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1. Anon. Heroin, J. Chem. Soc. London, 28: 315-318, 1875.

2. Anon. Heroin, Arch. Gesam. Physilogie, 72: 487, 1898.

3. Gates, M. and Tschudi, G., The synthesis of morphine, J. Am. Chem. Soc., 74: 1109-1110, 1952.

4. Elad, E. and Ginsburg, D., The synthesis of morphine, J. Am. Chem. Soc., 76: 312-313, 1954.

5. Rice, K.C., Synthetic opium alkaloids and derivatives. A short total synthesis of ( + -)-dihydrothebainone, (+- )-dihydrocodinone, and ( + -)-nordihydrocodinone as an approach to the practical synthesis of morphine, codeine, and congeners, J. Org. Chem., 45: 3135-3137, 1980.

6. Rapoport, H. and Bonner, R.M., Delta-7-desoxymorphine, J. Am. Chem. Soc., 73:5485, 1951.

1.4.2 cocaine

The social implications of cocaine abuse in the U.S. have been the subject of extensive media coverage during much of the 1980s and most of the 1990s. As a result, the general public has acquired some of the terminology associated with the cocaine usage. "Smoking crack" and "snorting coke" are terms that have become well understood in the American culture from elementary school through adulthood. However, there are facts associated with this drug which are not well understood by the general public. There are documented historical aspects associated with coca and cocaine abuse which go back 500 years. Recognizing some of these historical aspects enables the public to place today's problem in perspective. Cocaine addiction has been with society for well over 100 years.

Truxinic Acid Isomers
Figure 1.4.2.1

There are four areas of interest this section will address: (1) Where does cocaine come from? (2) How is cocaine isolated from the coca plant? (3) What does one take into the body from cocaine purchased on the street? (4) How does the chemist analyzing the drug identify and distinguish between the different forms of cocaine?

Cocaine is a Schedule II controlled substance. The wording in Title 21, Part 1308.12(b)(4) of the Code of Federal Regulations states:

Coca leaves (9040) and any salt, compound, derivative or preparation of coca leaves (including cocaine (9041) and ecgonine (9180) and their salts, isomers, derivatives and salts of isomers and derivatives), and any salt, compound, derivative, or preparation thereof which is chemically equivalent or identical with any of these substances, except that the substances shall not include decocanized coca leaves, or extractions of coca leaves, do not contain cocaine or ecgonine.

It is significant that the term "coca leaves" is the focal point of that part of the regulation controlling cocaine. The significance of this fact will become more apparent as this discussion progresses.

1.4.2.1 Sources of Cocaine

Cocaine is just one of the alkaloidal substances present in the coca leaf. Other molecules, some of them psychoactive (norcocaine being the most preominent) are shown in Figure 1.4.2.1 Cocaine is extracted from the leaves of the coca plant. The primary of source of cocaine imported into the U.S. is South America, but the coca plant also grows in the Far East in Ceylon, Java, and India. The plant is cultivated in South America on the eastern slopes of the Andes in Peru, and Bolivia. There are four varieties of coca plants — Erythroxylon coca var. coca (ECVC), Erythroxylon coca var. ipadu, Erythroxylum novogranatense var. novogranatense, and

Erythroxylum novogranatense var. truxillensey3 ECVC is the variety that has been used for the manufacture of illicit cocaine. While cultivated in many countries of South America, Peru and Bolivia are the world's leading producers of the coca plant. Cocaine is present in the coca leaves from these countries at dry weight concentrations of from 0.1 to 1%. The average concentration of cocaine in the leaf is 0.7%. The coca shrub has a life expectancy of 50 years and can be harvested three or four times a year.

The method of isolating cocaine from the coca leaf does not require a high degree of technical expertise or experience. It requires no formal education or expensive scientific equipment or chemicals. In most instances the methodology is passed from one generation to the next.

