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Author: Subject: Gamma-butyrolactone from GABA
Tsjerk
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[*] posted on 22-7-2019 at 13:54


Am I missing posts?I didn't read anything anything about cyanides.

[Edited on 22-7-2019 by Tsjerk]
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[*] posted on 22-7-2019 at 22:05


Quote: Originally posted by draculic acid69  
Monochlorinate 1,3 propanediol to 3chloropropanol then react with nacn followed by hydrolysing the nitrile to GBL is another option correct?


Is this what you were looking for?
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[*] posted on 22-7-2019 at 22:40


How can they outlaw the production, that seems short sighted. I can see restricting sale as that would make sense, but there are MASSIVE sales of GBL and I'd venture a guess only a few % is diverted to illicit use as if the rest was used illicitly, the entire would would be passed out 24/7 365.

So, I'm guessing India is going to start production of this or maybe Thailand. There will be some country that will fill the gap as it is needed for industry. Maybe BASF will see a major jump in sales or maybe BASF was behind getting Bejeing to outlaw it.
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[*] posted on 22-7-2019 at 23:57


Quote: Originally posted by draculic acid69  
Anyway back to the chemistry, does anyone think the method I posted with cyanide and chloropropanol seem like it would be a good route to this compound. the grignard can't be used to make it so this seemed logical. 1,2,dichloroethane could be used for 1,4,BDO if formaldehyde can be piped in gaseous form.


Don't you think may be easier start from acrylic acid, doing an anti-markovnikov HBr addition with peroxide and later a hydrolysis to GHB with aqueous KOH?

Neither everybody can do purchase alkali cyanide and worse then work with this poison in a safety way.
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[*] posted on 23-7-2019 at 09:38


Quote: Originally posted by RogueRose  
How can they outlaw the production, that seems short sighted. I can see restricting sale as that would make sense, but there are MASSIVE sales of GBL and I'd venture a guess only a few % is diverted to illicit use as if the rest was used illicitly, the entire would would be passed out 24/7 365.

So, I'm guessing India is going to start production of this or maybe Thailand. There will be some country that will fill the gap as it is needed for industry. Maybe BASF will see a major jump in sales or maybe BASF was behind getting Bejeing to outlaw it.



Pardon me, they have indeed restricted its sale and specifically export to non-accredited buyers.
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[*] posted on 23-7-2019 at 09:41


Here's a more detailed rundown of the GABA2GBL synthesis for the home chemist for anyone who's interested.

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[*] posted on 25-7-2019 at 02:05


As far as acrylic acid isn't it a carbon too short?
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[*] posted on 25-7-2019 at 03:30


Quote: Originally posted by draculic acid69  
As far as acrylic acid isn't it a carbon too short?


Yes, you've got me. I was sleepy when I wrote this. The correct start point would be 3-butenoic acid aka vinylacetic acid.

But hey, isn't a good and easier synthesis instead using cyanide?
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[*] posted on 26-7-2019 at 01:21


Quote: Originally posted by Tsjerk  


Did you stirr the catalyst as a solid? I'm just making sure it was dry when you did the heating.

I remember some literature that adviced to do the heating by slowly going up to the 350. I might have found it in one of the articles Erowid.org cites. There was some data about how the catalyst forms, with graphs on endothermic and exothermic phases during the formation. I have the feeling the catalyst is more active if you give it time to go through all the steps.

I never noticed much smoke, only ammonia coming off.

Never trust what is written on erowid.org/the Hive, always try to find the articles were they got their information from, usually they just summarize and screw up things along the way.

[Edited on 21-7-2019 by Tsjerk]


I found a copy of the original published literature. I think I can help you with your less than stellar 20-30% catalyst yields. First, you blast small portions (say, 5-10mls?) with 350C heat without stirring. If you've done this right you should see a lot of fumes evolve. You collect each portion until you have the volume desired then heat from room temperature to 350C for 15 minutes while stirring. The lit says to use a stainless steel propellor scraping close to the surface of the flask but a wire propellor should move around your solids with greater efficiency, particularly if you're cooking more catalyst than the 4g described for the dehydrogenation of 1,4 BDO.

I believe that this is where my process was breaking down. I have scheduled time in the lab for this weekend so I'll let you know how I get on.
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[*] posted on 26-7-2019 at 01:36


The dehydrogenation is a one-way reaction, given enough time it will get to an end-point. I got 20-30% after a couple of hours at reflux with a crappy catalyst. I just didn't bother to continue and distilled of the left over 1,4-BDO. Taken in account the recycled reagent I probably got a 80-90% yield. I didn't bother to distill to dryness.

