Bromosafrole Phenylisopropylbromide

The third, and last, major category of X precursor is the halogen species. In the world of chemistry, scientists look to add things or change things with a molecule by exploiting 'functional groups'. So far we have been exploring the possibilities of the ketone functional group (P2P) and the nitro group (P-Nitropropene). And although there are lots of different things that can be considered functional groups, the only one left that really has any broad utility for the underground chemist is the halogen called Bromine. When one introduces a bromine into that magic beta carbon of safrole or allylbenzene (or however one can arrive at that point) one will get the following species:

Bromosafrole Phenylisopropylbromide

Bromosafrole is a great stepping stone to final product and was, in fact, the exact precursor used by Merck who was the first person to synthesize MDMA. Until very recently it was the defacto method that most underground chemists started out with (Someone-Who-Is-Not-Strike included) because, at first glance, it seems so simple and uses basic chemicals and equipment. Once someone has the bromosafrole, all one has to do is just swap out that Br with simple ammonia or methylamine and the deed is done.

But one has to get the bromine on the safrole in the first place, right? And that has proven more difficult than most people thought. Not because it is procedurally difficult, but because people have been misinformed on the subject for a long time.

The basic premise for making bromosafrole has been to mix safrole with Hydrobromic Acid (a.k.a. hydrogen bromide, HBr). That's it. The HBr does what is called a Markovnikov addition reaction whereby the HBr sees the allyl double bond of safrole and preferentially attaches its hydrogen to the gamma carbon and its bromine to the middle beta carbon (don't ask).

But the key to success is getting the right form of HBr for the reaction. A lot of people start off with the CA abstract that uses aqueous 70% HBr as the reagent (this abstract is essentially a rewrite of Merck's original patent) [59]. The following is the write up:

"Safrole (5.3g) added dropwise at <fC to 21 g. 70%HBr, the mixt. left 14 hrs. at 0°C, poured on ice, extd. with Et20, and the ext. Distilled in vacuo yielded 97% 3,4-CH202C6H3CH2CHBrMe:'

97% yield sounds great. But where the hell can one get 70% HBr? Certainly no place that Strike is aware of. It does not exist in other words. Nor does Strike know how any of these folks were able to make a supersaturated aqueous solution of HBr. All commercially available hydrobromic acid solutions are 48% HBr which happens to be the constant boiling point percent for that species in water (please don't ask).

Some people think that 48% aq. HBr is good enough and, until recently, some underground chemistry texts agreed. But it is not! The 48% is only strong enough to promote what is called acid catalyzed hydration (don't ask) when the medium it is in is water. That means that a water molecule (an OH) will add instead of a Br.

The problem really isn't the concentration of the HBr, but rather is the result of the HBr being in water. As long as there is a significant amount of water present in the reaction mix with safrole, that water is going to compete with bromine for that juicy beta carbon on safrole. And it's gonna win, too. The answer is to use nonaqueous HBr solutions.

For the past year Strike had been in consultation with contract labs over the making of phenylisopropyl alcohols using sulfuric acid and allylbenzenes (don't ask). The lab owners would listen patiently as Strike primitively described how and why an OH should go on the beta carbon. And without exception, the lab owners would point out to Strike that the best way to get an OH on the beta carbon would be to put a Br there first. "But Strike don't wanna put a Br there first" Strike would say, "Strike wants the OH put on directly using sulfuric acid!" The lab guys had to do what Strike said because Strike was holding all the money (...a fool and her money etc.). But out of curiosity Strike asked how they would get that Br on the beta carbon. Every one of them said it was simply a matter of using the 48% HBr in acetic acid. They even showed Strike their stock solutions (usually from Aldrich or Fisher).

Currently, there are commercially available 48% or higher HBr solutions in acetic acid. These work just fine. They really do! The acetic acid is usually used more as a solvent than an acid. It allows the water-loving HBr and the water phobic safrole to mingle with each other in a very positive way. If one cannot get a ready-made solution of HBr in acetic acid then one can make one quite easily.

