Per
Hazard to Others
Posts: 134
Registered: 26-1-2007
Location: Europe
Member Is Offline
Mood: No Mood
|
|
2-bromonaphthalene from naphthalene
I wanted to prepare 2-bromonaphthalene from naphthalene and elemental bromine.
Until now I´ve just found this
http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv5...
route, which doesn´t help me because I´ve no 2-naphthol, triphenylphosphine.
Further I found a synthesis for 1-bromonaphthalene from naphthalene and bromine at 40°C in CCl4, but I need the beta-product.
Römpp mentioned that the beta-position would be preferred substituted at higher temperatures because of isomerism.
Now my idea would be the addition of bromine to molten naphthalene, any chances for success?
Has anybody references about the synthesis of 2-bromonaphthalene from naphthalene and bromine?
|
|
|
Nicodem
Super Moderator
Posts: 4230
Registered: 28-12-2004
Member Is Offline
Mood: No Mood
|
|
| Quote: | Originally posted by Per
Now my idea would be the addition of bromine to molten naphthalene, any chances for success? |
That is a terrible idea! Though I do not know you, I still shiver at the though of what terrible pains, death or disfiguration it would cause you. So
unless you are one of those who firmly believe evolution has to continue by selection based on intelligence, then rather change your idea.
|
|
|
Eclectic
National Hazard
Posts: 899
Registered: 14-11-2004
Member Is Offline
Mood: Obsessive
|
|
What about vapor phase bromination?
Nicodem, please elucidate the hazzards? (Other than the obvious ones of trying to add liquid bromine to molten naphthaline.) 
|
|
|
Per
Hazard to Others
Posts: 134
Registered: 26-1-2007
Location: Europe
Member Is Offline
Mood: No Mood
|
|
Ok, it was just an idea, may not the best.
If I did it, I would had added the bromine just dropwise, better to say the vapors of it.
But by leading bromine vapors at elevated temperaures in naphthaline there would lkely be the problem of several different derivatives.
So I´m still searching for an goog method for the preparation of 2-bromonaphthalene.
|
|
|
Nicodem
Super Moderator
Posts: 4230
Registered: 28-12-2004
Member Is Offline
Mood: No Mood
|
|
I don't think you can obtain 2-bromonaphtalene as a major product from brominating naphthalene. The position 2 is thermodynamically preferred for
electrophiles that react reversibly enough with naphthalene. Br2 is not one of these.
You can use the Sandmeyer reaction on 2-aminonaphthalene (Beware! It is a carcinogen). Preferably not by using mercuric bromide as described in the
reference from the Org. Synth. entry.
|
|
|
Eclectic
National Hazard
Posts: 899
Registered: 14-11-2004
Member Is Offline
Mood: Obsessive
|
|
Isomerization of 1-bromonaphthalene over zeolites?
Google "2-bromo-naphthalene". First item, first page. 
|
|
|
Per
Hazard to Others
Posts: 134
Registered: 26-1-2007
Location: Europe
Member Is Offline
Mood: No Mood
|
|
http://www.freepatentsonline.com/5043493.html
Thanks, I always searched for 2-bromonaphtnalene.
Zeolite, hopefully I´ll find the right one for this application, if I´ll find at least one to buy.
The patent isn´t very detailed, is the 2-isomere prepared by just heating the 1-isomere with a peace of the right zeolite?
|
|
|
not_important
International Hazard
Posts: 3873
Registered: 21-7-2006
Member Is Offline
Mood: No Mood
|
|
| Quote: | Originally posted by Per
http://www.freepatentsonline.com/5043493.html
Thanks, I always searched for 2-bromonaphtnalene.
Zeolite, hopefully I´ll find the right one for this application, if I´ll find at least one to buy.
The patent isn´t very detailed, is the 2-isomere prepared by just heating the 1-isomere with a peace of the right zeolite? |
You'll need more than a single piece of zeolite. The example at the end of the patent uses 20 g 1-Br-naphthalene with 0,5 g granular zeolite, giving
a product containing about 15% of the 2-Br isomer.
|
|
|
Per
Hazard to Others
Posts: 134
Registered: 26-1-2007
Location: Europe
Member Is Offline
Mood: No Mood
|
|
Where did you find the full patent?
