, respectively, in high yields. The reaction would proceed as follows (Scheme 10.9) (i) oxidative addition of aroyl chloride... 

Hesse S, Suhm MA (2009) Conformation and aggregation of proline esters and their aromatic homologs pyramidal vs. planar RR N-H in hydrogen bonds. Z Phys Chem 223 579... 

Benzene and its purely aromatic homologs (naphthalene, etc.) do not appear to react with iron carbonyls though iron carbonyl complexes can be obtained from several other aromatic systems. For example, the reaction of m- and -divinylbenzenes (LII, LIII) with Fc3(CO)i2 leads to the formation of m- and -divinylbenzene-diiron hexacarbonyl complexes (36). No analogous metal complexes were obtained from styrene or vinyltoluenes. The two divinyl complexes are stable crystalline solids and, as far as their structure is concerned, it has been suggested that in each case a vinylic bond and two pairs of ir electrons from the benzene ring are used to bond to each of two Fe(CO)3 groups (36). 

The extent of octane number change with changes in molecular configuration is shown in Table 15.8, where normal paraffins and naphthenes are compared with their aromatic homologs. 

It is of particular interest to be able to correlate solubility and partitioning with the molecular stmcture of the surfactant and solute. Likes dissolve like is a well-wom plirase that appears applicable, as we see in microemulsion fonnation where reverse micelles solubilize water and nonnal micelles solubilize hydrocarbons. Surfactant interactions, geometrical factors and solute loading produce limitations, however. There appear to be no universal models for solubilization that are readily available and that rest on molecular stmcture. Correlations of homologous solutes in various micellar solutions have been reviewed by Nagarajan [52]. Some examples of solubilization, such as for polycyclic aromatics in dodecyl sulphonate micelles, are driven by hydrophobic... 

Two methods may conveniently be used to ascend the homologous series of aromatic hydrocarbons ... 

A useful reaction sequence has been developed for conversion of an aromatic aldehyde into the next higher homologous acid. The nitro analog of 45, prepared from m-nitrobenzaldehyde, is converted into the azide 51 by hydrazinolysis and treatment with nitrous acid. The... 

The fact that many 4 systems are paratropic even though they may be nonplanar and have unequal bond distances indicates that if planarity were enforced, the ring currents might be even greater. That this is true is dramatically illustrated by the NMR spectrum of the dianion of 83 (and its diethyl and dipropyl homologs). We may recall that in 83, the outer protons were found at 8.14-8.67 8 with the methyl protons at —4.25 8. For the dianion, however, which is forced to have approximately the same planar geometry but now has 16 electrons, the outer protons are shifted to about -3 8 while the methyl protons are found at 21 8, a shift of 258 We have already seen where the converse shift was made, when [16]annulenes that were antiaromatic were converted to 18-electron dianions that were aromatic. In these cases, the changes in NMR chemical shifts were almost as dramatic. Heat of combustion measurements also show that [16]annulene is much less stable than its dianion. 

Homologous series of simple hydrocarbons aromatic hydrocarbons... 

Microautoclave data was also obtained with Wilsonville Batch I solvent utilizing Indiana V coal. Batch I solvent was obtained from Wilsonville in mid-1977. Other batches of recycle solvent were received later. Batch I solvent had inspections most like the Allied 24CA Creosote Oil used for start-up at the Wilsonville Pilot Plant. Succeeding batches of solvent received by CCDC showed substantial differences, presumably due to equilibration at various operating conditions. As the Wilsonville solvent aged and became more coal derived, the solvent aromaticity decreased with an increase in such compounds as indan and related homologs. The decrease in aromaticity has also been verified by NMR. A later solvent (Batch III) also showed an increase in phenolic and a decrease in phenanthrene (anthracene) and hydrogenated phenanthrene (anthracene) type compounds. 

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