To make her own HBr solution the chemist needs to go down to the local specialty gas supplier. These sorts of businesses sell tanks of oxygen to hospitals, acetylene tanks to welding shops and, yes, HBr to underground chemists. The chemist places 200g of acetic acid in a small PP container or flask and then weighs the flask with its contents. Next, the flask is stirred in an ice bath tray that has just a small amount of ice to keep the contents cool and

HBr from the tank is slowly bubbled into the acetic acid. Ever so often the chemist will stop the bubbling and reweigh the flask to see how much weight in HBr it has gained. Ideally, the chemist would like to have around 150g of HBr in that acetic acid which is now quite orangy in color.

Another way would be to generate ones own HBr gas. If you were to take a look in the Crystallization section of this book one would see that the apparatus used is essentially an HCI gas generator. Substituting the commercially available 48% aq. HBr instead of HCI will give one dry HBr gas instead! That gas can be channeled directly into acetic acid just like above.

The last thing to remember is that the more HBr one packs into that acetic acid, the greater and quicker the yield will be. 70% HBr is still the paragon and should be strived for always. So with the proper HBr solution in hand the evil chemist can proceed with the conversion of safrole.

METHOD #1: To proceed, the chemist uses her concentrated homemade solution that she made above or uses ~350g of any concentrated HBr reagent, places it in an appropriately sized flask and places the flask in an ice bath [60, 154], The setup is going to look exactly like the one seen in fig. 9. In the separatory funnel is placed 137g of safrole or 100g allylbenzene. The HBr/acetic acid solution is stirring in the ice bath til it is between 5-10°C (if it gets too cold the acetic acid will turn to ice) then the safrole is slowly dripped in. The oil will bead up on the surface for just a bit but will dissolve quickly into the cold acid mix. Good, constant stirring assures that everything comes in contact with everything else. After addition is complete the solution is a dark orange and is allowed to

come to room temperature slowly by letting the ice melt away. Then the solution is covered with foil and stirred at room temperature for 24 hours. After such time the solution will be a single layered burgundy solution. The chemist pours this solution into a container of 300mL cold water and 500g crushed ice made earlier from dH20. Things will look lavender in color with the heavy bromo-safrole sitting at the bottom. The bromo-safrole is separated from the water and the water extracted once with 100mL ether or benzene which is then added to the bromo compound. The bromosafrole/solvent is washed once with clean dH20, once with 3% sodium carbonate, then dried through Na2S04. What the chemist has now is a dark red bromo-safrole compound in some solvent. The chemist removes the solvent by distillation then vacuum distills the bromo compound over to get a clear, slightly orange bromo-safrole (yield=90%). Actually, the bromo compound is pretty clean as is and can be, if desired, used as is. A chemist who is mindful of the potential of this bromo-safrole would make far bigger batches than the amounts given above. This bromina-tion procedure is perfectly suited for large reactions.

If the chemist wants to know whether her final product is bromo-safrole and not just a bunch of unreacted safrole there is a simple little test she can do. Safrole is soluble (will dissolve in) cold concentrated sulfuric acid. But bromosafrole is insoluble in it. So the chemist can take a shot glass full of straight-from-the-bottle 96% H2S04 and place it in the freezer until it's ice cold. Then she takes it out and drops a few drops of mystery product into it. If the oil dissolves then the stuff is unreacted safrole. If the oil drops to the bottom and does not dissolve it's the goods.

METHOD #2: Speed chemists have used hydroiodic acid (HI) for years to reduce ephedrine to meth. So when the government placed HI on the restricted list, speed chemists took to making the HI themselves. One of the ways they used was to make HI in DMSO (dimethylsulfoxide, a common solvent) by reacting Nal or Kl with sulfuric acid. This a standard way to make both HBr or HI in water (see the Chemicals section of this book) except these speed chemists were using the non-aqueous solvent DMSO instead of water.

