Amphetamine is a popular drug that is widely distributed around the world. Common production schemes are used to obtain amphetamine. Samples of "street" amphetamine have different qualitative composition and quantitative ratio of components. Experts analyzed known methods of amphetamine synthesis and found that both the main and intermediate stages produce by-products of the reactions. The analysis was carried out both empirically and by the results of specific chemical examinations, the objects of which were amphetamine. Also, poorly purified synthesis products, which are "street" preparations, contain trace amounts of used reagents and precursors, catalysts. Such substances can be called "markers", because they are a kind of markers, which guide the expert chemist to the specific method used to obtain the psychotropic substance. The types and quantitative content of "markers" contained in preparations depend largely on the method of synthesis, the ratio, source and purity of the initial reagents and precursors, the conditions of the reactions, as well as the method of purification, if it was carried out. Such a chemical investigation, aimed at detecting "markers" in the composition of preparations, can be carried out by various methods of physical and chemical analysis available to the expert.
Considering the ways of synthesizing amphetamine, it should be noted that the main precursors for its production can be: phenylacetone (1-phenyl-2-propanone), norephedrine, benzaldehyde, and benzyl cyanide. Let us consider the basic synthesis schemes from these possible precursors.
The synthesis of amphetamine from 1-phenyl-2-propanone (phenylacetone) can in principle be performed in two ways: by the Leikart reaction with the formation of N-formylamphetamine and 4-methyl-5-phenylpyrimidine as "markers", and by reductive amination (catalytic reduction on a metal catalyst) by five mechanisms:
- by reduction with Renay nickel to form bi-(1-phenylpropyl-2)-amine as a "marker;
- by reduction with an alkaline Urushibar catalyst in an autoclave. Characteristic "markers" in this case are Schiff bases formed by condensation of phenylacetone with amphetamine, inorganic impurities due to the use of a particular catalyst. It is also possible to establish signs of "nitropropene" and "oxime" schemes, so named by the characteristic intermediate products - "markers" (phenylnitropropene and 1-phenyl-2-propanone oxime);
- by reduction with aluminum amalgam with "markers" in the form of unreacted phenylacetone (larger in quantitative estimation than when obtained by other mechanisms). Traces of aluminum, chloride ions and mercury ions were also found in the reaction products;
- reduction with sodium cyanoborohydride, with traces of methanol and acetate ions detected as "markers" as well as the reagent itself;
- reduction with lithium alumohydride, the unreacted traces of which in the reaction products can be "markers. Traces of hydroxylamine and 1-phenyl-2-propanone oxime and acetate ions can also be detected in the "street" amphetamine synthesized according to this scheme.
The syntheses of amphetamine from benzaldehyde are based on the Henri reaction, an aldol-type reaction between an aldehyde and a nitroalkane, so the main "markers" in them are reduction products (beta hydroxynitro compounds) and nitroalkenes as side products (especially when aromatic aldehydes are used). Reactions can proceed by four main mechanisms:
- Lithium alumohydride reduction. "Markers" are traces of 2- nitro-1-phenylpropene, nitroethane, pentylamine, diethyl ether, and isopropanol, and the presence of sulfate and tartrate ions. It is important to note that by this synthesis the main product is formed as hydrochloride;
- reduction with Reney's nickel. "Markers" are traces of benzalgide, nitroethane, butylamine, 2-nitro-1-phenylpropene, and increased nickel content;
- recovery with sodium amalgam. "Markers" - traces of benzalhyde, nitroethane, butylamine, 2-nitro-1-phenylpropene, elevated sodium content in the final product;
- reduction in the electrochemical cell, with traces of benzalhyde, pentylamine, nitroethane, 2-nitro-1-phenylpropene, 1-phenyl-2-nitropropene, dimethyl ketone, the presence of acetate, phosphate and sulfate ions as "markers" can be detected. The final product is amphetamine phosphate.
The synthesis of amphetamine from norephedrine proceeds by three mechanisms:
- By reaction with hydrogen iodide acid and red phosphorus, with iodide ions and traces of phosphorus being the "markers". The crystallization stage of amphetamine hydrochloride is characterized by traces of acetone and chloride ions;
- according to the one-step Burch reduction reaction with an exothermic explosive reaction, in spite of this factor the final product is quite pure. Such "markers" as traces of ephedrine (pseudoephedrine), sodium (lithium) can be found in the products;
- by the reaction of thionyl chloride and norephedrine, trace amounts of which may be "markers", as well as traces of isopropyl ether, 2-amino-1-chloro-1-phenylpropane, and palladium.
"Markers" of the synthesis of amphetamine from benzylcyanide are: trace amounts of substances involved in the reactions and solvents benzylcyanide, magnesium, tetrahydrofuran, dichloromethane, the presence of sulfate ions.
