Antoncho (Official Hive Translator)
06-03-02 15:37
No 317157
      2-Br-1,4-diMeO-B's mp?  Bookmark   

A quick question: could somebee w/an access to appropriate literature provide me with a 2-bromo-1,4-diMeO-benzene's melting point?

Thanx a lot in advance,

Antoncho
 
 
 
 
    java
(Newbee)
06-03-02 15:57
No 317159
      re- mp information  Bookmark   

http://webbook.nist.gov/

.........check here...
 
 
 
 
    Antoncho
(Official Hive Translator)
06-03-02 16:16
No 317161
      Thanx, but....  Bookmark   

....i've already searched every place on the Net i knew of and found nichtfrown - otherwise i wouldn't bee asking.


Anyone else? Please?



Antoncho
 
 
 
 
    foxy2
(Distinctive Doe)
06-03-02 19:24
No 317200
      4-bromo-2,5-dimethoxybenzaldehyde  Bookmark   

Antoncho
I looked a bit but nothing poped out with the answer.
I did find this tho....

mmmm  HCN
Why can't such pretty chemistry use benign reagents??

Preparation of 4-bromo-2,5-dimethoxybenzoic acid.
Bortnik, S. P.; Landau, M. A.; Siryachenko, B. V.; Dubov, S. S.; Yarovenko, N. N.    USSR.   
Zh. Org. Khim.  (1972),  8(2),  340-1.  
Journal  written in Russian.   
Abstract
2,5-(MeO)2C6H3Br reacted with anhyd. HCN in PhCl contg. HCl and AlCl3 to give 75% 4,2,5-Br(MeO)2C6H2CHO (I) after hydrolysis with aq. HCl.  Subsequent oxidn. of I afforded 4,2,5-Br(MeO)2C6H2CO2H, which was also produced in 48% yield by carbonation of 4,2,5-Br(MeO)2C6H2MgBr, prepd. from 4,2,5-Br(MeO)2C6H2Br and Mg in THF.

Those who give up essential liberties for temporary safety deserve neither liberty nor safety
 
 
 
 
    PolytheneSam
(Master Searcher)
06-03-02 19:49
No 317206
      C8H9BrO2  Bookmark   

C8H9BrO2 isn't listed in the formula index in the 60th edition of the Handbook of Chemistry and Physics, but C8H9IO2 is (b651).  b651 is listed under benzene, 1,2-dimethoxy-4-iodo- ; mp is 35 degrees C.  There's no benzene, 1,4-dimethoxy-2-bromo- listed.
Its not in the Merck Index 9th edition, either.

http://www.geocities.com/dritte123/PSPF.html
The hardest thing to explain is the obvious
 
 
 
 
    lugh
(Moderator)
06-03-02 22:08
No 317234
      Bromoquinol  Bookmark   

Bromoquinol, also known as Aldurol, bromohydroquinone and 2-bromo 1,4 dihydroxybenzene crystalizes as leaflets, melts at 110-1 C and sublimes at 113-5 C; soluble in H2O, EtOH, Et2O, C6H6 & AcOH smile Moderately soluble in chloroform and ligroin. Reacts with ferric chloride to form bromo-pbenzoquinone smile
 
 
 
 
    foxy2
(Distinctive Doe)
06-03-02 23:26
No 317245
      confused  Bookmark   

lugh
What are those properties of?
bromohydroquinone or 2-bromo 1,4 dimethoxybenzene?

Those who give up essential liberties for temporary safety deserve neither liberty nor safety
 
 
 
 
    lugh
(Moderator)
06-04-02 01:08
No 317278
      Nomenclature  Bookmark   

They are alternate names for the same compound, remember there are four different chemical naming systems in English, as opposed to German, which has only one system of chemical nomenclature smile
 
 
 
 
    PolytheneSam
(Master Searcher)
06-04-02 01:36
No 317292
      They're not the same compound, lugh.  Bookmark   

They're not the same compound, lugh.

http://www.geocities.com/dritte123/PSPF.html
The hardest thing to explain is the obvious
 
 
 
 
    lugh
(Moderator)
06-04-02 01:44
No 317297
      Oxford Press's Dictionary of Organic Compounds  Bookmark   

I'm quoting Oxford Press's Dictionary of Organic Compounds, the entry is under Bromoquinol smile The OH groups are para or 1,4 positions on the benzene ring, thus the bromo group is always in the 2 position. What source do you have that disputes Oxford?
 