I think my method for preparing the catalyst is more fail-proof, you just have to be able to get your preparation to 350. Use a slowly increasing temperature so you don't get hot spots. When using small enough quantities there is no need for stirring.
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[*] posted on 3-8-2019 at 06:01


I've been interested in the synthesis by the home chemist of a related solvent: THF (tetrahydrofuran).
It can be made from 1,4-butanediol, same as GBL, and THF can be oxidized to GBL. I believe the industrial route for GBL proceeds via 1,4-butanediol, and so do some routes to THF.
I believe THF itself might be convertable back to 1,4-butanediol, undoing the cyclization, maybe with an acid catalyst in presence of water? I've seen some claims of people achieving this using HCl and another with H2SO4, but I never checked the references on this reaction,

As far as sources of THF go, I believe it might be found in some PVC glues, although I would be cautious about distilling it as it might not stabilized like the lab grade one and it can form explosive peroxides, some care might need to be taken if using that source.
My main interest in it is that it's a common lab solvent, used in various reductions (such as with sodium borohydride and LAH) and in grignard reactions (both need it to be anhydrous), sometimes diethyl ether is used, sometimes THF serves better (such as for solubility reasons).
Lab suppliers, some that sell to the public seem to stock it at prices ranging from 60EUR to 13EUR/l depending on the volume (13EUR/l for about 30l), while chinese bulk supplies will even sell it to you for less than 2$/l, if buying by the barrel.
While I do expect that most people that actually use it simply buy it as it's usually available and has wide utility, a pet pevee of mine is to try avoiding using chemicals that I'd have trouble synthethizing from scratch from materials that are available everywhere to the general public.
I don't believe THF itself is available to the general public everywhere, as the sciencemadness wiki gives one example where it is banned as it is a precursor to GHB, GBL, 1,4-BDO.

Given these facts and it's importance, I believe finding a way for the hobbyist to synthethize it no matter their location and commercial availibility is important.

For the longest time it seemed every route I could find to THF involved a hydrogenation along the way, especially the industrial routes:

1. acetylene + formaldehyde -> 1,4-butynediol. 1,4-butynediol. is hydrogenated over a catalyst (raney nickel? Pd/C?), usually at high pressures to 1,4-butanediol. The 1,4-butanediol dehydrates to THF with H3PO4 at high temperatures.
The conditions for some of theses steps are not mild at all, some proceed in gas phase, some require large pressures.

2. it's possible to make furan by decarbonylation of furfural, Pd catalyzed, and furfural itself may be obtained from pentoses such as xylose, extracted for example from waste corn cobs which might be attained fairly cheaply. Such a procedure is described on orgsyn.org.
Hydrogenation of furan to THF can proceed at milder conditions (5-10atms), I've read a paper on this before, written around the 50s, catalyst might have been Raney Nickel (I don't know if Urushibara Nickel works for this, it might), sciencemadness wiki states only 2-4atms are required, which is fairly mild. The procedure on orgsyn used Pd/C and higher pressures (around 6.8atms or 100psi), see: http://www.orgsyn.org/demo.aspx?prep=CV2P0566 (they also give an example using RaNi at 100-150atm, which obviously requires an autoclave or hydrogenator).
See also: http://www.orgsyn.org/demo.aspx?prep=cv1p0274 furan from 2-furancarboxylic acid. and 2-furancarboxylic acid from furfural ( http://www.orgsyn.org/demo.aspx?prep=CV1P0276 ) and furfural ( http://www.orgsyn.org/demo.aspx?prep=CV1P0280 ) from corn cobs. Wikipedia also claims that furan may also be obtained from pine wood: "It can also be prepared directly by thermal decomposition of pentose-containing materials, and cellulosic solids, especially pine wood. "

The disadvantage of this is that not every hobbyist might have a ball mill and the right inert atmosphere conditions to prepare the RaNi catalyst, and in the cases where higher temperatures are needed, they might not have the autoclave or hydrogenation apparatus needed, and making those is no quick weekend project either.
And if one had the hydrogenation catalyst, they might not even bother with making THF as it was possible that their use of THF was some reduction and RaNi or Pd/C might serve just as well depending on the reaction.
Of course one might ask if using reducing agents such as LAH or NaBH4, you'd buy them anyway, so why not buy the THF as well: LAH has been made by hobbyists before, see len1's book, and I do believe the borohydride can be synthethized as well with some effort, although it might not be the most trivial thing, but I won't go further into their synthesis as it'd be offtopic here.

3. There's some route from an ester of maleic anhydride that might be accessible, but it still involves a hydrogenation for the final step, thus the same issues as 1 and 2 apply. Some route from allyl alcohol followed by hydrogenation also exists, I never looked into it.

