Pure macerals

Figure 2. Unpaired spin concentration in pure macerals...

Marie-Therese Mackowsky I would like to make a suggestion. In Germany, France, Belgium, and Holland we have a so-called central store for pure macerals. This is the laboratory of Dr. Kroger. Consequently, we have a maceral bank, and we can ask Prof. Kroger to send us a few grams of vitrinite, exinite, or micrinite. Perhaps you could have the same here, located perhaps at Pennsylvania State University. 

Table III. The Influences of Certain Coals and Pure Macerals on the Deuterium-Hydrogen Exchange Reaction of Tetralin-d 2 an( Diphenylmethane at 400°C.a...

The exinites isolated from PSOC-106, 828, and 1103 are relatively rich in sporinite, Table II. For comparison, we examined the resinite isolated from a Hiawatha coal. The exchange datum for this pure maceral, Table III, indicates that it is a significantly less effective agent for the promotion of the exchange reaction than the sporinite-rich macerals isolated from the other samples in spite of the fact that the whole Hiawatha coal is more reactive than the other whole coals. 

The distribution of the inertinite and liptinite within vitrinite of the coal particle—a particle composed of only a pure maceral or distinctive gains of macerals will have different plastic properties (and therefore coke/char morphology) than a particle where the inertinite and/or liptinite is distributed throughout the vitrinite. 

In the older method, still used in some CIS and East European tar refineries, the naphthalene oil is cooled to ambient temperatures in pans, the residual oil is separated from the crystals, and the cmde drained naphthalene is macerated and centrifuged. The so-called whizzed naphthalene crystallizes at ca 72—76°C. This product is subjected to 35 MPa (350 atm) at 60—70°C for several minutes in a mechanical press. The lower melting layers of the crystals ate expressed as Hquid, giving a product crystallizing at 78—78.5°C (95.5—96.5% pure). This grade, satisfactory for oxidation to phthaHc anhydride, is referred to as hot-pressed or phthaHc-grade naphthalene. 

For example, Beynon and Cwm coals when digested in anthracene oil give extraction yields of 68% and 47% respectively. This variation can be explained by reference to the maceral composition of the coals. Beynon coal contains a lower concentration of inertinite than the Cwm coal (Table V). In experiments where relatively pure samples of petrographic species were digested in anthracene oil, exinite and vitrinite were shown to be highly soluble, whilst in comparison the inertinite was almost completely insoluble. Similar variations in reactivity of macerals have been reported from studies of solubility in pure organic solvents (1(3). 

The iridoids, plumericin, isoplumericin, plumieride and fulvoplumierin, were present in the extracts of Plumeria rubra bark. After maceration of the powdered bark (3.5 kg) with dichloro-methane/methanol (1 1) and pure methanol, the combined extracts were partitioned between water and ethyl acetate. To isolate the four iridoids, the organic layer was chromatographed twice in a column using silica gel and gradient of increasing polarity with hexane and ethyl acetate, ethyl acetate and methanol, and then pure methanol. The amounts of the compounds isolated were not reported [75]. 

Separating the three macerals from the dull coal was difficult. The petro-graphical purity of the exinite is 86% and that of the micrinite 94%. For both macerals, vitrinite is the main impurity. Since the vitrinite has a petrographi-cal purity of 99%, it is not difficult to calculate the values for the pure exinite and pure micrinite from the experimental data on the highly enriched maceral fractions. All values reported in the tables are corrected ones. Table I summarizes the results of elementary analysis (maf) and the percentage of volatile matter. 

Peter H. Given Whereas Tschamler and Fuks, and Peover studied more or less pure vitrinites, Mazumdar apparently worked with whole coals. Moreover, Indian coals, being from Gondwanaland strata, are most probably of very different petrographic composition compared with European and North American coals (rich in exinites and inert macerals See p. 284). Quite apart from the question whether sulfur dehydrogenation really is free of side reactions, there may well be a spread of data at any level or rank because of petrographic differences. 

There has been available (or some years unarguable evidence that each of the major macerals groups has a distinct set of structural characteristics, and that the major macerals in any one coal do differ materially in chemical structure from each other. We must therefore admit that chemical structures alleged to represent whole coals are futile, and that basic chemical research should use single macerals in as pure a state as possible. On the other hand, some believe that pure vitrinite macerals at least can be represented usefully by a model structure. 

Marie-Therese Mackowsky We carried out maceral and microlithotype analyses. Besides these we determined the reflection of the pure vitrinites in oil. 

The preparation of maceral concentrates for study has been achieved by one of two approaches, either by hand picking or by a variety of techniques which exploit the variation in density between the various maceral groups. The first level of hand picking is the judicious sampling of lithotypes. This term is used to identify the various layers found in a coal seam. For humic coals there are four main designations of lithotypes vitrain, clarain, durain, and fusain (42). Vitrain bands are sources of fairly pure vitrinite group macerals while fusinite and semi-fusinite can be obtained from fusain. These are the... 

Dyrkacz and his coworkers have recently described a new procedure for the separation of coals into macerals (14). The macerals can be obtained in pure form, but only in limited quantity. Inasmuch as many of the methods used for the study of coal require relatively large amounts of material, we have undertaken new work on the development of small scale reactions for the accurate determination of the differences in chemical reactivity of macerals. The hydrogen transfer reactions are discussed in this report. Preliminary work revealed that very reproducible results could be obtained when 25 mg of a representative maceral was used as a catalyst for the hydrogen exchange reaction between tetra-... 

The maceral concentrates obtained by float-sink methods from PSOC-828 and 1103 were somewhat less pure than the macerals obtained by hand or by centrifugation. For convenient comparison, the data obtained in the exchange reactions have been normalized to 100% maceral purity on the basis of the petrographic information presented in Table II using simultaneous linear equations. The normalized results are summarized in Table IV. 

Maceration is the removal of substances by soaking materials in an appropriate liquid. Hot fat is used in maceration to extract essential oils from plant material. The saturated fat is then washed with alcohol to leave pure essential oil, e.g. calendula oil. Maceration is used for extraction of essential oils that cannot be extracted by distillation. 

Isolation of Starch.—Starch is also used as a food in its pure form. To obtain this the plant part, e.g., potatoes, corn, etc., is macerated and then stirred up with a large amount of water. The watery mass is passed through seives to remove the fibrous material while the starch, in suspension, passes through. On allowing the starchy liquid to settle the starch is obtained as a sediment in quite pure condition. As the materials used contain relatively little else than starch and water there is not much foreign substance present. Starch so prepared is the common form in which it is sold under the names of corn starch, and laundry starch, the former used as a food and the latter as a laundry sizing material. 

Most papers dealing with phenolic acid HPLC analysis in herbs describe only simple liquid extraction without the hydrolysis step. Acetone, methanol, or alcoholic-water or acetone-water mixtures are applied. Very rarely, pure water is used as the extraction solvent. " It was found that the extraction recoveries for water extracts are often lower in comparison to alcoholic-water mixtures, especially when the simultaneous separation of polar and less polar phenolic acids has been performed. Sometimes, the control of pH can improve the recovery. If necessary, n-hexane, chloroform, diethyl ether, benzene-acetone, petroleum ether, or other less polar solvents are recommended for removing interfering compounds. The extraction is usually performed by refluxing the samples for a specific time in a Soxhlet apparatus, with simple mechanical or magnetic stirring of the sample with the extraction solvent, or by plant sample maceration. The application of an ultrasonic bath for the liquid extraction has also become popular in recent years. The hydrolysis steps have also been recommended for medicinal species preparation, especially when other phenolic compounds are also analyzed simultaneously with phenolic acids in herbs. 

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