 
 
 
    PolytheneSam
(Master Searcher)
06-04-02 02:39
No 317313
      hydroxy groups are not the same thing as methoxy ...  Bookmark   

hydroxy groups are not the same thing as methoxy groups.

http://www.geocities.com/dritte123/PSPF.html
The hardest thing to explain is the obvious
 
 
 
 
    lugh
(Moderator)
06-04-02 03:07
No 317321
      Ether  Bookmark   

Instead of calling the CH2O groups methoxy groups, Oxford's uses the Di-Me ether terminology, but no melting point is given frown It does list a boiling point of 262-3 C, insoluble in water and soluble in most organic solvents. Density is listed as 1.445, further information may be able to be found in the listed references, Am Chem J 42 491 (1909); Chem Zentr II, 2451 (1932) & Ann 209 105 (1881) smile
 
 
 
 
    Mountain_Girl
(Hive Bee)
06-04-02 08:48
No 317421
      Some more info  Bookmark   

2-bromo-1,4-dimethoxybenzene = 1-bromo-2,5-dimethoxybenzene
CAS 25245-34-5
bp = 260-262C @ 760 mm Hg, 131C @ 10 mm Hg
Unfortunately no mp found.
However the related compound, 1-bromo-2,4-dimethoxybenzene has an mp of 25-26C, so I would guess that 2-bromo-1,4-dimethoxybenzene would have a higher mp than this (maybe somewhere around 80C ???)
 
 
 
 
    Rhodium
(Chief Bee)
06-04-02 19:09
No 317551
      Low melting point  Bookmark   

2,5-Dimethoxybromobenzene (= 2-bromo-1,4-dimethoxybenzene) is a liquid at room temp.
 
 
 
 
    Antoncho
(Official Hive Translator)
06-04-02 19:45
No 317555
      Pheeeeewwwww...  Bookmark   

Rhodium, you wouldn't believe how glad i am to hear that!

Means SWIM hasn't totally fucked everything up after allsmile

Do you by chance know if it steam-distills? Or any other means of purification, xcept for vac-distillation?

smile thanx a lot,



Antoncho
 
 
 
 
    Rhodium
(Chief Bee)
06-04-02 19:53
No 317560
      Mountain Girl lists an atmospheric boiling point ...  Bookmark   

Mountain Girl lists an atmospheric boiling point above, so it is probably stable enough to distill without vacuum. I'd suspect it would be too much of a hassle to steam distill it, considering its high boiling point.
 
 
 
 
    yellium
(Hive Addict)
06-04-02 19:55
No 317561
      Heh. You should have asked the question `is ...  Bookmark   

Heh. You should have asked the question `is 2-Br-1,4dmb a liquid at RT?'.

The 2-bromo-1,4-dimethoxybenzene SWIM saw had a slightly greenish tinge, and did not freeze at -18. IIRC. Cooling can result in the deposition of dissolved 1,4-dimethoxybenzene, so that can be used as a `last effort' to clean things up, if quantities are too small for distilling, and kugelrohr's are out of the question.
It also has a very typical smell. Not as annoyingly sweet as 1,4-DMB, but more lubricant-alike.

What's the next thing you're going to do with it? Grignard?
 
 
 
 
    anton_berg
(Stranger)
06-05-02 02:29
No 317671
      2-bromodimethoxybenzene vs. 2-bromohydroquinone  Bookmark   


I'm quoting Oxford Press's Dictionary of Organic Compounds, the entry is under Bromoquinol  The OH groups are para or 1,4 positions on the benzene ring, thus the bromo group is always in the 2 position. What source do you have that disputes Oxford?