4. A route I've seen mentioned on https://www.sciencemadness.org/smwiki/index.php/Tetrahydrofuran from n-butanol with the use of soluble lead acetate salts, this seems quite accessible, but using soluble lead salts scares me a bit, I don't know if I could make sure the final product was completely clean of lead or lead ions, and even if that was possible, how does one make sure that their glassware is clean of it? Would one need to buy two sets of glassware just for working with such compounds? The only obvious cleanup I could think of was using H2S to react those ions to the insoluble PbS, but H2S is rather toxic as well.
While avoiding working with toxic compounds is probably impossible for anyone doing actual chemistry, I'd try avoiding mercury or lead and other ions that bioaccumulate, unless someone can show me a way to safely work with them and avoid contamination of the products (I have to say, I find the idea of using lead on carbon electrodes for electrolysis mildly attractive option to using expensive platinum electrodes, but I have no way to guarantee that I can avoid contaminating the product and glassware/equipment with lead impurities).


What about other routes to 1,4-butanediol, as it can be dehydrated to THF?

1. Besides the usual industrial routes, I've been thinking it might be possible to dehydrate ethanol to butadiene (see Lebedev's synthesis, runs at 400-450C, uses a variety of mixed metal oxide catalysts, most seemed like they could be made by the home chemist), there's another route to it via dehydration of ethanol with some tantalum-based catalyst on porous silica and milder temps (325-350C), but the catalyst seems like it'd be less accessible.
The main issue with using butadiene is that it's a gas, so you'd have to react it right away or use low temperatures (under -4.4C), it's also very flammable.
One might be able to brominate the butadiene with Br2, so that 1,4-Dibromo-2-butene would result, which should be sufficiently heavy to not be a gas anymore, pubchem says: 53.4C mp, 203C bp.
However, it's worth considering that if an excess of Br2 is used (+2 Br2), it would end up as 1,2,3,4-tetrabromobutane, and controlling the reaction conditions to avoid that could be challenging.
Then one could either hydrogenate this and then react with NaOH to get 1,4-butanediol, or react with NaOH, form some ester then hydrogenate that, or possibly even hydrogenate without forming the ester? I'm not sure what the conditions on those hydrogenations would be like, but I wouldn't expect them to be very mild. Maybe someone else can chime in and tell me if this route is hopeless or if I missed anything.

2. As with all the previous steps, it seems it's almost impossible to avoid the need for a hydrogenation step somewhere along the way, or if you can (such as THF point 4), you have to use a toxic catalyst that bioaccumulates.
Maybe it'd be possible to change the routes to use a reducing agent such as LAH or NaBH4, but given that THF is a solvent that is usually used in larger quantities, the expense of using such reagents would be unrealistic and be orders of magnitude more expensive than buying it or extracting it.

One option that didn't seem as bad seemed Vogel's prep of 1,4-butanediol from succinic acid (a Bouveault-Blanc reduction of an ester of succinic acid, see page 250, III.15, Vogel's textbook of practical organic chemistry), it still involves a reduction (with EtOH/Na), and it's probably more dangerous/flammable than reductions with LAH, although it seems more accessible to the amateur (and maybe slightly cheaper, more on this later).

What about obtaining succinic acid (again, since the goal is to make this from scratch)? Distillation of amber seems one route, but you'd probably need a lot of amber.
Carbonylation of ethylene glycol seemed interesting, but I believe most carbolynation conditions/pressures (+CO) are usually too extreme to be accessible without considerable effort to the amateur. A route involving hydrogenation of maleic acid exists too.
There was another route to succinic acid by biosynthesis with some genetically engineered microorganisms, but this doesn't seem like something that would be universally accessible or even easy to get one's hands on.
Another possibility was via malic acid (such as that isolated from apple juice), either by hydrogenation (again) with Raney Nickel, or some reduction with Red P and hydroiodic acid (would P, I2 work at all?). How much apple juice would you need? Consulting a paper on the topic claim that it's between 0.5-2g per 100g of apple depending on cultivar used, for most usually under 1g, which sounds a bit on the expensive side, but not completely out of reach. (paper: https://pdfs.semanticscholar.org/43a0/e1ff3ddacf8c565dbc4e8ddb0fbff6a292ec.pdf )

What about making succinic acid synthetically?
Recently I've learned about the reaction of halogenoalkanes and cyanide ions to form nitriles (such as https://www.chemguide.co.uk/mechanisms/nucsub/cyanide.html ), that is:
R-Cl or R-Br + KCN/NaCN -> R-C≡N + (K or Na)(Br or Cl) , and then hydrolizing ( https://www.chemguide.co.uk/organicprops/nitriles/hydrolysis.html ) the nitrile with either an acid or a base, such as:
R-C≡N + H2O + HCl -> R-COOH + NH4Cl
or
R-C≡N + H2O + NaOH -> R-COONa + NH3
then R-COONa + HCl -> R-COOH + NaCl
This seems like an excellent tool for making carboxylic acids from molecules that have fewer carbons than the target carboxylic acid.