1.4.2.2 Historical Considerations

Prior to the 1880s, the physiological properties of cocaine and the coca leaf were not readily distinguishable in the literature. During that year, H.H. Rusby and W.G. Mortimer made the distinction between the physiological properties of "isolated" cocaine and the coca leaf. Mortimer wrote,

...the properties of cocaine, remarkable as they are, lie in an altogether different direction from those of coca.1

In 1884, two significant papers appeared in the literature. Sigmund Freud published the first of his five papers on the medicinal properties of cocaine.2 A few months later, Karl Koller discovered the use of cocaine as local anesthetic.2A In 1886, Sir Arthur Conan Doyle, an eye specialist who had studied at Vienna General Hospital, where Freud and Koller made their discoveries, made reference to Sherlock Holmes' use of cocaine in The Sign of Four.3 During the same year in Atlanta, Georgia, John Pemberton introduced to this country, caught up in the frenzy of alcohol prohibition, a beverage consisting of coca leaf extracts, African kola nuts, and a sweet carbonated syrup. The product was named "Coca-Cola"4 Pemberton received his inspiration from Angelo Mariani, a Corsican pharmacist working in Paris, who had been selling a coca leaf-Bordeaux wine tincture since the early 1860s. Mariani's product was the most popular tonic of its time, and was used by celebrities, poets, popes, and presidents.5 Patterns of coca consumption changed dramatically as society entered the 20th century. In the 19th century, cocaine was only available in the form of a botanical product or a botanical product in solution. When chemical houses, such as Merck, began to produce significant quantites of refined cocaine, episodes of toxicity became much more frequent, the views of the medical profession changed, and physicians lost much of their enthusiasm for the drug.

Until 1923, the primary source of cocaine was from the coca leaf. In that year, Richard Willstatter was able to synthesize a mixture of d-cocaine, l-cocaine, d-pseudococaine, and l-pseudococaine. This multi-step synthesis requires a high degree of technical expertise in organic chemistry and results in low yields.6 These financial and technical factors make the extraction of cocaine from the coca leaf the method by which most, if not all, of the cocaine is isolated for distribution on both the licit and illicit markets.

1.4.2.3 Isolation and Purification

The extraction and isolation of cocaine from the coca leaf is not difficult. There is more than one way to do it. South American producers improvise depending on the availability of chemicals. All of the known production techniques involve three primary steps: (1) extraction of crude coca paste from the coca leaf; (2) purification of coca paste to cocaine base; and (3) conversion of cocaine base to cocaine hydrochloride. The paste and base laboratories in South America are deeply entrenched and widespread with thousands of operations, whereas the conversion laboratories are more sophisticated and centralized. They border on semi-industrial pilot-plant type laboratories involving a knowledge of chemistry and engineering.

The primary isolation method used until recently is a Solvent Extraction Technique. The essential methodology involves macerating a quantity of coca leaves with lime water, and then adding kerosene with stirring. After a while the kerosene is separated from the aqueous layer. A dilute sulfuric acid solution is added to the kerosene with stirring. This time the kerosene is separated from the aqueous layer and set aside. It is common to save the kerosene for another extraction of the leaves. The aqueous layer is retained and neutralized with limestone or some other alkaline substance. The material that precipitates after the addition of limestone is crude coca paste containing anywhere from 30 to 80% cocaine, with the remainder of the cocaine matrix composed primarily of other alkaloids, hydrolysis products, and basic inorganic salts used in the processing. This solid material is isolated by filtration for purification of the cocaine.

The coca paste is then dissolved in dilute sulfuric acid, and dilute potassium permanganate solution is added to oxidize the impurities. This solution is then filtered, and ammonium hydroxide is added to the filtrate to precipitate cocaine base. This "cocaine" is not ready for shipment to the U.S. The cocaine will first be converted to hydrochloride for easier packaging, handling, and shipment.

A second method of isolating cocaine from the leaf which is more predominant today is the Acid Extraction Technique. In this method, the cocaine leaves are placed directly in the maceration pit with enough sulfuric acid to cover the leaves. The pit is a hole dug into the ground and lined with heavy duty plastic. The leaves are macerated by workers who stomp in the sulfuric acid/coca leaf pit. This stomping leaches the cocaine base from the leaf and forms an aqueous solution of cocaine sulfate. This stomping can continue for a matter of hours to ensure maximum recovery of the cocaine.

