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Conversion of APAAN (a-phenylacetoacetonitrile) into BMK (benzylmethylketone) (Large scale)

William Dampier

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APAAN is frequently used for BMK production because:
• The price of APAAN is relatively low as compared to the price of BMK;
• APAAN to BMK conversion requires no specific chemical knowledge;
• APAAN to BMK conversion does not require complex or expensive
production; and
• A high yield (between 60% and 75%) is easily achieved.

The APAAN is subsequently taken to a location where it can be converted into BMK. This illegal conversion is relatively simple and does not require expensive production equipment or extensive chemical knowledge. The APAAN can be converted with the aid of a strong acid, such as phosphoric acid, sulphuric acid or hydrochloric acid, and in some cases heating of the reaction mixture. The conversion results in BMK, an ammonium salt, and CO2. (plus some remaining acid and water).
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As the conversion process does not take place in an ideal production environment, or under the best of circumstances, the post-production residue will contain a mixture of BMK, acid, water, ammonium salt, and sometimes APAAN, depending on the substance ratios. In addition, the mixture will contain a number of by-products, generated by the BMK and the acidic conditions.

In a number of investigations it emerged that illegal producers use an excess of acids to ensure full conversion of the APAAN. If water is added to the process or if the acid contains water, the reaction mixture will contain water at the end of the conversion process. The water content will be small in case of phosphoric acid. Two layers of fluid will develop: BMK on top of an acidic watery fluid.

The conversion of APAAN to BMK takes place in a number of stages, namely:
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APAAN to BMK conversion requires a hydrolysis reaction. This is a reaction with water that can be carried out using an acid (hydrochloric acid, sulphuric acid or phosphoric acid) or a strong base, such as caustic soda (sodium hydroxide).

The reaction takes place in a number of stages. In hydrochloric acid, for example, the CN group is first converted into an acid group, COOH, simultaneously forming ammonium chloride. Chemically speaking, ammonium chloride is NH4CL, which contains the N atom of the CN group. If sulphuric acid is used in the reaction, ammonium sulphate will be formed in this stage.


In the following reaction stage, decarboxylation takes place. This means that CO2 is formed out of the acid group. After this, the reaction is finished and the APAAN to BMK conversion complete. Under normal conditions, no HCN – the extremely poisonous hydrocyanic acid – is formed during the reaction. It is unknown what
4 happens if the same reaction takes place at very high temperatures. In the known production processes, this can only happen if no water remains in the reaction system, as water ensures that the mixture’s boiling point is 100°C. At 100°C, APAAN is in liquid form, which facilitates the blending process.


APAAN conversion using phosphoric acid.

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Description of the chemical process:
In stage 1, APAAN is mixed with phosphoric acid. The mixture must then be heated to a temperature of 150 °C up to 160 °C to allow for proper conversion. This is a much higher temperature, then when sulphuric acid or hydrochloric acid are used. No water is added to the reaction mixture; this would prevent the mixture from reaching the high temperature required, as water evaporates at temperatures > 100 °C.

The mixture is heated for several hours, during which the oily crude BMK is separated from the acidic bottom layer. The bottom layer consists of acid with some dissolved BMK, ammonium phosphate and, potentially, some unconverted APAAN.

Description of the technical process:

Given that the temperature of the reaction mixture must be 150 °C up to 160 °C, if phosphoric acid is used, an external heating source is required. There are several options, such as electric heating mantles and gas burners, which have the disadvantage that exact temperature control is impossible, or electric heating in combination with thermal oil.
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Glass vessels, such as round bottom flasks or reaction flasks, can be used as reaction vessels. Metal reaction vessels with a protective coating, such as enamel or Teflon on the inside, can also be used. The coating ensures that the strong acids do not corrode the metal.
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APAAN conversion using sulphuric acid.

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Two production methods were found for conversion with the aid of sulphuric acid:
a. Use of an external heating source;
b. Heating resulting from an exothermic reaction between the sulphuric acid and water.

Use of an external heating source.

This conversion method requires a source of heat. In the first APAAN conversion labs that were discovered, 22-litre preserving kettles were frequently used. An advantage of these kettles is that they are easily modified. It is simple to make holes to install exhaust pipes for fumes and gases, and a stirring mechanism.

