Naturally occurring materials

The actions of the naturally occurring materials now known as alkaloids were probably utilized by the early Egyptians and/or Sumarians (1). However, the beginnings of recorded, reproducible isolation from plants of substances with certain composition first took place in the early nineteenth century. Then in close succession, narcotine [128-62-1] (1, now called noscopine, C22H23NOy) (2) and morphine (2, R = H) (3) (both from the opium poppy, Papaver somnijerum E.) were obtained. 

Miscellaneous Pharmaceutical Processes. Solvent extraction is used for the preparation of many products that ate either isolated from naturally occurring materials or purified during synthesis. Among these are sulfa dmgs, methaqualone [72-44-6] phenobarbital [50-06-6] antihistamines, cortisone [53-06-5] estrogens and other hormones (qv), and reserpine [50-55-5] and alkaloids (qv). Common solvents for these appHcations are chloroform, isoamyl alcohol, diethyl ether, and methylene chloride. Distribution coefficient data for dmg species are important for the design of solvent extraction procedures. These can be determined with a laboratory continuous extraction system (AKUEVE) (244). 

Dosage forms of naturally occurring materials having therapeutic activity are prepared by extractive processes, especially percolation and maceration. Examples of such dosage forms have included certain tinctures, symps, fluid extracts, and powdered extracts. 

More recendy, asphalts have been defined as the manufactured materials that are produced during petroleum processing whereas bitumens have been defined as the naturally occurring materials (5,6). That is, petroleum and related materials can be divided into various class subgroups ... 

Refra.ctories, Refractory products are prepared from a wide variety of naturally occurring materials such as chromite [1308-31 -2] and magnesite [546-93-0] or from clays predominandy composed of kaolinite. Increasingly, higher purity synthetic materials are being used to obtain special properties. On the other hand, for many refractory uses, a somewhat lower fusion point than that provided by kaolinite may be adequate, so that clay materials having a moderate amount of other components as, for example, iUite, may be satisfactory. High alumina clays are also used extensively for the manufacture of special types of refractories. 

When this is done it is seen that in all cases plastics materials, before compounding with additives, consist of a mass of very large molecules. In the case of a few naturally occurring materials, such as bitumen, shellac and amber, the compositions are heterogeneous and complex but in all other cases the plastics materials belong to a chemical family referred to as high polymers. 

Non-elastomeric chemical derivatives of natural rubber are discussed in Chapter 30 in which chemically related naturally occurring materials such as gutta percha and balata are briefly considered. 

Greensands Naturally occurring materials, composed primarily of complex silicates, which possess ion-exchange properties. 

The structurally simplest steroids, the aromatic A ring estrogens, have ironically proven most difficultly accessible because this aromatic ring is not found in any of the plant sterols available in commercial quantities. The main task of partial synthesis from naturally occurring material thus becomes... 

Fibers in this category are composed of naturally occurring materials. A good example is asbestos. The most common type is chrysotile, representing more than 95% of world asbestos production. Chemically it is magnesium silicate (Mg6(OH)4 Si205). Today, use of this fiber is limited because long exposure to it may cause bronchial cancer. 

Heavy metals are present in drilled formation solids and in naturally occurring materials used as mud additives. The latter include barite, bentonite, lignite, and mica (sometimes used to stop mud losses downhole). There are background levels of heavy metals in trees that carry through into lignosulfonate made from them. 

Diverse thermogravimetric results can be obtained from samples with different pre-histories for example, TG and DTG curves showed that magnesium hydroxide prepared by precipitation methods has a different temperature of decomposition from that for the naturally occurring material.32 It follows that the source and/or the method of formation of the sample should be ascertained. 

Biomimetic materials are materials that are modeled after naturally occurring materials. Gels or flexible polymers (Chapter 19) modeled after natural membranes and tissues are biomimetic materials with remarkable properties. Some can be made to crawl on their own like tiny nanometer worms, others pulsate to an internally generated rhythm, and still others respond in seemingly lifelike ways to stimuli. 

Some of the potential uses of the fats and oils found in plants have been reviewed and some uses of carbohydrate-based polymers briefly discussed. Plants contain a whole variety of other chemicals including amino acids, terpenes, flavonoids, alkaloids, etc. When the potential for these naturally occurring materials are combined with the secondary products that can be obtained by fermentation or other microbial processes or by traditional chemical transformations, the array of chemicals that can readily be created from renewable resources is huge. In this section a few of the more interesting examples are considered. 