The fact that it makes ammonia was also quite a pleasant surprise, but maybe it should not be that surprising as the hard step of forming the triple bond, or the fixation of nitrogen was already performed when the cyanide was prepared (and the fact that nowadays it's more common for ammonia to be involved in industrial or even amateur production of cyanide (such as from urea or cyanuric acid which itself can be obtained by decomposing urea to NH3 and the acid) rather than the more tedious fixation of nitrogen when making cyanide: as was attempted in the very early 1900s,
where some metal salt or carbide was burned to glowing red in a stream of pure nitrogen (see cyanamide process with calcium carbide, or for example, BaO + 3C + N2 -> Ba(CN)2 + CO, see Linus Pauling's College Chemistry (1950 textbook), or for a lot more practical details, see "The Cyanide Industry" by R. Robine and M. Lenglen (written in 1906), available on archive.org, which goes into a lot more details about the difficulties of this kind of direct nitrogen fixation.

Thus to get succinic acid, you'd start from 1,2-dichloroethane or some other 1,2-dihaloethane.
Wikipedia did point that it is made from ethene and chlorine with a iron(III) chloride catalyst, although both being gas phase, I don't know what difficulties would arise in practice.
And at this point I was wondering if it wouldn't make sense to bubble ethene through a solution of H2O with Cl2 dissolved in it (for example produced by electrolysis of NaCl in a diaphragm cell, by MnO2 and HCl or whatever else the chemist prefers), that is the reaction to make 2-chloroethanol (which was used industrially to make ethylene oxide (by adding Ca(OH)2 to the 2-chloroethanol), which can be hydrolized to ethylene glycol), in fact, it seems that 2-chloroethanol is predominantely produced if there's insufficient chlorine, while the 1,2-dichloroethane (so called "Dutch oil") if the Cl2 is in excess.
A while ago I've also seen a video of someone preparing 2-chloroethanol from ethylene glycol (so following the inverse direction the industrial process takes) and either HCl or Cl2 (I don't recall, but I could find out), which had gotten significant impurities of 1,2-chloroethane! So with controlling the process conditions (adding more Cl2 or more HCl) and increasing reaction time one can favor the 1,2-chloroethane.
Once one has the Cl-CH2-CH2-Cl (1,2-chloroethane), they could presumably react it with KCN (would NaCN work as well? if not, why not?), get the nitrile: N≡C-CH2-CH2-C≡N, and hydrolize that with either NaOH or HCl to COOH-CH2-CH2-COOH, that is, succinic acid.
Around the time I was researching this reaction, I've noticed that the literature already considered this preparation and that it was fairly standard, although that they used 1,2-dibromoethane, for example Hopper Wheeler's "Systematic Organic Chemistry Cumming" (page 125) as available on this site's library: https://www.sciencemadness.org/library/books/Systematic_Organic_Chemistry_Cumming_Hopper_Wheeler.djvu which seems to have been mentioned online too: http://www.prepchem.com/synthesis-of-succinic-acid/ (example 2)
The bromo variation seems more convenient, with it unlike bubbling ethene through water with chlorine dissolved in it, the byproducts of bubbling ethene through Br2 are usually only 1,2-dibromoethane, rather than both 2-chloroethanol and 1,2-dichloroethane. in fact, one would see exactly when the reaction was finished as the bromine color would disappear from the solution, and it serves as a way to identify the presence of double carbon bonds (alkenes, that is C=C), also see https://en.wikipedia.org/wiki/Alkene#Halogenation
I would like to know if the reaction with 1,2-chloroethane would work as I envisioned either way (if someone can chime in to confirm or deny it?), but it seems the bromo variant is more convenient. While bromide salts are not as available as chloride salts, I do believe they can be found in pool stores at the very least.