When Strike first started the Hive web site Strike was sent a newsgroup post by a very famous underground chemist called Pugsley. Pugsley had apparently been toying with the idea of in situ (in the pot) production of HBr for making bromosafrole. The following is her recipe. Strike knows it works because Strike's friend in Houston tried it out in her accredited and licensed university lab and gave it the old thumbs-up!

"Subject: Pugsley's bromosafrole prep > From: no-[email protected] (Anonymous) > Date: 1996/06/28 > Message-Id: Newsgroups: alt.drugs.chemistry > [More Headers]

Here is the only bromosafrole (or bromo propenylbenzene) synthesis you will ever need. It proceeds totally anhydrous with pure reagents, and generates no obnoxious fumes to give you away. More than likely, this will spur DEA to add new watched chemicals (like what isn't watched already- air, water, ?) To 100 ml of chilled DMSO add 7.8ml conc. H2S04 (i.e. drain cleaner). To this add 30g of NaBr. Stir well and repeatedly. Solution will turn orange as all the NaBr is turned into Na2S04. Do not filter, leave crystals alone in case there is some unreacted NaBr left. If the H2S04 and DMSO is anhydrous, so will the HBr be anhydrous. Add 5 ml of sassafrass oil. Or scale qty of everything up for more sassafrass. Let sit at room temp. Don't bother to filter out crystals, in case there is unreacted NaBr. In 1 or 2 days solution will proceed as in Fester's turning green, then purple, then gradually burgundy. To understand why this works so well, see Fieser and Fieser "Reagents in Organic Synthesis" under DMSO monograph. Note that there are two pathways for HBr to react. Via an ionic mechanism gene rates the desirable compound. Via a free-radical route forms terminal bromo compound, which cannot be used (you can try for interesting analogue, but who cares now that all mind altering chemicals are illegal under the Analoges Act, including all those in everyone's brains- imagine, even Jesse Helmes committing felony if he has any brain cells left). The crude sassafrass oil contains eugenol, a phenolic compound which inhibits free radical reaction. Thus you will get better product if you don't purify out safrole. Also keep reaction mixture away from air and UV light, both generate

free radicals. The final mixture gets 500-1000ml of water added. The crude bromosafrole which settles to the bottom is seperated without adding any organic solvent. If you cool it it gets pretty sticky and syrupy so the water layer can be just poured off."

One need not inhibit oneself by using HBr. One can use Nal or Kl to make HI which is even better than HBr in any of these recipes. Iodine adds much better and swaps out with the amines much better. Yield are much higher! The other thing to notice is that reaction carries itself out in DMSO. Seems logical to believe that one could bubble their HBr gasses into this solvent instead of acetic acid.

METHOD #3: This is not really a method. It is more of an idea Strike and others have been toying with. Eleusis had been supporting the idea that one could make use of the common 48% aq HBr if one employed the technique of 'dehydration'. We remember that the water was competing with the Br in the normal 48% solution. But the literature demonstrates that in conditions such as this, a competing acid can strip away the water (dehydrate) from the beta carbon allowing the Br a second chance to pop in.

Fester [18] has made this modification to his recipe by promoting the idea that bubbling HCI gas into the safrole/48% aq HBr reaction mix one can affect dehydration allowing dominant bromination to occur. Strike does not know if that actually works. Could be. But what Strike and Eleusis draw on are the examples given by Vogel [37 p277].

When Vogel wants to brominate something using regular old 48% aq. HBr, he has sulfuric acid already present in the pot. The following is a representative recipe from his book. Just read it. Strike does not expect you to get the inference right away. Strike will explain Strike's interpretation afterwards.

