06-03-02 15:37
No 317157
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
(Newbee)
06-03-02 15:57
No 317159
http://webbook.nist.gov/
.........check here...
(Official Hive Translator)
06-03-02 16:16
No 317161
....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
(Distinctive Doe)
06-03-02 19:24
No 317200
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
(Master Searcher)
06-03-02 19:49
No 317206
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.
The hardest thing to explain is the obvious
(Moderator)
06-03-02 22:08
No 317234
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
(Distinctive Doe)
06-03-02 23:26
No 317245
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
(Moderator)
06-04-02 01:08
No 317278
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
(Master Searcher)
06-04-02 01:36
No 317292
They're not the same compound, lugh.
http://www.geocities.com/dritte123/PSPF.
The hardest thing to explain is the obvious
(Moderator)
06-04-02 01:44
No 317297
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?
(Master Searcher)
06-04-02 02:39
No 317313
hydroxy groups are not the same thing as methoxy groups.
http://www.geocities.com/dritte123/PSPF.
The hardest thing to explain is the obvious
(Moderator)
06-04-02 03:07
No 317321
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)
(Hive Bee)
06-04-02 08:48
No 317421
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 ???)
(Chief Bee)
06-04-02 19:09
No 317551
2,5-Dimethoxybromobenzene (= 2-bromo-1,4-dimethoxybenzene) is a liquid at room temp.
(Official Hive Translator)
06-04-02 19:45
No 317555
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
(Chief Bee)
06-04-02 19:53
No 317560
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.
(Hive Addict)
06-04-02 19:55
No 317561
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?
(Stranger)
06-05-02 02:29
No 317671
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.
(Official Hive Translator)
06-05-02 04:41
No 317706
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 confusedHe 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!
- instead he'll try to chloromethylate it, he thinks.Yours very sincerely,
Antoncho
(Hive Addict)
06-05-02 20:49
No 317897
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.
(Chief Bee)
06-05-02 21:31
No 317906
One article I read suggested the sublimation of 1,4-DMB, followed by vacuum distillation of the dimethoxybromobenzene residue.
(Moderator)
06-05-02 23:33
No 317952
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 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 The point is that it can be confusing using English chemistry publications with alternative naming systems
(Hive Addict)
06-05-02 23:40
No 317954
> product was a black oil...
Probably bromine leftovers :-). Try washing with sodium hydrosulfite, as in PiHKAL #127.