Thus the proposed route to THF or butanediol is as follows:
1. Ethene is obtained from Ethanol and sulfuric acid (or potentially even by passing ethanol vapours over a heated(?) glass tube packed with SiO2/sillica gel beads ( https://www.sciencemadness.org/smwiki/index.php/Ethylene says aluminium oxide should be used intead), I recall someone claiming this works, but I can't recall the reference). Example: http://www.prepchem.com/synthesis-of-ethylene/
The ethene is lead into a solution of bromine until the color in it is gone. This yields 1,2-dibromoethane.
Alternative possibilities: use water with chlorine dissolved in it and make "Dutch oil", excess chlorine should be used. same, but instead of ethene, use ethylene glycol and maybe HCl/Cl2 (if someone is interested, I'll try to find the video showing the ethylene glycol route, I believe it was linked/posted on this forum).
2. Follow preparation 61 in Hopper Wheeler's "Systematic Organic Chemistry Cumming" (page 125) to make succinic acid from 1 and a cyanide salt:
---
Preparation 61.--Succinic acid [Butan di-acid].
COOH.CH2.CH2.COOH. C4H6O4. 118.
100 gms. (1 mol.) of ethylene dibromide and 75 gms. (excess) of potassium cyanide in alcoholic solution are refluxed on a water bath in a 750-c.c. round-bottomed flask until potassium bromide ceases to separate out from the solution.
The latter is then cooled and filtered ; 60 gms. (2 mols.) of solid caustic potash are added, and the mixture again refluxed on a water bath in a fume cupboard until the strong evolution of ammonia gas begins to slacken.
The flask is then cooled, and the contents are acidified with dilute hydrochloric acid and carefully evaporated to dryness.
The dry powdered residue is repeatedly extracted with absolute alcohol, and the extract distilled on a water bath.
The succinic acid remains behind in small crystals ; it is recrystallised from hot water, decolorising if necessary with a little animal charcoal.
CH2Br.CH2Br + 2KCN = CH2(CN).CH2.CN + 2KBr.
(CH2CN)2 + 2KOH + 2H2O = (CH2COOK)2 + 2NH3
(CH22COOK)2 + 2HCl = CH2COOH + 2KCl
.CH2COOH
Yield.--80% theoretical (50 gms.). Colourleus prisms; soluble in water, alcohol, and ether ; insoluble in chloroform ; sublime above 100 ° without decomposition;
M.P. 185°; at 235° decompose forming the anhydride. (P. R. S., 10, 574; A., 120, 268.) For the isolation of ethylene dicyanide, see p. 151.
---

I'd be interested to know if NaCN would work as well, or why did the author prefer using KOH and HCl rather than HCl (was it so that they'd know when the reaction completed as the ammonia gas would stop evolving?).
I'd also like to know how well would this reaction work with 1,2-chloroethane

Alternate route would be from malic acid extracted from apple juice/apples, but this seems uneconomical.
3. Follow preparation III.15 from "Vogel's textbook of practical organic chemistry" to make 1,4-butanediol from succinic acid:
---
III,15. TETRAMETHYLENE GLYCOL (1:4-BUTANEDIOL)
This is an example of the reduction of an ester of a dibasic acid to the corresponding glycol (Bouveault-Blanc reduction):
(CH2)2(COOC2H5)2 + 8H ---(Na + C2H5OH)---> (CH2)2(CH2OH)2 + 2C2H5OH
Introduce a two-way adapter (Fig. II, 13, 9) into the neck of a 3-litre round-bottomed flask;
fit a separatory funnel into one neck and two efficient double surface condensers in series into the other.
Place 60 g. of clean dry sodium (the surface layer must be completely removed--see Note I to Section III,7) in the flask,
and add from the separatory funnel (protected by a drying tube) a solution of 35 g. of diethyl succinate (1)
in 700 ml. of "super-dry" ethyl alcohol (Section II,47,5) as rapidly as possible consistent with the reaction being under control;
it may be necessary to immerse the flask momentarily in a freezing mixture.
When the vigorous action has subsided, warm the mixture on a water bath or in an oil bath at 130° until all the sodium has reacted (30-60 minutes).
Allow to cool and cautiously add 25 ml. of water (2); reflux for a further 30 minutes to bring all the solid into solution and to hydrolyse any
remaining ester.
Add 270 ml. of concentrated hydrochloric acid to the cold reaction mixture, cool in ice, filter off the precipitated sodium chloride
and treat the flitrate with 300 g. of anhydrous potassium carbonate to free it from water and acid.
Filter the alcoholic solution through a large sintered glass funnel, and extract the solid twice with boiling alcohol.
Distil off the alcohol from the combined solutions; towards the end of the distillation solid salts will separate.
Add dry acetone, filter, and distil off the acetone.
Distil the residue under diminished pressure, and collect the tetramethylene glycol at 133-135°/18 mm. The yield is 13 g.
Notes.
(1) The preparation may be adapted from the experimental details given for Diethyl Adipate (Section III,99). Another method is described in Section III,100.
(2) Alternatively, the following procedure for isolating the glycol may be used.
Dilute the partly cooled mixture with 250 mi. of water, transfer to a distilling flask, and distil from an oil bath until the temperature reaches 95°.
Transfer the hot residue to an apparatus for continuous extraction with ether (e.g., Fig. II, 44, 2).
The extraction is a slow process (36-48 hours) as the glycol is not very soluble in ether.
(Benzene may also be employed as the extraction solvent.)
Distil off the ether and, after removal of the water and alcohol, distil the glycol under reduced
pressure from a Claisen flask.
---

