Hydroaromatic compound

A. von Baeyer (Munich) advancement of organic chemistry and the chemical industry through work on organic dyes and hydroaromatic compounds. 

Dehydrogenation (the conversion of alicycllc or hydroaromatic compounds into their aromatic counterparts by removal of hydrogen and also, in some cases, of other atoms or groups) finds wide application in the determination of structure of natural products of complex hydroaromatic structure. Dehydrogenation is employed also for the s)mthesis of polycyclic hydrocarbons and their derivatives from the readily accessible synthetic hydroaromatic compounds. A very simple example is the formation of p-methylnaphthalene from a-tetra-lone (which is itself prepared from benzene—see Section IV, 143) ... 

A wide range of isomers will be formed from the rearrangement of hydroaromatic compounds. 

P. W. Rabideau (Ed.) The Conformational Analysis of Cyclohexenes, Cyclohexadienes and Related Hydroaromatic Compounds, VCH, New York, 1989. 

In summary, the most popular hydrogen donors for the reduction of ketones, aldehydes and imines are alcohols and amines, while cyclic ethers or hydroaromatic compounds are the best choice for the reduction of alkenes and alkynes. 

DDQ was first introduced for the dehydrogenation of hydroaromatic compounds, such as tetralin and bibenzyl, which yield naphthalene and stilbene, respectively. A benzene ring or an olefinic bond provides sufficient activation, although it is sometimes difficult to force the reaction to completion. Phis high-potential quinone has since found wide a )plication, jiarticularly... 

Adolf von Baeyer Germany organic dyes and hydroaromatic compounds... 

More informative, perhaps, are the marked differences in relative FI signal intensities between the mass spectra shown in Figures 2c and 2d. In agreement with the previously mentioned results reported by Chakravarty et al (15) and Yun et al (16). the mass spectra of the low temperature component (Figures 2b and c) appear to be dominated by homologous series of aromatic and hydroaromatic compounds. Chemical identification of many of the compounds up to MW 350 has been accomplished by high resolution GC/MS (19, 20). although precise identification of the many possible isomeric structures involved will have to await the availability of suitable reference compounds. 

Palladium is the most active and most frequently used catalyst in transfer hydrogenations.77 78 Cyclohexene, a cheap, readily available, highly reactive molecule, is the preferred donor compound. Alternatively, tetralin and monoterpenes and, in general, any hydroaromatic compound, may be used. Mainly alcohols are employed as the donor with Raney Ni. 

Intensity measurements using rapid-passage dispersion mode spectra have been little explored to date. It became necessary, therefore, to study the quantitative aspects of C13 NMR. Our early work was limited to measurements on alkyl aromatic and hydroaromatic compounds. The results of intensity measurements on the C13 spectra of 15 compounds are illustrated graphically in Figure 2. Each point is the average of measurements on at least eight spectra, four of which were obtained with sweep increasing and four... 

Table 4.57 13C Chemical Shifts of Selected Benzocycloalkenes [396]a, Hydroaromatic Compounds [73e, 394, 397] and [2,2]Cyclophanes [398] (r5c in ppm).

Methylnaphthalene. This preparation illustrates the general procedure for catalytic dehydrogenation. The apparatus used is shown in Fig. 6.1. Heat a mixture of 3.2 g (0.02 mol) of the above hydroaromatic compound with 0.3 g of palladised charcoal (Section 4.2.54, p. 452) at 250-270 °C in a slow current of dry carbon dioxide in a Silicone oil or fusible metal bath for 3 hours (1). Cool, dissolve the residue in ether and filter off the catalyst. Wash the extract with dilute aqueous sodium hydroxide and dry it over anhydrous sodium sulphate. Remove the ether and distil the residual oil under reduced pressure use a small-scale distillation apparatus (cf. Fig. 2.111). Collect the 1-methylnaphthalene, b.p. 121-123 °C/20mmHg. The yield is 2.5g (89%). 

The reactivity pattern for the reduction of fluorenone—sporinite > vitrinite > alginite > semifusinite > fusinite > resinite—defines a bell shaped dependence on the H/C ratio of the maceral and presumably reflects the quantity of readily oxidized hydroaromatic compounds in the maceral. The differences in the effectiveness of the macerals depends in part upon their ability to initiate the reduction of the ketone and in part upon the facility with which they undergo oxidation. 

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