After stomping is complete, the coca solution is poured through a course filter to remove the insolubles including the plant material. More sulfuric acid is added to the leaves and a second or even third extraction of the remaining cocaine will take place. Maximized recovery of cocaine is important to the laboratory operators. After the extractions and filterings are completed, an excess basic lime or carbonate solution is added to the acidic solution with stirring and neutralizing the excess acid and cocaine sulfate. A very crude coca paste forms. The addition of the base is monitored until the solution is basic to an ethanolic solution of phenolphthalein. The coca paste is then back-extracted with a small volume of kerosene. The solution sets until a separation of the layers occurs. The kerosene is then back-extracted this time with a dilute solution of sulfuric acid. Then, an inorganic base is added to precipitate the coca paste. This coca paste is essentially the same as that generated by the solvent extraction method. The advantage to this Acid Extraction Technique is that a minimal volume of organic solvent is required. And while it is more labor intensive, the cost of labor in Bolivia, the major producing country of coca paste, is very low when compared to the financial return.

The resultant cocaine base, produced by either technique, is dissolved in acetone, ether, or a mixture of both. A dilute solution of hydrochloric acid in acetone is then prepared. The two solutions are mixed and a precipitate of cocaine hydrochloride forms almost immediately and is allowed to settle to the bottom of the reaction vessel (usually an inexpensive bucket). The slurry will then be poured through clean bed sheets filtering the cocaine hydrochloride from the solvent. The sheets are then wrung dry to eliminate excess acetone, and the high quality cocaine hydrochloride is dried in microwave ovens, under heat lamps, or in the sunlight. It is then a simple matter to package the cocaine hydrochloride for shipment. One of the more common packaging forms encountered in laboratories analyzing seizures of illicit cocaine is the "one kilo brick". This is a brick-shaped package of cocaine wrapped in tape or plastic, sometimes labeled with a logo, with the contents weighing near 1 kg. Once the cocaine hydrochloride arrives in the U.S., drug wholesalers may add mannitol or inositol as diluents, or procaine, benzocaine, lidocaine, or tetracaine as adulterants. This cocaine can then be sold on the underground market in the U.S. either in bulk or by repackaging into smaller containers.

1.4.2.4 Conversion to "Crack"

"Crack" is the term used on the street and even in some courtrooms to describe the form of cocaine base which has been converted from the cocaine hydrochloride and can be smoked in a pipe. This procedure of conversion from the acid to the base is usually carried out in the U.S. Cocaine base usually appears in the form of a rock-like material, and is sometimes sold in plastic packets, glass vials, or other suitable packaging. Cocaine hydrochloride is normally ingested by inhalation through a tube or straw, or by injection. Cocaine base is ingested by smoking in an improvised glass pipe. Ingestion in this manner results in the cocaine entering the blood stream through the lungs and rushes to the brain very quickly.

Cocaine hydrochloride is converted to cocaine base in one of two ways. The first method involves dissolving the cocaine hydrochloride in water and adding sodium bicarbonate or household ammonia. The water is then boiled for a short period until all of the precipitated cocaine base melts to an oil, and ice is added to the reaction vessel. This vessel will usually be a metal cooking pan or a deep glass bowl. As the water cools, chunks of cocaine base oil will solidify at the bottom of the cooking vessel. After all the cocaine base has formed, the water can be cooled and then poured off leaving the solid cocaine base which is easily removed from the collection vessel. The cocaine base can be cut with a knife or broken into "rocks" which can then be dried either under a heat lamp or in a microwave oven. It is not unusual when analyzing cocaine base produced from this method to identify sodium bicarbonate mixed with the rock-like material. This cocaine base sometimes has a high moisture content due to incomplete drying.