For the ester of diethyl succinate, I would assume that one can simply form the ester of ethanol and succinic acid in some acid catalyzed/dehydrating conditions, however I'll paste the
prep from the same book, page 409:
---
Diethyl succinate. Reflux a mixture of 58 g. of A.R. succinic acid,
81 g. (102,5 ml.) of absolute ethyl alcohol, 190 ml. of sodium-dried
benzene and 20 g. (11 mi.) of concentrated sulphuric acid for 8 hours.
Pour the reaction mixture into excess of water, separate the benzene-
ester layer, and extract the aqueous layer with ether. Work up ths
combined ether and benzene extracts as described for Diethyl Adipate.
B.p. 81°/3 mm. Yield: 75 g. The boiling point under atmospheric
pressure is 217-218°.
---

The add diethyl adipate preparation is included here for the sake of the referenced workup (page 409, same book):
---
III,100. DIETHYL ADIPATE (Benzene Method)
Place 100 g. of adipic acid in a 750 ml. round-bottomed flask and add
successively 100 g. (127 ml.) of absolute ethyl alcohol, 250 ml. of sodium-dried benzene
and 40 g. (22 ml.) of concentrated sulphuric acid (the last-named cautiously and with gentle swirling of the contents of the flask).
Attach a reflux condenser and reflux the mixture gently for 5-6 hours.
Pour the reaction mixture into excess of water (2-3 volumes), separate the benzene layer (1), wash it with saturated sodium bicarbonate
solution until effervescence ceases, then with water, and dry with anhydrous magnesium or calcium sulphate.
Remove most of the benzene by distillation under normal pressure until the temperature rises to 100° using the apparatus of Fig. II, 13, 4 but
substituting a 250 ml. Claisen flask for the distilling flask; then distil under reduced pressure and collect the ethyl adipate at 134-135°/17 mm.
The yield is 130 g.
Note.
(1) One extraction of the aqueous solution with ether is recommended.
---

4a. THF from 1,4-butanediol
https://doi.org/10.1002%2F14356007.a26_221 Müller, H. (2000). Tetrahydrofuran. Ullmann’s Encyclopedia of Industrial Chemistry.
Claims that the cyclization proceeds easily:
"The saturated diol is very readily cyclized to THF with elimination of water by acid catalysis above 100C. Suitable catalysts include inorganic acids, acidic aluminum silicates, and earth or rare-earth oxides.
1,4-butanediol --(H+)t>100C--> THF
Wikipedia claims H3PO4 is usually used and the reaction proceeds easily (delta H = -13.4kJ/mol for this reaction). So it's rather similar to conditions of forming esters and ethers.
"Quantitative conversion and a yield of almost 100% can be achieved in an atmospheric-pressure, continuous process with aluminum oxide as the catalyst provided the THF is continuously distilled out of the reaction mixture as it forms
and pure 1,4-butanediol is fed into the reactor at a rate equal to its rate of consumption. The amount of conversion per unit amount of catalyst is very
high. Crude butanediol can be converted into THF very selectively and with little added energy by a medium-pressure process described by BASF [12]. The THF – steam mixture obtained
from cyclization is first distilled in a rectification column to give the corresponding azeotrope (5.3 wt% water, bp 62.3 ◦C). Treatment with alkali hydroxide [13] and subsequent distillation provides anhydrous THF. The azeotrope problem can also be circumvented industrially by distillation under pressure."
[13] - 13. IG Farben, DE 713 565, 1939 (W. Reppe, H.-G. Trieschmann). https://patents.google.com/patent/DE713565/en https://patents.google.com/patent/DE713565C/en unfortunately I was unable to find a way to download or view this patent.
https://patents.google.com/patent/EP0153680A2/en there is this which is accessible, claims an azeotrope with water forms at 96% THF (4% water) > The azeotropic mixture has been dewatered in a conventional per se, for example by means of solid dehydrating agent or by extractive distillation. In this case, (% wt 99.9.) Tetrahydrofuran was of very high purity obtained.

Although the fact that THF isn't anhydrous from this process may pose a problem for its use as a solvent for LAH/NaBH4 reductions or the grignard reaction, it's probably fine for OP's needs (step 4b)
How would one break the azeotrope, is it just distillation after adding a strong base (such as NaOH) to it or some other dehydrating agents (H2SO4? molecular sieves?), would some form of salting out work, by using some salt insoluble in THF but soluble in water?


