Safrole bromination variation

[endo1]

OKEE

I have not seen a bromosafrole post in a while so here is a detailed write up of SW's safrole bromination variation. I like this variant because very little HBr fumes are produced, not much labour involved and the yields are nice. The drawback is it requires tech grade HBr in GAA.

To a small "gem" jar is added a stir bar, 500 ml of FREEZER COLD technical grade 33% hydrogen bromide in glacial acetic acid and 325 ml of sasafrass oil (unknown safrole %) in that order. The jar is promptly capped tightly and shakin until homogenous. The reactants are then placed on a magnetic stirrer inside of a deepfreeze and stirred vigorously for 24 hours (take care that the stirbar is not stuck to the inside of the lid!). The contents of the jar are allowed to defrost just enough to pour if solids have formed and then they are poured in to a large sep funnel containing about 300 grams of crushed ice. Sep funnel is occassionally agetaded until ice is all melted. Organics are extracted with 1250 ml of toluene and the acid water layer is discarded. The toluene/bromo mix is then washed with 500ml of water and a little baking soda is added if necesary untill a clean seperation of the water and organics is observed (carefull of foaming and pressure build up). The water layer is drained and discarded. 500 ml of fresh water is added. Baking soda is added slowly with swirling and venting and then, eventually, shaking and venting bewtween adds of baking soda untill saturation of water is observed by a small amount of undissolved solids. water layer is discarded and a second "baking soda wash" is performed in exactly the same way as above. Solvent is distilled off under aspirator vacuum and recycled (see footnote 1). The next 2 fractions are distilled off also under aspirator vacuum (see footnote 2) and then the bromosafrole is distilled under vaacuum pump reduced atmosphere to give about 350 grams of fairly clear bromosafrole.

footnotes:
1: this toluene may contain some HBr so it is used only for the same purpose again.
2: It seems fairly evident that there are two main fractions after the toluene and before the bromosafrole comes. A tiny bit of unreacted safrole at 110 and then something else at about 130-140 under SW's aspirator vaac, it's got a red tinge to it and is fuming a little bit of HBr and smells kind of sweet/irritating, maybe isosafrole or brominated isosafrole? xxx/HBr azeotrope ? Whatever it is, SW thinks that this stuff is what turns some peoples bromosafrole red and is kind of hard to seperate from bromosafrole. It seems the only time SW's bromo has a red color to it is when he collects his bromo too early.

Other Notes:
- Keep in freezer if a wash/distill cannot be performed immediately.
- Attempts have been made to use homemade HBr in GAA but problems occurred due to the high mp (the shit kept freezing up bad!) Although the mp listed in the MSDS is +17c (I think.... hmm why is it higher than just strait up GAA?), for some reason the technical grade obtained by SW never freezes in the freezer if the container is not opened i.e. the factory seal is not broken (The 500ml bottles of tech HBr in GAA are obtained from supplier). Also, very little freezing occurs during the reaction when tech grade is used for some reason.
- Sorry, not sure exactly what temps the reaction actually runs at. Just a regular old deepfreeze. Maybe about -5c?
- Attempts have been made to use a flat bottom erlenmyer flask to do the reaction but the stirbar created too much heat and or the stirrer transferred too much heat so the concave bottom of a jar was found to be more suitable.

[3base]

respect endo1, i like it !

i hope your recipe will find its way on rhodiums compilation:

https://www.thevespiary.org/rhodium/Rhodium/chemistry/halosafrole.txt

> Attempts have been made to use homemade HBr in GAA

how did you made HBr in GAA ?

None

(http://www.3base.i-p.com/safrole.plants/)

[ClearLight]

could the 57% hydroiodic acid made as per the recent post be used instead of HBR in this method?
Infinite Radiant Light - THKRA

[endo1]

how did you made HBr in GAA?


Sorry, not sure how it was made. It was someone elses homemade HBr in GAA in this case. I do believe it was mentioned that sodium bromide was involved though. Do you think it might have been bunk? It doesn't seem to be bunk as it's fuming heavilly w HBr although it is quite a bit darker than the tech grade and has a red color to it. The makers of it claim it to be higher than 33% but SW can't seem to prevent the freezing so a higher temp has to be used and then the finished product smokes like a SOB in the still. He still has some of this homemade HBr in GAA and would love to be able to put it to use though if anyone has any suggestions, they would be greatly appreciated....