Um, I don't think anybody has a problem with Oxford's dictionary, but bromoquinone and bromodimethoxybenzene are most certainly not the same compound. Period. Quinones have two hydroxy functional groups on their rings, but dimethoxybenzene has... you guessed it: two methoxy groups. One has a the empirical forluma C6H5BrO2 (bromoquinol, as you call it), while the other has the formula C8H9BrO2.

BTW, forgive my ignorance, but what are these four systems of English nomenclature, and who developed them? Every system of word-based nomenclature I've ever encountered seemed inherently German in structure. I can't think of any fundamental nomenclature practices that weren't first developed by German chemists, and then later adopted by the rest of the world.

 
 
 
 
    Antoncho
(Official Hive Translator)
06-05-02 04:41
No 317706
      2-bromo-DMB  Bookmark   

Dear Yellium!

It was even nicer to read your post than the previous one by Rh!smile

The picture SWIM got after brominating p-DMB w/dioxane dibromide (NOT KBr3blush - unfortunately, that proc. was found after the rxn was done) was a black oil w/a smell very similar to what you describe. That oil somewhat solidified in the freezer, but  immediately melted again when brought to the ambience. Naturally, judging from mp xtrapolations, SWIM was very confusedsmile

He thinks he'll try (not very soon tho) to 1st steam-distill out the leftover p-DMB and then pull out the product with overheated steam....... Could get it to work, w/a minimal amt of luckwink

As for the intended usage - SWIM's qualification is far far beehind the level of making Grignars, esp. phenylic!laugh - instead he'll try to chloromethylate it, he thinks.


Yours very sincerely,

Antoncho
 
 
 
 
    yellium
(Hive Addict)
06-05-02 20:49
No 317897
      Distilling anything with a sizeable fraction of ...  Bookmark   

Distilling anything with a sizeable fraction of 1,4-DMB in it is a bitch. The 1,4-DMB will nicely distill, and then solidify on your cooler, either clogging up your vacuum, or making it separation nearly impossible, because when the next (liquid) fraction comes over, it dissolves all the 1,4-DMB again. Definately kugelrohr stuff.
 
 
 
 
    Rhodium
(Chief Bee)
06-05-02 21:31
No 317906
      One article I read suggested the sublimation of ...  Bookmark   

One article I read suggested the sublimation of 1,4-DMB, followed by vacuum distillation of the dimethoxybromobenzene residue.
 
 
 
 
    lugh
(Moderator)
06-05-02 23:33
No 317952
      Remedy  Bookmark   


BTW, forgive my ignorance, but what are these four systems of English nomenclature, and who developed them? Every system of word-based nomenclature I've ever encountered seemed inherently German in structure. I can't think of any fundamental nomenclature practices that weren't first developed by German chemists, and then later adopted by the rest of the world.




The best remedy for ignorance is a trip to the library, fresh air is a good thing laugh If one were to do this, one might find out that at one time there was a traditional terminology used by organic chemists in the English speaking world, then the Royal Chemical Society devised a scheme of nomenclature (as seen in the Dictionary of Organic Compounds); not to be outdone by the English, the American Chemical Society devised their own system of nomenclature (as seen in Chemical Abstracts); and in 1957 the International Union of Pure and Applied Chemistry decided to end this conflict with their system, which is the standard now smile The purpose of this forum is chemistry, not history, so there's no reason to discuss again the primal nature of German Organic Chemistry, or for that matter, the fact that English is partially derived from Old German laugh The point is that it can be confusing using English chemistry publications with alternative naming systems laugh

 
 
 
 
    yellium
(Hive Addict)
06-05-02 23:40
No 317954
      > product was a black oil...  Bookmark   

> product was a black oil...

Probably bromine leftovers :-). Try washing with sodium hydrosulfite, as in PiHKAL #127.