Description of the chemical process:

Stage 1: the APAAN is mixed with water and concentrated sulphuric acid. The sulphuric acid may also be slightly diluted beforehand. As the mixing process generates a lot of heat, the mixture must be cooled. The reaction mixture can be cooled to 100° C, which makes it possible to immediately proceed to stage 2.

Stage 2: the mixture is kept at a temperature of 100 °C for a little while, and subsequently cooled to below room temperature.

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Stage 3: a large quantity of water is added to the mixture, after it has been cooled to the right temperature.

Stage 4: the reaction mixture is reheated to 100 °C and kept at this temperature for several hours, during which time the oily crude BMK separates from the acidic bottom layer. The bottom layer consists of diluted sulphuric acid, with some dissolved BMK, ammonium sulphate, possibly some unconverted APAAN and a few by-products.

When preserving kettles were used in one of the first APAAN conversion labs, the mixing ratio was 2.2 kg of APAAN to 4 litres of concentrated sulphuric acid and 12 litres of water.

Description of the technical process:

During the first production stage, the APAAN is mixed with concentrated sulphuric acid. The heat, generated in the process, must be reduced by cooling the mixture. When preserving kettles were used, a cooling system, consisting of a mortar tub with a drainage pipe in the base, was installed. The preserving kettle was placed on three bricks on the bottom of the tub. The bricks prevented the preserving kettle from touching the wet base of the tub and the electric heating element from continued exposure to water.

A ring of plastic tubing, equipped with thin nozzles on the inside, had been installed on top of the mortar tub. This tubing had been attached to the water pipes, so that the nozzles sprayed cold water against the outside of the preserving kettle. This allowed for the controlled reduction of the reaction mixture’s temperature. We will see a similar cooling system – a ring of tubing around the reaction vessel – in the description of other conversion methods.
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On top of the preserving kettles is a 24 Volt electromotor that powers a stirring mechanism, which mixes the APAAN with the acid, optimizing the reaction.

After completion of the second stage, the mixture is transferred to a second set of processing equipment. In this case, preserving kettles without a cooling system have been used. Water is added after the mixture has been transferred. The mixture is then heated to a temperature of 95 to 100° C. Because of their limited production capacity – about 1.5 to 2 litres of BMK per production batch – several preserving kettles are used simultaneously. These are all attached to an exhaust system that removes the poisonous or harmful fumes and gases.

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Heating by means of the exothermic reaction between sulphuric acid and water.

This conversion method does not use an external heating source, but reaction heat generated by mixing sulphuric acid with water. The rate, at which the water is added, determines the amount of heat generated.

Description of the chemical process:

Stage 1: the APAAN is mixed with water and concentrated sulphuric acid. As this generates a great deal of heat, the mixture must be cooled.

Stage 2: after cooling, a large quantity of water is added to the mixture. This should be done in a controlled manner. Mixing water and sulphuric acid generates a great deal of heat, which should be limited by adding the water little by little over several hours. The temperature should not rise too much. In the process, the oily crude BMK is separated from the acidic bottom layer. The bottom layer consists of diluted sulphuric acid, a little BMK, ammonium sulphate, and possibly some unconverted APAAN and a few by-products.

Description of the technical process:

In principle, this conversion method is similar to the method that uses an external heat source. The first laboratory where this method was used was found in February 2011. In this lab, a plastic reaction vessel was used, with a content of 750 litres.

As was the case with the preserving kettles, this reaction vessel was equipped with a cooling system on the outside, consisting of a ring of copper piping with nozzles. The outside of the metal grid had been sealed with foil that caught the cooling- water. To heat the reaction mixture, water was added using a fluids pump. During the conversion process, the temperature was monitored by an electronic thermometer.
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Subsequently, the content of the vessel was mixed using the stirring mechanism. The fumes and gases released in the process were cooled with the aid of a cooling system made from double-walled PVC tubes. This cooling system could be equipped with active carbon filters at the tail ends.

A large-scale conversion set-up like this was found only once. Usually, plastic barrels with band clamp lids are used, which are placed in a mortar tub. A similar cooling system is installed around the lids of these barrels. The mixture is stirred by an electrically powered stirring mechanism installed over the barrel. A disadvantage of this conversion set-up is that, unlike the preserving kettles and the plastic vessels mentioned above, this is an open process, which means that fumes and gases are released from the open-top of the barrel and will spread freely throughout the production space. Therefore, the air in the production space should be extracted by an exhaust system, possibly in combination with an active carbon filter.

