Sciencemadness Discussion Board

The Most Useful Bromo

Meltonium - 16-2-2017 at 18:29

I am in a bit of a pickle, here. I have some bromine and need to use it for something. The problem is, I can't really think of something to use it for. Well, I can think of things, but I'm not sure if it is worth.

I want to know the most useful organic building block to use bromine for.

If you had the last available bromine left on Earth and had to use it, what would you use it for?

Metacelsus - 16-2-2017 at 18:43

If you want to convert your bromine into something more easily storable, you could make N-bromosuccinimide (of course, this requires succinimide as a starting material). N-bromoacetamide would be easier to make but generally not as useful.

[Edited on 2-17-2017 by Metacelsus]

Magpie - 16-2-2017 at 18:54

You could make acetic anhydride or a Grignard reagent..

Amos - 16-2-2017 at 20:07

Buy some MSG at an Asian market, health store, or grocery. Convert to succinic acid (https://www.youtube.com/watch?v=kDLSRk068SU&t=20s).
Dehydrate with heat to succinic anhydride, add your bromine. Now you can store it indefinitely!

Texium - 16-2-2017 at 22:33

If you have benzene, you could make bromobenzene, using just a bit of aluminum foil to generate the necessary catalyst. Easier to store it, and it can be used for phenyl Grignards. I wouldn't say it's the most useful thing, but it is a useful thing.

The NBS idea is good too. I haven't made it before, but I've used it at work and it is a pleasure to work with.

Boffis - 16-2-2017 at 22:34

@Amos, if you are trying to produce N-bromosuccinimide you have missed out an important step. The introduction of the vital nitrogen of the "imide" group. At a guess I think you would need to heat the ammonium succinate salt.

It also depend on where your interests lie. I would use the bromine to add across the double bond of fumaric or acrylic acid. The resulting dibromo compounds can be dehalogenated to acetylene carboxylic acids with alcoholic KOH. Very useful intermediates... for me at least. :)

[Edited on 17-2-2017 by Boffis]

JJay - 16-2-2017 at 23:21

I'm planning on making some aluminum bromide once the weather warms up and I can do it outside. It's a strong Lewis acid that can be used for Friedel-Crafts alkylations and acylations. The most useful building block you can make with bromine... hmm... good question....

Assured Fish - 17-2-2017 at 00:54

You could possibly try converting it back to its sodium or potassium salt, i had this idea a while back.

3Br2 + 2Al -----> Al2Br6 + 6H2O -----> 2Al(OH)3 + 6HBr
6HBr + 6NaOH -----> 6NaBr

This may seem a little boring but it would mean you could save the bromine for a better project and still do something experimental at the same time.
Id start by putting some aluminium foil in a RB flask with water and stirring and a reflux condenser and then slowly adding the bromine and letting it react until most of the color dissapears, this will take a while because of the aluminium oxide layer but then you could simply add your desired KOH or NaOH solution and filter to remove the Aluminium hydroxide. The bromide salt will remain dissolve in the filtrate and you can evaporate that away to get a dry salt.

PHILOU Zrealone - 17-2-2017 at 03:36

NaOH + Br2 -heat-> NaBr + NaBrO3

I should also work on that because I own two 2L liquid Bromine Glass bottles...and I don't like the idea of it escaping or breaking...

Chlorine - 17-2-2017 at 07:11

Your best option would to convert it to a metal salt, NaBrO3, KBrO3.

Amos - 17-2-2017 at 08:08

Quote: Originally posted by Boffis  
@Amos, if you are trying to produce N-bromosuccinimide you have missed out an important step. The introduction of the vital nitrogen of the "imide" group. At a guess I think you would need to heat the ammonium succinate salt.

[Edited on 17-2-2017 by Boffis]


Ah, woops! It was late at night and I forgot that step. It's actually even easier than that; it can be prepared simply by heating together succinic anhydride and urea, analogous to the preparation of phthalimide.

PHILOU Zrealone - 17-2-2017 at 13:26

Quote: Originally posted by Amos  
Quote: Originally posted by Boffis  
@Amos, if you are trying to produce N-bromosuccinimide you have missed out an important step. The introduction of the vital nitrogen of the "imide" group. At a guess I think you would need to heat the ammonium succinate salt.

[Edited on 17-2-2017 by Boffis]


Ah, woops! It was late at night and I forgot that step. It's actually even easier than that; it can be prepared simply by heating together succinic anhydride and urea, analogous to the preparation of phthalimide.

Should work also via diammonium succinate heating (intermediary formation of amide or diamide) and via heating of a mix of urea succinate (transamidation).

Magpie - 18-2-2017 at 16:16

Quote: Originally posted by Boffis  

It also depend on where your interests lie. I would use the bromine to add across the double bond of fumaric or acrylic acid. The resulting dibromo compounds can be dehalogenated to acetylene carboxylic acids with alcoholic KOH. Very useful intermediates... for me at least. :)

[Edited on 17-2-2017 by Boffis]


Isn't NaNH2 required to get the acetylene bond?

tsathoggua1 - 18-2-2017 at 16:28

I'd go for methyl bromide and a grignard with benzyl cyanide. Ideally creating amphetamine on the hydrolysis of the grignard complex:D

Boffis - 19-2-2017 at 11:08

Quote: Originally posted by Magpie  
Quote: Originally posted by Boffis  

It also depend on where your interests lie. I would use the bromine to add across the double bond of fumaric or acrylic acid. The resulting dibromo compounds can be dehalogenated to acetylene carboxylic acids with alcoholic KOH. Very useful intermediates... for me at least. :)

[Edited on 17-2-2017 by Boffis]


Isn't NaNH2 required to get the acetylene bond?


No. See Org. Synth., Coll Vol 2, p10

PHILOU Zrealone - 19-2-2017 at 15:47

Normally a first halide is substracted at ambiant T° (KOH/Ethanol) and the second needs more forcing conditions (thus slight heating).

Metacelsus - 20-2-2017 at 06:27

Quote: Originally posted by tsathoggua1  
I'd go for methyl bromide and a grignard with benzyl cyanide. Ideally creating amphetamine on the hydrolysis of the grignard complex:D


Depending on your workup, you'd get either the imine or the ketone. Of course, making the amine from either of these would be straightforward.