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Chemical difference between ketamine crystal and its freebase?

M

madcow2

Greenlighter
Joined
Nov 17, 2009
Messages
13
1) Knowing Ketamine HCL salt is very soluable in water.

2) Pure Ketamine crystal ( not HCl form) should also be soluble in water.

Questions:
BUT why the Freebase ( after basified from its salt form) Ketamine is INSOLUBLE in water and participate out during acid / base extract for purification?

Some quote when basified ketamine HCL , its freebase participate color changes with degree of high PH value, is that so? Will its HCL salt participate out when PH is 7 neutral?

Is there chemical structural difference between ketamine crystal and freebase?

Can someone smoke Ketamine freebase ?

Sorry for my native chemical knowledge and questions.
 
madcow2 said:
1) Knowing Ketamine HCL salt is very soluable in water.

2) Pure Ketamine crystal ( not HCl form) should also be soluble in water.

Questions:
BUT why the Freebase ( after basified from its salt form) Ketamine is INSOLUBLE in water and participate out during acid / base extract for purification?

Some quote when basified ketamine HCL , its freebase participate color changes with degree of high PH value, is that so? Will its HCL salt participate out when PH is 7 neutral?

Is there chemical structural difference between ketamine crystal and freebase?
Click to expand...

Freebase amines are not usually soluble in water, you would need something like diethyl ether to dissolve them.

The HCl salt won't precipitate out in water because its soluble in water, although basifying should cause the unprotonated form of ketamine to precipitate out especially if you cool the mixture in an ice bath.
 
1) will ketamine amines participate out if ph neutral?
2) Freebase amines not soluble in water, but why ketamine crystal, ( not HCL salt) can be dissolved? Solution formed by dissolved Ketamine crystal ( not HCl salt) , ph should also be alkai, in therory, right?
Instead of diethyl ether, which is difficult to handle, wonder using pentane , or hexane as alternative solvent will dissolved the amine freebase?
 
Freebases are generally insoluble, while salts are soluble because when you form the salt you change from

drug-NH2 (somewhat non-polar)

drug-NH3+ Cl- (doesnt get much more polar than an ionic compound)

As we remember from chemistry classes, polar compounds dissolve in polar solvents. Water is a polar solvent. Hence, salts of amines dissolve in water, the bases dissolve in non-polar solvents (generally speaking)

Different compounds will change between freebase and salt at different pH - Same principles described in http://en.wikipedia.org/wiki/Acid_dissociation_constant
apply, though that article is more focused on organic acids (the opposite situation, with a non-ionic species losing a proton and acquiring a negative charge)

Note that in the case of alkaloids, because one of the forms is usually insoluble or only slightly soluble in the solvent being used, the concentration of that species stays near zero, driving the reaction to completion when the pH reaches that critical value. As i said earlier, this pH varies widely. You can't convert 2C-I to the free base with carbonates (not strong enough base), while that works with other amines.

So.... whether ketamine will precipitate out of a neutral solution, you'll have to dig through references to figure that out - but be aware that if you dissolve the salt in water, it will not be neutral, it will be acidic.
 
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Sorry, still dont understand why pure ketamine crystal ( not Ketamine HCl crystal) , can still dissolve in water? is ketemine crystal ( not it HCL salt) alkali ?

why would the Non-HCl salt is acidic in solution? Yes, agreed, ph of its HCL salt solution is acid , around 5.5.
But find no reference to ph value of its (non-HCl salt solution), that's why I GUESSED it should be alkaline.

A chemist friend told me that Ketamine ( not HCl salt) cannot be dissolved in Pentane, but can be dissolved in ether, that is why people use 50%Pentane/ 50% Diethyl Ether mixed for two solvent mixed recrystalization, is that true?
 
Ketamine crystal is Ketamine HCl. Freebase ketamine would likely be an oil.

The only freebase amines I know that occur in solid form are simple tryptamines (DMT for example).

I don't know where you would come across freebase ketamine unless you basified a ketamine solution yourself; Which I don't see the point of doing.

If you bought ketamine crystal; it's water soluble ketamine HCl.
 