4b. As OP wanted, GBL from 1,4-butanediol https://en.wikipedia.org/wiki/Gamma-butyrolactone#Preparation
"GBL is produced industrially by dehydrogenation of 1,4-butanediol.[4] This route proceeds via dehydration of GHB. In the laboratory, it may also be obtained via the oxidation of tetrahydrofuran (THF), for example with aqueous sodium bromate.[8]"
Seems to use acid catalysts to dehydrate it, see: https://doi.org/10.1002%2F14356007.a04_495 see page 2 for production:
"Preheated 1,4-butanediol vapor is introduced into a hot stream of circulating hydrogen and passed at atmospheric pressure through a bed of copper catalyst at temperatures between 180 and
240 C (Figure 1). The yield of butyrolactone is approximately 95 %. The reaction takes place via g-hydroxybutyraldehyde [25714-71-0] [7].
The byproduct hydrogen off-gas requires only simple purification before reuse (e.g., catalytic methanization of carbon monoxide impurities).
The crude butyrolactone separated from the recycle gas stream contains small amounts of byproducts, including 1,4-butanediol, butyric acid, and high boilers, from which butyrolactone is separated by distillation
Butyrolactone itself is noncorrosive and can be handled in carbon steel apparatus. However, where parts of the synthesis or distillation vessels and pipes come into contact with hot crude product containing butyric acid, they must be made of stainless steel."
[7] is "S. Oka, Bull. Chem. Soc. Jpn. 35 (1962) 986 - 989." I haven't attempted looking that article up yet.

I'd imagine one could generate the hydrogen either by electrolysis or action of HCl on some sacrificial metal (that could be recycled by electrolysis after) and the 1,4-butanediol heated to the required temperature,
but without having tried the reaction myself or seen someone else do it, I can't say how practical it'd be. I'd also imagine you'd need to first flush with an inert gas to avoid the potential explosion hazard from H2 and O2 mixing at those temperatures.

This does seem more involved than expected, maybe a lab scale preparation of GBL via THF and sodium bromate or some other preparations you can find on erowid/rhodium would be much easier? I wasn't going to repost it, but a quick lookup gave these:
https://erowid.org/archive/rhodium/chemistry/thf2gbl.html yields seem to be so so, but usually above 50%
https://erowid.org/archive/rhodium/chemistry/bd2gbl.html from 1,4-butanediol with copper chromite, 80% yield, with 10% unreacted 1,4-butanediol which presumably can be recycled, even better.
https://erowid.org/archive/rhodium/chemistry/bdo2gbl.html another one, seems a wide variety of oxidants work, with reasonably good yields again.
https://erowid.org/archive/rhodium/pdf/bd2gbl.pdf this one from 1,4-butanediol and NaOCl, but despite the very accessible oxidant, it requires an inert argon atmosphere



I do believe this route to THF is OTC and should be possible to be made in any location in the world no matter the restrictions on chemicals:
1. Ethanol can be prepared by fermentation of sugar, distilling, can be made anhydrous by salting out and distilling again.
2. KCN or NaCN can be prepared from Urea (fertilizer), rust (iron oxide), charcoal, sodium or potassium (bi)carbonate (the carbonates are usually available in most places except maybe in some places in south america, in which case, they could be made from table salt, diaphragm electrolysis to the hydroxide, and bubbling CO2 or letting it absorb slowly from atmosphere). If urea isn't available, various organic nitrogen waste can be used, or some sources of ammonia salts might work as well, but the organic waste route is inconvenient and smelly, a few other preparations of cyanides exist besides this, but they're all somewhat inconvenient, although possible, but slow and low yielding (such streams of clean N2, maybe produced by using hot glowing copper, or just buying a tank of it that was industrially obtained by distilling liquefied air).
3. Sodium metal can be prepared from OTC materials:

a. NurdRage's method (see his youtube channel, or look on the sciencemadness wiki) which involves using menthol (or some tertiary alcohols) as a catalyst, NaOH and Mg shavings, and some mineral oil as the solvent, temps around 200C. He also published a route that is similar Mg and NaOH thermite reaction, followed by using dioxane (made from cyclized ethylene glycol using H2SO4 as a dehydrating catalyst) as a solvent to purify it into sodium spheres that could then be used.
This method is very OTC, but it produced waste magnesium oxide/hydroxide, so the costs may add up, while you'd think recycling magnesium is easy, the temperatures and conditions for electrolyzing it back are double or more than those required for electrolyzing NaOH or NaCl, and thus just electrolyzing sodium hydroxide or sodium chloride is more cost-effective/sustainable longterm:
b. len1's book: "SMALL-SCALE SYNTHESIS OF LABORATORY REAGENTS" by LEONID LERNER describes an electrolytic method for production of Sodium metal (as well as Lithium, it even has a chapter on LiH, NaH and LAH, and far more)
The latter method seems more cost-effective long-term, unless one has a lot of magnesium metal they have no need for lying around (see a).
I've seen a few other ways of making sodium, but they seem unpractical or maybe not even feasible, for example, by explosive(!) decomposition of sodium azide (which could be made via hydrazine and sodium nitrite), I can't imagine how this could be made to work practically.
c. A more practical method that isn't a or b, seemed to involve carbothermal reduction of sodium carbonate:
https://www.metallab.net/Na.php "Na2CO3 (liquid) + 2 C (solid) --> 2 Na (gas) + 3 CO (gas)" at 1200°C, the setup looks quite "ghetto", but it might be quite practical, I'm curious about purity of the sodium, but I'm sure the process could be refined. Due to the temperatures involved, it requires an inert gas like argon.

