Storing - hygroscopic properties of GHB

[porchy]

SWIM was speaking to a friend and they apparently said that GHB, if left out as a power form would turn into a liquid. Would SWIM be right in thinking that this substance absorbs enough moisture to become a solution again?

[MrG]

It becomes a thick goo more than a liquid.

[malsat]

Unless you've got the calcium or magnesium salts, which are non-hygroscopic.

[MrG]

I wonder what the TEK is for those salts. I don't imagine it is as easy as NaGHB.

[Pondlife]

From the Rhodium archives:

Calcium GHB

74 g analytically pure calcium hydroxide are suspended in 200 ml of tap water. 160 ml 4-butyrolactone are added in portions (each portion about 5 to 10 ml) and under stirring to this suspension at room temperature. After addition of 20 ml the reaction mixture warms to about 50° to 60°C. The addition of 4-butyrolactone is controlled such that the temperature remains between about 50° and 60°C, which takes about 1 hour. During this time the calcium hydroxide has dissolved practically completely. The reaction material is contaminated with a slight rust-yellow precipitate. It is thinned down with 300 ml methanol, is left for four hours to itself and is then filtered through a folded filter. The clear filtrate is cautiously treated with 200 ml acetone in the way that after each portion of acetone causing a precipitate time is allowed for the precipitate to redissolve. A waterclear solution is obtained which is placed for crystallization. After two hours of standing colorless crystals start to deposit. In this state the crystallization is accelerated by continuous addition of acetone (in total 100 ml). The crystallization time is 24 hours. The crystals are sucked off and are washed initially with 50 ml methanol and then additionally with 60 ml acetone. The crystals are dried at temperatures from about 60° to 80°C. in a drying cabinet. Yield: 230 g. Melting point 166-168°C. (immediately). The product is the waterfree nonhygroscopic calcium salt of the 4-hydroxybutyric acid. It is dissolvable as desired in water, the aqueous solution has a pH- value of 7 to 7.5. The salt can be stored as long as desired and does not change in air. Even upon storage no water is attracted from the air.

The residue crystallizes to a mass of colorless crystals, which is after dried at temperatures from about 60° to 80°C. Yield: about 105 g. Melting point 164-166°C. The product is Di-(4-hydroxybutyric) calcium. It is recrystallized by dissolving in little methanol followed by adding of acetone to cloudiness, and crystallizing in the cold.

Instead of methanol also ethanol and isopropanol can be employed for recrystallization with the same success. Without employing water containing alcohols as recrystallization medium or as additive of the recrystallization and purification no stable and in particular no nonhygroscopic calcium salts are obtained. The water content of the alcohols should be from about 3-10% by volume. The such obtained final product does easily dissolve in water, is not hydroscopic and has a pleasant aromatic odor.

Magnesium GHB

60 g magnesium hydroxide (analytical grade) are suspended in 200 ml tap water under stirring. In a stream and under stirring 160 ml butyrolactone are mixed into this suspension. Then the mixture is heated on a water bath for 6 hours under stirring in a 2-liter-flask. The magnesium hydroxide dissolves practically completely. The flask is allowed to stand overnight, while contaminants deposit and the solution is decanted without effort from the contaminant deposit. The water clear decantate is initially stirred with 100 ml acetone for 10 minutes. The colorless sirupy liquid, which now turned more viscous, is mixed again with 100 ml acetone as described above, the acetone is again removed by decanting and the fairly viscous, colorless sirup is left to itself at room temperature for about 2 to 4 hours. It solidifies to a colorless crystal mass, which is comminuted in a mortar and dried for several hours in air. Melting point 76°C to 78°C. Yield: 314 g in analytically pure form.

This magnesium salt contains about 5 mole of water of hydration. It is not hydroscopic, is stable and can be stored for arbitrary long times. By drying over several hours at 40° to 50°C it loses part of its water (1 mole) of crystallization and then melts at 118° to 120°C. Waterfree magnesium 4-hydroxybutyrate can be produced by removal of water by sublimation and/or evaporation of water under decreased partial pressure of water and at elevated temperature or by crystallization from a solution containing an organic solvent. The waterfree salt melts at 172-174°C. The chemical analysis shows 10.50 weight percent magnesium (calculated 10.55 weight percent magnesium). All modifications are nonhygroscopic and stable during storage. 1g of the magnesium salt dissolves in 2 ml water at room temperature, the pH of the aqueous solution is 7.

It dissolves easily in water, methanol and ethanol, it does not dissolve in ether and hydrocarbons, it is not hygroscopic, is storable and has a pleasant aromatic odor.

In essence, it appears that in both cases, GBL will react with Ca or Mg hydroxide with mild heat to form Ca/Mg GHB. The process appears to take longer than for Na or K GHB though.

[trptamene]

And much more on GHB chemistry found in the rhodium archive as well.
http://www.drugs-forum.com/chemistry...try/index.html