Author Topic: 2-Br-1,4-diMeO-B's mp?  (Read 2297 times)

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Antoncho

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2-Br-1,4-diMeO-B's mp?
« on: June 03, 2002, 03:37:00 PM »
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

  • Guest
re- mp information
« Reply #1 on: June 03, 2002, 03:57:00 PM »

http://webbook.nist.gov/



.........check here...

Antoncho

  • Guest
Thanx, but....
« Reply #2 on: June 03, 2002, 04:16:00 PM »
....i've already searched every place on the Net i knew of and found nicht :(  - otherwise i wouldn't bee asking.


Anyone else? Please?



Antoncho

foxy2

  • Guest
4-bromo-2,5-dimethoxybenzaldehyde
« Reply #3 on: June 03, 2002, 07:24:00 PM »
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.

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PolytheneSam

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C8H9BrO2
« Reply #4 on: June 03, 2002, 07:49:00 PM »
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.

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The hardest thing to explain is the obvious

lugh

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Bromoquinol
« Reply #5 on: June 03, 2002, 10:08:00 PM »
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  :)  Moderately soluble in chloroform and ligroin. Reacts with ferric chloride to form bromo-pbenzoquinone  :)

foxy2

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confused
« Reply #6 on: June 03, 2002, 11:26:00 PM »
lugh
What are those properties of?
bromohydroquinone or 2-bromo 1,4 dimethoxybenzene?

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lugh

  • Guest
Nomenclature
« Reply #7 on: June 04, 2002, 01:08:00 AM »
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  :)

PolytheneSam

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They're not the same compound, lugh.
« Reply #8 on: June 04, 2002, 01:36:00 AM »
They're not the same compound, lugh.

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lugh

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Oxford Press's Dictionary of Organic Compounds
« Reply #9 on: June 04, 2002, 01:44:00 AM »
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?

PolytheneSam

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hydroxy groups are not the same thing as methoxy ...
« Reply #10 on: June 04, 2002, 02:39:00 AM »
hydroxy groups are not the same thing as methoxy groups.

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lugh

  • Guest
Ether
« Reply #11 on: June 04, 2002, 03:07:00 AM »
Instead of calling the CH2O groups methoxy groups, Oxford's uses the Di-Me ether terminology, but no melting point is given  :(  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)  :)

Mountain_Girl

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Some more info
« Reply #12 on: June 04, 2002, 08:48:00 AM »
2-bromo-1,4-dimethoxybenzene = 1-bromo-2,5-dimethoxybenzene
CAS 25245-34-5
bp = 260-262°C @ 760 mm Hg, 131°C @ 10 mm Hg
Unfortunately no mp found.
However the related compound, 1-bromo-2,4-dimethoxybenzene has an mp of 25-26°C, so I would guess that 2-bromo-1,4-dimethoxybenzene would have a higher mp than this (maybe somewhere around 80°C ???)

Rhodium

  • Guest
Low melting point
« Reply #13 on: June 04, 2002, 07:09:00 PM »
2,5-Dimethoxybromobenzene (= 2-bromo-1,4-dimethoxybenzene) is a liquid at room temp.

Antoncho

  • Guest
Pheeeeewwwww...
« Reply #14 on: June 04, 2002, 07:45:00 PM »
Rhodium, you wouldn't believe how glad i am to hear that!

Means SWIM hasn't totally fucked everything up after all :)

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

:)  thanx a lot,



Antoncho

Rhodium

  • Guest
Mountain Girl lists an atmospheric boiling point ...
« Reply #15 on: June 04, 2002, 07:53:00 PM »
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

  • Guest
Heh. You should have asked the question `is ...
« Reply #16 on: June 04, 2002, 07:55:00 PM »
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

  • Guest
2-bromodimethoxybenzene vs. 2-bromohydroquinone
« Reply #17 on: June 05, 2002, 02:29:00 AM »

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

  • Guest
2-bromo-DMB
« Reply #18 on: June 05, 2002, 04:41:00 AM »
Dear Yellium!

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

The picture SWIM got after brominating p-DMB w/dioxane dibromide (NOT KBr3 :-[  - 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 confused :)

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 luck ;)

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


Yours very sincerely,

Antoncho

yellium

  • Guest
Distilling anything with a sizeable fraction of ...
« Reply #19 on: June 05, 2002, 08:49:00 PM »
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

  • Guest
One article I read suggested the sublimation of ...
« Reply #20 on: June 05, 2002, 09:31:00 PM »
One article I read suggested the sublimation of 1,4-DMB, followed by vacuum distillation of the dimethoxybromobenzene residue.

lugh

  • Guest
Remedy
« Reply #21 on: June 05, 2002, 11:33:00 PM »

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  ;D  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  :)  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  ;D  The point is that it can be confusing using English chemistry publications with alternative naming systems  ;D


yellium

  • Guest
> product was a black oil...
« Reply #22 on: June 05, 2002, 11:40:00 PM »
> product was a black oil...

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