It should be noted that the success of detecting "markers" in "street" amphetamine depends on many factors, among which the most important are: the degree of purity of the reagents used in the synthesis, the equipment of the laboratory and the experience of the chemist who produced the psychotropic substance.
Thus, using the analytical data we obtained on characteristic "markers" as part of a chemical examination, it becomes possible to establish a specific methodology for the synthesis of "street" amphetamine.
Considering the ways of synthesizing amphetamine, it should be noted that the main precursors for its production can be: phenylacetone (1-phenyl-2-propanone), norephedrine, benzaldehyde, and benzyl cyanide. Let us consider the basic synthesis schemes from these possible precursors.
The synthesis of amphetamine from 1-phenyl-2-propanone (phenylacetone) can in principle be performed in two ways: by the Leikart reaction with the formation of N-formylamphetamine and 4-methyl-5-phenylpyrimidine as "markers", and by reductive amination (catalytic reduction on a metal catalyst) by five mechanisms:
- by reduction with Renay nickel to form bi-(1-phenylpropyl-2)-amine as a "marker;
- by reduction with an alkaline Urushibar catalyst in an autoclave. Characteristic "markers" in this case are Schiff bases formed by condensation of phenylacetone with amphetamine, inorganic impurities due to the use of a particular catalyst. It is also possible to establish signs of "nitropropene" and "oxime" schemes, so named by the characteristic intermediate products - "markers" (phenylnitropropene and 1-phenyl-2-propanone oxime);
- by reduction with aluminum amalgam with "markers" in the form of unreacted phenylacetone (larger in quantitative estimation than when obtained by other mechanisms). Traces of aluminum, chloride ions and mercury ions were also found in the reaction products;
- reduction with sodium cyanoborohydride, with traces of methanol and acetate ions detected as "markers" as well as the reagent itself;
- reduction with lithium alumohydride, the unreacted traces of which in the reaction products can be "markers. Traces of hydroxylamine and 1-phenyl-2-propanone oxime and acetate ions can also be detected in the "street" amphetamine synthesized according to this scheme.
The syntheses of amphetamine from benzaldehyde are based on the Henri reaction, an aldol-type reaction between an aldehyde and a nitroalkane, so the main "markers" in them are reduction products (beta hydroxynitro compounds) and nitroalkenes as side products (especially when aromatic aldehydes are used). Reactions can proceed by four main mechanisms:
- Lithium alumohydride reduction. "Markers" are traces of 2- nitro-1-phenylpropene, nitroethane, pentylamine, diethyl ether, and isopropanol, and the presence of sulfate and tartrate ions. It is important to note that by this synthesis the main product is formed as hydrochloride;
- reduction with Reney's nickel. "Markers" are traces of benzalgide, nitroethane, butylamine, 2-nitro-1-phenylpropene, and increased nickel content;
- recovery with sodium amalgam. "Markers" - traces of benzalhyde, nitroethane, butylamine, 2-nitro-1-phenylpropene, elevated sodium content in the final product;
- reduction in the electrochemical cell, with traces of benzalhyde, pentylamine, nitroethane, 2-nitro-1-phenylpropene, 1-phenyl-2-nitropropene, dimethyl ketone, the presence of acetate, phosphate and sulfate ions as "markers" can be detected. The final product is amphetamine phosphate.
The synthesis of amphetamine from norephedrine proceeds by three mechanisms:
- By reaction with hydrogen iodide acid and red phosphorus, with iodide ions and traces of phosphorus being the "markers". The crystallization stage of amphetamine hydrochloride is characterized by traces of acetone and chloride ions;
- according to the one-step Burch reduction reaction with an exothermic explosive reaction, in spite of this factor the final product is quite pure. Such "markers" as traces of ephedrine (pseudoephedrine), sodium (lithium) can be found in the products;
- by the reaction of thionyl chloride and norephedrine, trace amounts of which may be "markers", as well as traces of isopropyl ether, 2-amino-1-chloro-1-phenylpropane, and palladium.
"Markers" of the synthesis of amphetamine from benzylcyanide are: trace amounts of substances involved in the reactions and solvents benzylcyanide, magnesium, tetrahydrofuran, dichloromethane, the presence of sulfate ions.
It should be noted that the success of detecting "markers" in "street" amphetamine depends on many factors, among which the most important are: the degree of purity of the reagents used in the synthesis, the equipment of the laboratory and the experience of the chemist who produced the psychotropic substance.
Thus, using the analytical data we obtained on characteristic "markers" as part of a chemical examination, it becomes possible to establish a specific methodology for the synthesis of "street" amphetamine.
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