"Ill,35. Sec-Butyl Bromide (HBr-H2S04 Method) - 148 -

To 250g. of 48 per cent, hydrobromic acid contained in a 500ml. round-bottomed flask add 75g. (41 ml.) of concentrated sulphuric acid in portions with shaking (1); some hydrogen bromide may be evolved. Add 88g. (110ml.) of sec-butyl alcohol, followed by 60g. (32.5ml.) of concentrated sulphuric acid in several portions with shaking, and finally a few chips of broken glass. Attach a reflux condensor to the flask and reflux the mixture gently on a wire gauze for 2-3 hours; during this period the formation of sec-butyl bromide is almost complete and a layer separates above the acid. If the preparation is carried out in the open laboratory, fit an absorption device (compare Fig. II, 13,8 and Fig. 111,28,1) to the top of the condenser i order to absorb any hydrogen bromide and sulfur dioxide which may have evolved. Allow the contents of the flask to cool, remove the condensor and set it for downward distillation; connect the condenser to the flask by means of a wide (7-8mm. diameter bent glass tube. Distil the mixture until no more oily drops of sec-butyl bromide to pass over (30-40 minutes). Transfer the distillate to a separatory funnel and remove the halide which forms the lower layer. Wash it successively with water, an equal volume of concentrated hydrochloric acid (2), water, 5 per cent, sodium bicarbonate or sodium carbonate solution, and water. Separate the water as completely as possible and dry with 2-3g. of anhydrous calcium chloride or anhydrous magnesium sulphate; the desiccant should be left in contact with the bromide for at least 30 minutes and shaken occasionally. Filter the dried product through a small funnel supporting a fluted filter paper or small cotton wool plug into a 200ml. distilling flask, add a few chips of porous porcelain and distill either from an air bath (Fig. II, 5,3) or on an asbestos-centered wire gauze. Collect the portion boiling at 100-103°. The yield is 155g.

Notes. (1) the acid mixture may be prepared (compare Section 11,49,1) by placing 120g. (37.5ml) of bromine and 130g. of crushed ice in a 500ml. flask, cooling the latter in ice, and passing sulphur dioxide (from a siphon of the liquified gas) into the bromine layer at such a rate that the gas is completely absorbed. The flask is shaken occasionally, and the flow of gas is stopped immediately the red colour due to free bromine has disappeared; the mixture - 149 -

will then have a yellow colour. The resulting mixture is equivalent to 250g. of 48 per cent, hydrobrvmic acid to which 75g. of concentrated sulphuric acid have been added; it need not be distilled for preparation of sec-butyl bromide.

Owing to the comparatively negligible difference in the cost of bromine and the equivalent quantity of constant boiling point hy-drobromic acid, there is little to be gained—apart from the instructional value-- in preparing the hydrobromic acid from bromine in the preparation of alkyl bromides.

CAUTION. Bromine must be handled with great care and in the fume cupboard. The liquid produces painful burns and the vapour is unpleasant. Bromine burns should be treated immediately with a liberal quantity of glycerine. If the vapour is inhaled, relief may be obtained by soaking handkerchief in alcohol,holding it near the nose.

(2) The crude bromide contains a little unchanged alcohol and is said to contain some n-butyl ether (b.p. 141°). The former is removed by washing the concentrated hydrochloric acid and this purification process is satisfactory for most purposes. Both the alcohol and the ether are removed by washing with 11-12ml. of concentrated sulphuric acid; the butyl bromide is not affected by this reagent."

You see that substrate they were using: "sec-butyl alcohol"? Well to Strike that looks just like MD-P2Pol:

oh safrole he is starting with. It is an OH alcohol!". That's true. But in this instance it does not make a difference. We know that at 48% aq concentration an OH is going to end up on the beta carbon anyway. So starting with an alcohol will make no difference. The clincher is the presence of the H2S04. It is there not only to strip off the existing OH, but to keep it off so that bromination becomes dominant.

So if one were to replace sec-butyl alcohol in the recipe above with an equimolar amount of safrole in the above reaction, Strike will wager that a positive bromination experience will occur. And all this using the very common 48% aq. HBr! The only difference being that once the reaction mix had cooled, one should do either of two things: (1) distill as described except the bromosafrole will be the last thing to come over (not the first), or (2) flood the reaction mix with water to bring the product out of solution after which it can be physically separated by decanting or sep funnel or some such shit.

Anyway, this is just an idea. But in case one feels inclined to use it or make HBr gas from 48% aq. HBr, Strike has provided quite a few recipes for the manufacture of the 48% in the Chemicals section.

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