I can always just get the little abstract from the link, don´t know what´s getting wrong here.
|
|
|
jam640
Harmless
Posts: 29
Registered: 3-10-2007
Location: Rainbow Island
Member Is Offline
Mood: Fat
|
|
freepatentsonline have a bit confusing website layout. I do not know if you really have a problem or not, but I know that I in the beginning when
following links there thought the same as you just to discover that all you needed to do was to scroll down a page or two to find the full patent
there in plain view. 
|
|
|
Eclectic
National Hazard
Posts: 899
Registered: 14-11-2004
Member Is Offline
Mood: Obsessive
|
|
Use the patent number to access the full downloadable patent here:
European Patent Office
|
|
|
Per
Hazard to Others
Posts: 134
Registered: 26-1-2007
Location: Europe
Member Is Offline
Mood: No Mood
|
|
Now I found the time to read the patent properly and think about it.
The most interesting thing in this patent is it´s introduction.
So if it´s possible to isomerize 1-bromonaphthalene to 2-bromonaphthalene with the common chemical AlCl3, I would try it out.
Conveniently in the liquid phase, unfortunately I haven´t any of the given references.
L. Roux, Bull. Soc. Chim. 45, 510/521 (1886) and J. P. Wibaut et al., Rec. Trav. Chim. 68, 525/546 (1949)
The melting point of the 1-isemere is -1°C, the boiling point 279-281 °C .
The 2-isomere melts at about 50°C and it´s boiling point is similar to the 1-isemere, so they couldn´t seperated by distillation, but the different
melting point´s could be a great help.
I would try it as followed:
1 mole 1-bromonaphthalene are mixed with 1,8 moles AlCl3 (because the patent mentions that much AlCl3 is required) in an Erlenmeyer flask.
Under stirring the mix is heated to about 150° to 200°C for half an hour.
After this the mixture is poured in water to remove the AlCl3, (in the patent is mentioned that salts would be formed, don´t know what they mean)
and cristals of 2-bromonaphthalene should be formed.
Could this work?
|
|
|
Antwain
Hazard to Others
Posts: 252
Registered: 21-7-2007
Location: Australia
Member Is Offline
Mood: Supersaturated
|
|
melting point is no good, as either the meling point of the mix will be in between, or more probably as you heat it up, it will start to melt as a
eutectic below either melting point. Or 1 bromo will dissolve in molten 2-bromo. either way, no dice.
Look for differences in solubility. With such vastly different melting points you may find a good solvent system.
|
|
|
Per
Hazard to Others
Posts: 134
Registered: 26-1-2007
Location: Europe
Member Is Offline
Mood: No Mood
|
|
Differences in solubility are good, if I could find some.
The only physical properties I could find about 2-bromonaphthalene are the melting and the boiling point.
I need it for the preparation of binaphthalene by the magnesium-organyl of 2-bromonaphthalene. Binaphthalene should further give Perylene with AlCl3
as a katalyst in the melting phase.
Binaphthalene is even more curiously than the bromonaphthalene, I could just find lots of derivatives but nearly noething about the main molekul.
It consists of two naphthalene molekules which are bonded in the 2-position.
2-bromonaphthalene + Naphthalene -AlCl3-> Binaphthalene
I don´t know what the 1-Isomere would for in the metal-organic reaction but maybe the isomere-mix could be of enough purity for this reaction.
Has anybody further information about binaphthalene (couldn´t even find the CAS-registry number) or its precursor?
|
|
|
Nicodem
Super Moderator
Posts: 4230
Registered: 28-12-2004
Member Is Offline
Mood: No Mood
|
|
| Quote: | Originally posted by Per
Differences in solubility are good, if I could find some.
The only physical properties I could find about 2-bromonaphthalene are the melting and the boiling point. |
If you read again the mp of the two isomers as you provided them, you would notice they can be cleanly separated by recrystallization, from methanol,
for example.
|
|
|
yan123
Harmless
Posts: 5
Registered: 4-10-2007
Location: china
Member Is Offline
Mood: No Mood
|
|
2-bromomaphthalene is cheap, at least cheaper than 2-aminonaphthalene. maybe it is a good chioce to buy it.
|
|
|
Per
Hazard to Others
Posts: 134
Registered: 26-1-2007
Location: Europe
Member Is Offline
Mood: No Mood
|
|
So if I understood this the two isomers do not build a eutectic solution when they´re solved and the 1-isomere would stay in the solvent during the
2-isomere precipitates out.
@yan123
Yes, 2-bromonaphthalene might be cheap if you could buy it.
I heard that you could buy in china nearly everything you want to, don´t know if it´s true but if so, lucky you.
Might be the heaven for the most hobby chemists.
Here in Germany you can´t easily buy chemicals, all big chemical traders do not deliver private people. Also it´s illegal at all to buy in Germany
poisonous chemicals.
What in china the missing of human rights, may in Germany the useless anti-terror laws, observance and consequences.
By the way a little bit policy.
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