4. I did not notice solvents or reagents that cannot be obtained or prepared from readily accessible materials, and some can be substituted (for example, benzene might be obtained from decarboxylating sodium benzoate, or pyrolysis of PET, or a from scratch synthesis by trimerization of acetylene (I've seen a few successful attempts of the latter), although neither process is completely clean).
Bromide salts are usually accessible, but if bromide is unavailable, the "Dutch oil" (1,2-dichloroethane) route might work as well.
For 3c (sodium), argon can be obtained from some welding supplies, but is difficult to make yourself (distillation of liquefied air), although other routes do exist (a, b).

What are the disadvantages?
It uses toxic cyanide salts, with sufficient care, it should be possible to do it safely, although there's always a risk. The cyanide route scares me far less than the soluble lead salt route, at least the toxicity of cyanide is not long lasting, you either survive and are fine or you don't (be very careful and take all the precautions), while exposure to lead salts may end up hurting more years later.
The reduction of succinic acid needs 4 mol of sodium for every mol of succinate, so it is a bit expensive (needs quite a bit of sodium), however while it won't compete with the industrial method (about 10 times as expensive than buying THF bulk by the barrel), it is cheaper than buying from a regular lab supplier, lab supplier prices end up being higher than making it by this route until after you buy about 30l of THF (at least given the suppliers I've looked at).
Another problem is that the reduction of succinic acid with sodium in ethanol is very water sensitive (ethanol must be completely dry) and is a fire/explosion hazard, much care must be taken.

Advantages? No need for reduction catalysts like Pd/C or Raney Nickel or expensive reducing agents.

I do think the RaNi hydrogenation or furan is likely much cheaper and easier route to THF than this, and probably much safer (no toxicity besides that of furan/furfuryl, and certainly no fire hazard of sodium in ethanol), although it requires one to take the time or money to make or buy a hydrogenation apparatus or autoclave, and maybe a ball mill if making Raney Nickel, someone should see if Urushibara nickel would at least work as it's much easier to prepare.
I mostly tried to see if a way to make it without hydrogenation existed (or a route that which did not require toxic lead salts) and this is what I was able to find out, I would really like to hear the comments if it's feasible or not and what mistakes I may have made, or if there's ways to make it even simpler. It will be a long while until I can actually try it out myself.

It's also worth noting that anyone making THF, should store it with some BHT ( https://en.wikipedia.org/wiki/Butylated_hydroxytoluene ) to avoid (explosive) peroxide formation, unfortunately this one might have to be bought or maybe a different antioxidant should be used instead, I don't know yet of a way to make BHT without the use of isobutylene (gas, bp -6.9C), although likely many other compounds can substitute.
I did not consider OP's route from GABA since my main interest is in THF rather than GBL, and even if a roundabout route from GABA existed, it would not be cost effective, given that one's use of THF is as a solvent and one might need at least few liters of it over the years in the lab, this is why reduction routes with more expensive reducing agents were not considered either.

[Edited on 3-8-2019 by etherealvapour]
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DReed123
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[*] posted on 4-8-2019 at 04:17


Functionally GHB and alcohol have nothing in common. Alcohol is a GABA-A modulator. It binds to an allosteric site near the primary receptor and potentiates the effects of natural GABA activity. Benzodiazepines also work this way.GHB agonizes GABA-B, which is minimally psychoactive, just sedating. Muscle Relaxants like Baclofen work this way. The psychoactive effects of GHB come from its agonism of the GHB Receptor (this is actually its name). Selective agonism of this receptor is actually seen to cause effects more commonly associated with stimulants than depressants. The increased libido and euphoria associated with GHB come from it's activity at the latter.

Almost all of the risk associated with GHB will come from mixing it with other CNS depressants. Withdrawal can be fatal:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2630388/

If you are looking for an OTC drug with similar effects you would be better off choosing nitrous oxide (provided you supplemented with sublingual B12 and don't put a mask on your face).
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[*] posted on 4-8-2019 at 08:20


I have successfully converted GABA into GBL via diazotation, in the past. Just dissolved GABA into dilute 20 % sulfuric acid (1,2 eq excess), cooled it down with ice and slowly added over the course of an hour a stoechiometric amount of NaNO2 solution always keeping it cool. Nitrogen gas evolution is prominent; after that I have brought the solution to a gentle boil for 10 minutes or so. Now normally you should distill the GBL or extract it with a solvent like ether; I neutralized the solution with Na2CO3, cooled it down overnight in the freezer and filtered the sodium sulfate out. You should get a yellowish dilute, still impure GBL solution.
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[*] posted on 4-8-2019 at 18:03


I imagine that h2so4 is easier to extract from than HCL solution.
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