A second method of producing cocaine base from cocaine hydrochloride involves dissolving the salt (usually cocaine hydrochloride) in water. Sodium bicarbonate or household ammonia is added to the water and mixed well. Diethyl ether is then added to the solution and stirred. The mixture then separates into two layers with the ether layer on top of the aqueous layer. The ether is decanted leaving the water behind. The ether is then allowed to evaporate and high quality cocaine base remains. If any of the adulterants mentioned previously (excluding sugars, which are diluents) are mixed with the cocaine hydrochloride prior to conversion, then they will also be converted to the base and will be a part of the rock-like material that results from this process. The term "free base" is used to describe this form of cocaine. Cocaine base in this form is also smoked in a glass pipe. However, residual (and sometimes substantial) amounts of ether remaining in these samples from the extraction process make ignition in a glass pipe very dangerous.

1.4.2.5 Other Coca Alkaloids

In the process of examining cocaine samples in the laboratory, it is not uncommon to identify other alkaloids and manufacturing by-products with the cocaine. These other alkaloids are carried over from the coca leaf in the extraction of the cocaine. Many manufacturing by-products result from the hydrolysis of the parent alkaloids (benzoylecgonine from cocaine, or truxillic acid from truxilline). As a forensic chemist, it is important to recognize the sources of these alkaloids as one progresses through an analytical scheme.

The major alkaloidal "impurities" present in the coca leaf which are carried over in the cocaine extraction are the cis- and trans-cinnamoylcocaines and the truxillines. There are 11 isomeric truxillic and truxinic acids resulting from the hydrolysis of truxilline. Another naturally occurring minor alkaloid from the coca leaf is tropacocaine. The concentration of tropacocaine will rarely, if ever, exceed 1% of the cocaine concentration and is well below the concentrations of the cis- and trans-cinnamoylcocaines and the truxillines. Two other alkaloids from the coca leaf which have been identified are cuscohygrine and hygrine. These two products are not found in cocaine, just in the leaf.

The second class of substances found in the analysis of cocaine samples is the result of degradation or hydrolysis. Ecgonine, benzoylecgonine, and methylecgonine found in cocaine samples will be the result of the hydrolysis of cocaine. It is important to recognize that some of these manufacturing by-products, such as ecgonine, can be detected by gas chromatography only if they are derivatized prior to injection. Methyl ecgonidine is a by-product of the hydrolysis of cocaine and is often times identified in the laboratory by gas chromatography/ mass spectrometry. This artifact can also result from the thermal degradation of cocaine or the truxillines in the injection port of the GC. Benzoic acid is the other product identified when this decomposition occurs.

There are at least two substances that result directly from the permanganate oxidation of cocaine. N-formyl cocaine results from oxidation of the N-methyl group of cocaine to an N-formyl group. Norcocaine is a hydrolysis product resulting from a Schiffs base intermediate during the permanganate oxidation. There is also evidence that norcocaine can result from the N-demethylation of cocaine, a consequence of the peroxides in diethyl ether.

1.4.2.6 Cocaine Adulterants

The primary adulterants identified in cocaine samples are procaine and benzocaine. Lidocaine is also found with less regularity. These adulterants are found in both the cocaine base and cocaine hydrochloride submissions. The primary diluents are mannitol and inositol. Many other sugars have been found, but not nearly to the same extent. Cocaine hydrochloride concentrations will usually range from 20 to 99%. The moisture content of cocaine hydrochloride is usually minimal. Cocaine base concentrations will usually range from 30 to 99%. There will usually be some moisture in cocaine base ("crack") submissions from the water/sodium bicarbonate or water/ammonia methods. The concentration of cocaine base ("free base") from the ether/sodium bicarbonate or ether/ammonia methods will usually be higher and free of water.

The methods for identifying cocaine in the laboratory include but are not limited to: infrared spectrophotometry (IR), nuclear magnetic resonance spectroscopy (NMR), mass spectrometry (MS), and gas chromatography (GC). IR and NMR will enable the analyst to distinguish between cocaine hydrochloride and cocaine base. However, it is not possible to identify the form in which the cocaine is present utilizing this instrumentation.

conclusion

The user of either cocaine base or cocaine hydrochloride not only ingests the cocaine, but also other alkaloids from the coca plant, processing by-products, organic and inorganic reagents used in processing, diluents, and adulterants. There is no realistic way in which a cocaine user can ensure the quality of the cocaine purchases on the street, and "innocent" recreational drug use may provide more danger than the user would knowingly risk.

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