The emission from the reaction vessel into the production space is a major disadvantage of this set-up. Illegal producers, as well as investigation and emergency services, will be exposed to these fumes and gases in the case of a calamity and/or investigation. In addition, the material in the production space will be contaminated and corroded by the acid and poisonous fumes and gases. Further, processing of the content of such large set-ups was shown to cause considerable pollution of the location.
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APAAN conversion using hydrochloric acid.

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Stage 1 – the conversion reaction

The APAAN is mixed with hydrochloric acid, at a ratio of 1 litre APAAN to 3 litres hydrochloric acid, 36%. This mixture must be stirred thoroughly, and heated to a temperature of 95 °C for a period of 10 hours, during which time the mixture must be stirred regularly. The fumes and gases generated during the process are removed through a gas scrubber, which neutralizes the fumes.

The heaters are turned off as soon as the conversion reaction is complete. The acidic, dark brown BMK will float on top of the fluid. It can be separated using a separatory funnel. If large quantities of APAAN have been converted into BMK, the BMK can be skimmed off using a metal ladle.

Description of the technical process:

APAAN to BMK conversion, using of hydrochloric acid, does not require any complex or expensive production equipment. Since hydrochloric acid has a corrosive effect on iron and stainless steel, plastic barrels are used for the conversion reaction. These may vary in size from 80 to 220 litres.

The mixing of the reaction mixture of APAAN and hydrochloric acid is not done with electric mixing equipment, as is the case for APAAN conversion with sulphuric acid, but is usually done by hand, using a wooden or plastic stick or spatula.

In most conversion labs that used hydrochloric acid, the set-up resembled the schematic representation below.

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The two outer barrels are used for the conversion of APAAN to BMK. Tubes protruding from the lids of these barrels lead into the central barrel, which contains a fluid – either a water and caustic soda solution or an alkaline soap – that neutralizes the fumes.

The central barrel may also contain an internal spraying mechanism: A submersible pump in the liquid and a ring of tubing with nozzles immediately under the lid create a mist of the liquid in the barrel. This is done to optimize neutralization and precipitation of the fumes.
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The fumes and smell released in filling, mixing and emptying the barrels is extracted by an extractor fan equipped on the front with an active carbon filter.
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As the reaction between the APAAN and the hydrochloric acid generates now or insufficient heat to complete the conversion to BMK, an external heating source is required. Heating mantles are frequently used for this purpose. In the industrial sector, these mantles are used to heat fluids with a melting point around room temperature for easier transport or processing.
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The heating mantle can be attached to the plastic barrel, simply using three adjustable straps, after which the desired temperature is set with the aid of a thermostat.

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Separation – stage 2.

After the APAAN is converted to BMK, the BMK can be separated off using a separatory funnel or a metal ladle. At that time, the BMK is still acidic and can be neutralized using a caustic soda (NaOH) solution, with a ratio of 25 kg caustic soda to 50 litres water.

This reaction will generate heat. In some conversion labs, the barrels used for this stage are cooled in metal cooling basins filled with a layer of cooling-water. In the labs in question, the reaction mixture was pumped into plastic barrels in the cooling basins after the first stage: the conversion stage.

After the BMK is neutralized, it can be separated with the aid of a separatory funnel or a metal ladle.

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Purification – stage 3.

After conversion and neutralization, the BMK is dark brown in, and can subsequently be purified or cleaned using steam distillation or another type of distillation. This distillation removes water and synthesis contaminations with boiling points that vary significantly from that of BMK. After distillation, the remaining BMK is pale yellow.

Comment:
The neutralization and purification stages are not essential. The acidic, dark brown coloured BMK can be used as it is for the production of amphetamine and methamphetamine. In some conversion labs, only the conversion process was found, other labs also showed evidence of the neutralization stage.

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KokosDreams

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What's the recommended route to go from BMK -> Amphetamine Freebase when the BMK was produced with APAAN + Hydrochloric Acid?

Also, what's the final yield of pure Amphetamine Freebase?
 
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