Starting reagents and materials
The process proceeds according to Scheme 1
Extraction of GBL
Hydrolysis of GBL
Hydrolysis of GBL proceeds according to Scheme 2
- 100 ml H2O
- 7.21 g THF
- 15.1 g KBrO3
- 13.6 g KHSO4
- 14 g Na2S2O5 dissolved in 150 ml H2O
- 150 ml H2O
- 250-300 ml DCM
- 50 g Na2SO4
- 3.38 g NaHCO3 dissolved in 15 ml H2O
- 3-neck flask 1000 ml
- Thermometer
- High efficiency double circuit reflux
- Magnetic stirrer
- Cold accumulators or ice
- Silicone grease like as MOLYKOTE High Vacuum Grease
- Glasses, allongs, funnels
- Separating funnel
- Distillation setup
- Watch glasses
- indicator paper
- Ethanol
- Silica gel
- Cobalt nitrate hexahydrate Co(NO3)2*6H2O
- FeCl3 ferric(III) chloride
Oxidation of THF
The process proceeds according to Scheme 1
The reactor must be hermetically sealed, connected to the atmosphere through a filter under the hood capable of absorbing bromine vapor! Fig 1
The reactor is placed in water, cooled by cold accumulators or ice. Fig 2
The addition of reagents to THF is carried out in the temperature range of 10-15℃. Then the temperature is increased to 20-25℃ for start the reaction.
7.21 g of THF and 100 ml of water placed in the reactor through a funnel. The temperature of the mixture in this stage should be below 20℃. Fig 3
7.21 g of THF and 100 ml of water placed in the reactor through a funnel. The temperature of the mixture in this stage should be below 20℃. Fig 3
Next, 15.1 g of KBrO3 and 13.6 g of KHSO4 are added to the resulting solution of THF in water. Fig 4
The mixture is stirred for 1-2 hours. Fig 5
Cooling stopped. At a temperature of 20℃, a yellow color appears and the reaction starts. Fig 6
After starting the reaction, the RM is kept for 20 hours at a temperature of 20-30℃. During this time, a significant amount of bromine vapor is formed. There is a risk of gas contamination in the room and bromine poisoning! The ventilation hood must work! Fig 7
RM after 20 h. Fig 8
Extraction of GBL
After 20 hours, bromine is neutralized with a solution of 14 g Na2S2O5 (sodium metabisulfite or pyrosulfite) and 150 ml of water. Fig 9
This solution is poured through a reflux into the reactor for neutralize bromine. Preparation of a solution of Na2S2O5 (sodium metabisulfite) is accompanied by the formation of sulfur dioxide SO2! Fig 10
After adding Na2S2O5 solution, 150 ml of water is added to absorb gases. Fig 11
The clear and colorless RM is transferred to a 2000 ml separatory funnel. Fig 12
Extracted with 250 ml DCM. Fig 13
The DCM layer is dried with anhydrous sodium sulfate until clear for 1-1.5 hours. Fig 14
DCM distilled off. When DCM is distilled, sulfur dioxide SO2 is formed! Fig 15
After distill stopped at a temperature of 90-110℃, the ball reflux is replaced on a direct cooler, and the fraction with a temperature of 200℃ is collected. Fig 16
GBL yield is 3.15 g (36,6%).
When the reaction is very active at T=60℃ and a big volume of bromine is formed, the yield of GBL is not more than 23%.Hydrolysis of GBL
Hydrolysis of GBL proceeds according to Scheme 2
A warm solution of sodium bicarbonate 3.38 g NaHCO3 in 15 ml of water is prepared. Fig 17
Distilled GBL is added to the prepared warm solution of NaHCO3 (not higher than 90℃). Fig 18
The solution is evaporated until crystallization and dried in a desiccator over alkali for 1-2 days. Fig 19
Dried salt. Fig 20
Yield 4.6 g
Qualitative determination of GHB salts
A) Reaction with 5% ferric chloride (FeCl3) solution. A few drops of ferric chloride solution are added to a few mg of dry matter or undiluted solution. In the presence of gamma-hydroxybutyric acid salts, the reagent turns red-brown. Fig 21
B) Reaction with 1% solution of cobalt nitrate in ethanol (88% ethanol + SiO2). The solution of hydroxybutyrate salt is evaporated to dryness at a temperature not exceeding 90℃. A few drops of cobalt nitrate reagent are added to a few mg of dry residue. In the presence of gamma-hydroxybutyric acid salts, the solution turns lilac. Fig 22
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