SW used to use P2O5 and aqueous HBr when making his own HBr gas but used toluene as a solvent and the oil was already mixed in before gassing. Yields were crappy (probably mostly because GAA should've been used instead for solvent) and it was shitty labour.

[3base]

> it is quite a bit darker than the tech grade
and has a red color to it.

the red color indicates Br2, that easily adds to the
double-bond of safrole forming the dibromide and
eventually also brominates in a minior side-reaction
the aromatic ring.

to destroy the Br2 in the homemade HBr/GAA, i suggest
to add some vanillin, that probably under these conditions
will bind the bromine and retransform one half of it
back to the desired HBr:

   vanillin + Br2 --> 5-Br-vanillin + HBr

see also

None

(https://www.thevespiary.org/rhodium/Rhodium/chemistry/mmda.mescaline.html)

there's also a good chance to destroy the bromine simply
with a bit vitamin C (ascorbic acid).  

see

AscorbicAcidTitration

(http://www.cofc.edu/~kinard/221LCHEM/AscorbicAcidTitration.PDF) :

   AscAcid + Br2 --> DehydroAscAcid + 2Br(-) + 2H(+)

but i don't know if ascorbic acid is soluble in HBr/GAA,
and it could also happen that the excess HBr adds to
the double-bond of the ascorbic acid before the Br2 does.
and especially at an elevated temp the HBr could brominate
the OH-groups of the ascorbic acid.
but nevertheless it should be worth a try.

since both suggestions are just theoretical and NOT tested,
i recomend first to make some tests in a test tube.

[Rhodium]

I wouldn't say the above procedures are reccommended at all. The only literature references for removing free bromine from HBr solutions that I have found reccommends the use of red P or H2S.

[endo1]

I appreciate the feedback! Sw was a little more concerned with the freezing problem than with a bit of the dibromo compound forming and he likes to run the reaction very cold. Could Chloroform be added as an "anti freeze" in this case? If so, would it be better to add the chloroform before the solvent is gassed or perhaps to use chloroform by itself as the solvent?

[SirSpicious]

Swiss was looking at halogenating some sassy, but the notion of producing chlorine, bromine, then bubbling HBr(g) through some np solvent seems like alot of effort (HBr looks dificult to come by...) if i had an aqueous solution of 8% HF,8% H₂SO₄, what would be the best way to get our HF chemically acquainted with our sassy? could we just dissolve our sassy in ethanol, add a molar excess of our HF acid and mix well... or will we need a PTC (marriage celebrant??) added to the mix... would DMSO as a solvent require a PTC? and... assuming that it would work.. could i expect greater yields using fluorine (as it's more reactive than iodine & bromine) and lastly... where can i buy teflon coated cargo pants??

-SirSpicious
I'm new! Take everything i say with a pinch of RbCl!

[Rhodium]

You cannot achieve anything useful by hydrofluorinating safrole. Just forget it.

[SirSpicious]

Oh well... swiss really didn't like the thought of doing anything with HF acid... doing some searches popped up a few references to accidents & a fatality of unfortunate people spilling HF on themselves...
thanks for the advice!
-SS
I'm new! Take everything i say with a pinch of RbCl!

[ClearLight]

That systemic calcium binding in the blood stream can be a bitch!
Infinite Radiant Light - THKRA

[Osmium]

I thought we had agreed upon that HBr/AcOH doesn't work?

Post 22772

(Osmium: "Bromosafrole breakthrough?", Serious Chemistry)
I'm not fat just horizontally disproportionate.

[endo1]

I thought we had agreed upon that HBr/AcOH doesn't work?

Apparently, there are still some who disagree:

Post 294894

(hsark: "bromo distillation", Chemistry Discourse), Fester (who gave SW the idea for the above procedure. Here's a clip from Festers book which Ritter apparently likes:

Post 243297

(foxy2: "Re: Notes on bromination of safrole", Methods Discourse),

Post 243301

(Ritter: "Re: Notes on bromination of safrole", Methods Discourse)), Strike and of course SW and his happy bromosafrole to name a few.