Ketamine crystal is still Ketamine HCl

There's some confusion, i think, because the HCl is a salt of ketamine, but ketamine on the black market is also frequently contaminated with table salt from the saline injectable solution that ketamine is frequently supplied in. So there's confusion between "the salt of ketamine" and "ketamine and salt"

Plenty of freebases of amines are solid. Usually waxy solids, rather than crystaline ones. Crack cocaine, for example
 
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TheAzo said:
Plenty of freebases of amines are solid. Usually waxy solids, rather than crystaline ones. Crack cocaine, for example
Click to expand...

Yeah, I suppose that's true. A freebase will be a solid at room temperature if the melting point is above room temperature. It's like any other oil; many oils will turn to a waxlike solid if put in the freezer. Butter turns to liquid if heated only slightly.

The thing is freebase solids are usually not crystalline though; they're like a frozen oil; a wax.

I also totally forgot about crack.
 
Ah! Now I understand. Ketamine has two forms only. Crystals are all Hcl salts... and Freebase in Wax..solid form in room temperature. Thanks for clearing up my confusion.

Can freebase be dissolved in pentane instead of diethyl ether ? Would like to purify the freebase before crystallization using pentane alone or mixed with other solvent but not ether.

Instead of the " 50%pentane and 50% diethyl ether " suggested by many googled sites. Dont want to handle ether. Thanks.
 
Sorry , I am confused again, after reading your "advanced drug forum" about Ketamine salt solubility".

below are quote from the forum:

"The Merck 13th CD edition lists minimal solubility data:
Ketamine FB: Properties: Crystals from pentane-ether, mp 92-93°.
pKa 7.5. pH of 10% aq soln 3.5.
Ketamine HCl from the Merck: White crystals, mp 262-263°. Soly in water: 20 g/100 ml."

For my naive understanding,it meant Ketamine Freebase can be formed "crystals" from pentane-ether" which has mp 92-93 C unlike its HCL crystal mp at 262-263 C

How come the freebase can form crystal from pentane-ether (which are only solvents for purification, right?), if all you said that ketamine crystals are all HCL salt??

Thanks in advance for solving the "crystal" confusion.
 
Ketamine, like cocaine, can exist in two forms: a fat-soluble freebase form and a water-soluble hydrochloride salt. Both are solid products but they behave differently. Compare crack cocaine and powder cocaine, They can be converted between by adjusting the pH: acid environments favor formation of water-soulbe salts, basic environments form freebase.

Ketamine freebase is quite uncommon, 98 times out of 100 when someone says they have ketamine they are referring to the hydrochloride salt.

Recrysatllizing the freebase doesn't seem productive, you're gonna have to convert it to HCl salt to sniff or inject it...
 
I came across an aqueous ketamine base solution at a veterinary shop in Costa Rica 15 years ago or so. The bottle was larger and probably less concentrated than the little vials that you most often see from pharmaceutical companies, but I really don't recall the concentration. We bought one and evaporated the water. The free base is very much a white solid - but more chalky/less crystalline than the HCl salts we are used to seeing. I came across this thread looking for solubility information to help me separate a ketamine salt from an apparent inorganic salt adulterant. My memory of the base having some decent water solubility is troubling, but hopefully it will still greatly favor a solvent like xylene or dichloromethane...
 
P Schwangles said:
I came across an aqueous ketamine base solution at a veterinary shop in Costa Rica 15 years ago or so. The bottle was larger and probably less concentrated than the little vials that you most often see from pharmaceutical companies, but I really don't recall the concentration. We bought one and evaporated the water. The free base is very much a white solid - but more chalky/less crystalline than the HCl salts we are used to seeing. I came across this thread looking for solubility information to help me separate a ketamine salt from an apparent inorganic salt adulterant. My memory of the base having some decent water solubility is troubling, but hopefully it will still greatly favor a solvent like xylene or dichloromethane...
Click to expand...
Are you sure it was freebase?
Ive Never heard anyone having or even mentioning freebase ket, dont see any reason for it to be available either.

What would be the benefit of converting ket HCl to freebase?
 
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