Isomers and Homologues

Despite the fact that the simple compounds in the figure have the same formula, their properties differ very significantly one from another. Dimethyl ether is a highly flammable gas at room temperature, whereas ethanol is a semiconsumable liquid at room temperature. Even though these two compounds have the same formula, the connectivity of the atoms results in very different properties. For an indication of how some structural isomers might be treated, let s briefly review the case of Ex parte Mowry, which concerned an appeal to the Board of Patent Examiners at the 

In contrast to chemical formula isomers, positional isomers are a narrower subclass where the compounds contain the same appending groups, but those groups may be connected in a different manner one from another. Positional isomers must have the same substituents, but those substituents occupy a different position on the molecule. 

FIGURE 8.17 Claimed compound and prior art compounds from 808 reference. 

62The applicant raised additional arguments for nonobviousness, which were not persuasive to the Court. One was that that the two prior art compounds had very different skin toxicities despite their similarity in 

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The structure implicates biochemical persistence, which was confirmed by FIA-MS and FIA-MS-MS(+) applying the pattern recognition and the CID approach. LC separation of this complex mixture of isomers and homologues under ion-pairing conditions, however, failed. APCI-LC-MS(+) resulted in broad, unresolved signals [37]. 

Both the extent and the kinetics of LAS biodegradation depend on the characteristics of the compound (e.g. isomer and homologue distribution, and the initial concentration), the properties of the medium... 

Initial LAS concentration, and isomer and homologue distribution Tests conducted with concentrations found in the natural environment (1 ppm) present percentages of primary biodegradation in excess of 99%, although when the initial concentration tested is higher (10-20 ppm), the extent is less (see Table 5.3.1). The rate of degradation also decreases in line with the initial concentration due to the toxic effect on the microbiota [29]. In Table 5.3.1 it can be observed that the average life-times increase in line with the increase in the initial concentration of LAS. 

Isomers and homologue variability in experimental BCFs of surfactants in two freshwater fish species, P. promelas and O. mykiss... 

Hollister LE Tetrahydrocannabinol isomers and homologues controlled effects of smoking. Nature 1970 227 968-969. 

Roberts, D.W., Application of QSAR to biodegradation of linear alkylbenzene sul-phonate (LAS) isomers and homologues, Sci. Total Environ., 109/110, 301-306, 1991. 

In general retrieval systems, additional information such as retention data may be required for a conclusive peak recognition using UV spectra [590]. For obvious reasons, however, retention data cannot be used as an aid for peak recognition for optimization purposes. Related solutes, such as isomers and homologues, may show similar spectra, which are hard to differentiate. In case of doubt, one may have to refer to peak areas for additional information. Again (see section 4.6.1), this requires very good resolution of the individual peaks. 

Except for 1 -monoCN, which is a liquid at room temperature, the chlorinated naphthalenes are crystalline compounds. The melting point increases with increasing chlorine substitution with considerable variation within each homolo-gue group, cf. Table 2. The commercial PCN products, which occur as complex mixtures of isomers and homologues, are generally waxes with high compatibility with other materials. The solid products melt to liquids of extremely low viscosity [1]. 

For a technical short chain chlorinated paraffin (SCCP) mixture containing 60% chlorine by weight, the theoretical number of congeners (defined as constitutional isomers and homologues) is 4,200 [11, 16]. It should be noted that the complexity would actually be an order of magnitude greater than that indicated in Table 1 because chlorine substitution at a secondary carbon atom usually produces a chiral carbon atom so that enantiomers and diastereoisomers would be generated. 

Mechoulam, Chemistry and Biochemistry of Cannabis," 76 75 L.E. Hollister, Tetrahydrocannabinol Isomers and Homologues Contrasted Effects of Smoking, Nature 111 (1970) 968 G.W. Kinzer et al., The Fate of the Cannabinoid Components of Marijuana During Smoking, Bulletin on Narcotics 26 (1974) 41 A.R. Patel and G.B. Gori, Preparation and Monitoring of Marijuana Smoke Condensate Samples, Bulletin on Narcotics 27 (1975) 47. 

Trimethylsilylation -g.c.-m.s. has been used for the determination of isosorbide-5-mononitrate (in which both the hydroxy- and nitro-functions are silylated) in human serum, modified nucleosides in human urine and zeatin and its riboside in plant tissues after separation by solid-phase extraction and h.p.l.c. fractionation. The g.c. analyses of sucrose pertrimethylsilylated monostearate isomers and homologues with different ac l chains have been investigated on packed columns. For the g.c.-m.s. of amino-containing nucleosides, the use of -dimethylaminomethylene-O-trimethylsilyl derivatives [as in compoimd (1)] has been advocated. The derivatives are formed by reaction with DMF dimethyl acetal follwed by silylation. ... 

The distinction of aliphatic isomers and homologues in crude oil and gasoline fractions by IR spectroscopy is a hard task. However, the method is very powerful if the identification of aromatic compounds in oil fractions is required. The discrimination ability of... 

Such sesquiterpene homologues seem plentiful, particularly in ants. The three farnesene homologues from the Dufour glands of Myrmica ants are an example (Figure 6.24). Their purpose there is unknown. In the Dufour gland of the ant Manica rubida nine isomers and homologues of farnesene were found. Their function is again unknown. 

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