I got curious about the stability of HBr and methods of making it.  I found these patents that look interesting:

1,267,638 discusses NaBr + NaHSO4 --> Na2SO4 + HBr

1,193,552 NaNO3 + H2SO4 --> NaHSO4 + HNO3
          NaCl + NaHSO4 --> HCl +Na2SO4

1,379,731 NaBr + H2SO4 (78%) --> hydrobromic acid

2,705,670 HBr gas from NaBr and dilute H2SO4

3,445,188 HBr produced in organic solvent using NaBr and H2SO4.  One example even uses acetic acid as a solvent.

Compare the last one to US patent 3,864,115 which gives an example (example 1) for making the bromosafrole derivative from safrole and HBr in acetic acid.

I just wanted to nip this urban legend in the bud before anybody gets dissapointed: NaBr and H₂SO₄ do not yield any great amount of bromide gas. Yes, hydrobromic acid is prepared this way, but hydrobromic acid is a solution of hydrogen bromide gas in water - there is a difference here worth noting.

Incidentally, in case you're wondering, the original procedure for preparing hydrobromic acid can be found in Inor. Syn. 1, 155 (1939).

I borrowed this from Rhodium's chemistry page.

http://www.geocities.com/dritte123/PSPF.html

I don't know about the last reactions, iudexk, but anyway, I found some more interesting patents, available on the internet remember.

2307552 discusses Markonikoff mechanism in addition of HX to alkenes, and gasses containing O2 such as air which can form peroxides and the use of antioxidants to promote Markonikoff addition.

5866732 use of aqueous HBr and ZnBr in addition of HBr to alkenes

2058465 antioxidants

3683037 air activation

This thread has a lot of stuff in it relating to bromosafrole and someone's discussing it again (bubbly bubbly).

---

http://www.privacy.org/article.php?sid=620&mode=thread&order=0&thold=0

http://www.privacy.org