What convinces scientists that sustained fission once occurred at Oklo is the presence of characteristic fission products in the ore. Elements of mass numbers between 75 and 160 occur in the ore in larger amounts than elsewhere. Furthermore, mass analysis of the elements in Oklo ore shows that they are distributed in the characteristic pattern shown in Figure 22-12. This isotopic signature, which is not found in any other naturally occurring materials, is so characteristic that it has convinced most scientists that the ore deposits at Oklo once formed a huge nuclear reactor. 

The geological sciences are involved in studying the naturally occurring materials of the earth and solar system (i) to understand the fimdamental processes of crustal formation on earth and solar system evolution, and (2) to evaluate the crustal materials of potential economic value to man. Prior to the 1930 s, analyses were carried out exclusively using classical analytical techniques, with detection limits on the order of o.oi-o.i % (mass fraction). The number of elements contained in any sample could be as extensive as the periodic table, but very few of these could be determined. The development of instrumental techniques revolutionized the analysis of geochemical samples, beginning in the 1930 s. 

The revised database holds over 23 000 analyte values for 660 measurands and 1670 reference materials produced by 56 different producers, from 22 countries. The database is restricted to natural matrix materials (i.e. made from naturally occurring materials, excluding calibration standards manufactured from pure chemicals). Information has been extracted from the relevant certificates of analysis, information sheets, and other reports provided by the reference material producers. As a general rule, the authors have only included in the compilation reference materials for which a certificate of analysis or similar documentation is on file. Information included in the survey is on values for measurands determined in reference materials, producers, suppliers, the cost of the materials, the unit size supplied, and the recommended minimum weight of material for analysis, if available. The new searchable database has been designed to help analysts to select reference materials for quality assurance purposes that match as closely as possible, with respect to matrix type and concentrations of the measurands of interest and their samples to be analyzed see Table 8.3. 

The following intermediates in the synthesis of naturally occurring materials have been synthesized by reactions based on a benzyne intermediate. The benzyne precursor is shown. By retrosynthetic analysis identify an appropriate co-reactant that would form the desired compound. 

Biomaterials are synthetic and naturally occurring materials that are foreign to the body but are used to replace a diseased organ or tissue or augment or assist a partially functioning organ or tissue. Cardiovascular, orthopedic, and dental applications are some of the most common areas in which biomaterials are employed. 

Nitrogen was discovered in 1772, and it is such a versatile element that entire volumes have been devoted to its chemistry. It comprises 78% of the atmosphere, but it also occurs in many other naturally occurring materials including nitrates and amino acids. 

Naturally occurring chiral compounds provide an enormous range and diversity of possible starting materials. To be useful in asymmetric synthesis, they should be readily available in high enantiomeric purity. For many applications, the availability of both enantiomers is desirable. Many chiral molecules can be synthesized from natural carbohydrates or amino acids. The syntheses of (+)-exo-brevicomin (66) and negamycin (67) illustrate the application of such naturally occurring materials. 

Third, the modifications are being utilized by use as models for the modification of naturally occurring materials including renewable resource materials such as celluloses, polyamides and natural oils. 

Coplen, T.B., J.A. Hopple, J.K. Bohlke, H.S. Peiser, S.E. Rieder, H.R. Krouse, K.J.R. Rosman, T. Ding, R.D. Vocke, Jr., K.M. Revesz, A. Lamberty, P. Taylor, and P. DeBievre. 2001. Compilation of minimum and maximum isotope ratios of selected elements in naturally occurring materials and reagents. Water-Resources Investigations Report 01-4222, U.S. Geological Survey, 131 pp. 

Some methods measure more compounds than other methods because they employ more rigorous extraction techniques or more efficient solvents for the extraction procedure(s). Other methods are subject to interferences from naturally occurring materials such as animal and vegetable oils, peat moss, or humic material, which may result in artificially high reported concentrations of the total petroleum hydrocarbons. Some methods use cleanup steps to minimize the effect of nonpetroleum hydrocarbons, with variable success. Ultimately, many of the methods are limited by the extraction efficiency and the detection limits of the instrumentation used for measurement. 

Liquefied petroleum gas, natural gas, and refinery gas are mixtnres of products or naturally occurring materials and, fortunately, are relatively simple mixtures and do not suffer the complexities of the isomeric variations of the higher-molecular-weight hydrocarbons (Drews, 1998 Speight, 1999). 

---