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chemoleo
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Would 1,3,5 tribromo (iodo?) benzene be reactive towards thiols, -SH, forming Phe(S-R)3?
I doubt it, as it is on the ring - but confirmation would be appreciated.
PS alkane-Br + HS-R readily reacts to form alkane-S-R and HBr.
Also, cyanogen bromide (Br-CN) forms (when polymerised with acids), cyanuric bromide, which is the triply substituted triazin ring (-C(Br)=N-)3
Would it be possible to condense/polymerise bromo or chloroacetonitrile, Cl-CH2-CN to the bromo/chloro-methyl 1, 3, 5 triazin compound?
The structure would be the same as shown above, except with a methylene (CH2) group between the Cl/Br and ring carbon.
Thoughts?
Never Stop to Begin, and Never Begin to Stop...
Tolerance is good. But not with the intolerant! (Wilhelm Busch)
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crazyboy
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Is a vacuum capable of pulling 21" of Hg good or acceptable for such tasks as vacuum filtration and vacuum distillation or is that too weak?
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Formula409
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Could someone find the solubility of Thiourea Dioxide and d-Camphor in Isopropanol and Toluene pretty please? I'm having no luck.
Formula409.
[Edited on 10-7-2009 by Formula409]
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Nicodem
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No, it can not react with thiols or thioxides unless transition metal catalysed or under extreme conditions.
| Quote: | | PS alkane-Br + HS-R readily reacts to form alkane-S-R and HBr. |
Yes, most primary alkyl bromides will alkylate thiols, even under neutral or only slightly acidic conditions and even at room temperature. The
reaction rate will depend on the pH, solvent medium and alkyl bromide's electrophilicity. Secondary alkyl bromides are much less reactive and tertiary
alkyl bromides mostly succumb to other side reactions since they are unable to undergo SN2 reaction pathways.
| Quote: | Also, cyanogen bromide (Br-CN) forms (when polymerised with acids), cyanuric bromide, which is the triply substituted triazin ring (-C(Br)=N-)3
Would it be possible to condense/polymerise bromo or chloroacetonitrile, Cl-CH2-CN to the bromo/chloro-methyl 1, 3, 5 triazin compound?
The structure would be the same as shown above, except with a methylene (CH2) group between the Cl/Br and ring carbon. |
Cyanuric bromide and chloride are both already quite electrophilic, even much more so than the coresponding 2,4,6-tris(halomethyl)-s-triazine would be
(which due to the electronic effects should be less reactive than benzyl halides).
All nitriles, in principle, can be trimerized, but in practice this is anything but easy (except for cyanogen halides and such). For this reason,
other routes are generally used to prepare s-triazines. For example, 2,4,6-tris(chloromethyl)-s-triazine was prepared from the coresponding alkyl
imidate (Journal of Organic Chemistry, 26 (1961) 2778-2784).
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querjek
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Quote: Originally posted by crazyboy  | | Is a vacuum capable of pulling 21" of Hg good or acceptable for such tasks as vacuum filtration and vacuum distillation or is that too weak?
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It's definitely enough for vacuum filtration.
As for vacuum distillation, 21" corresponds to ~530mmHg. This will lower the boiling point of compounds by roughly 50deg.C. It all depends on whether
or not this is enough for whatever you're looking to distill.
[Edited on 10-7-2009 by querjek]
it's all about chemistry.
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UnintentionalChaos
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On the suggestion of an old thread, I'm considering using two in-line bilge blower fans for a fume hood. Can anyone give me an idea of what kind of
power these have? Am I wasting my time? I was planning on using an absorber column, so there will be some resistance to airflow, but not a lot,
hopefully.
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
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querjek
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Does anybody know where/if I can find phase diagrams of organic compounds?
it's all about chemistry.
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JohnWW
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There are phase diagrams of many
binary and some ternary mixtures of organic compounds in the International Critical Tables (1930), which can be downloaded as a 310 Mb PDF file. Some
such phase diagrams are also give in Chapter 3 of Perry's Chemical Engineers' Handbook, 7th Edition 1997 and 8th Edition 2008; and in the CRC Handbook
Of Chemistry & Physics, of which the 87th, 88th, and (the latest) 89th Editions can be downloaded. Links for downloading these are in appropriate
threads in the References section.
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querjek
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Thank you very much!
Another question:
I've got some spare Anise oil laying around and want to try to refine it a bit.
The composition is said to be mostly:
Phellandrene - b.p. ~172deg.C
terpineol - b.p. ~219deg.C
anethole - b.p. ~234deg.C
If I were to place 20mL of this in an open 100mL beaker and slowly raise the temperature to 175deg.C, do I run the risk of losing the terpiniol and
anethole to the atmosphere?
I know that a full-fledged fractional distillation would be my best bet, but if this would work, I would feel more comfortable not constantly watching
the setup for any temperature spikes.
it's all about chemistry.
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JohnWW
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Raising the temperature of anise oil to just above the boiling point of phellandrene, which is substantially the most volatile major component, would
result in steady loss of that component, as at 172ºC its vapor pressure equals normal atmospheric pressure. There would also be a much slower loss of
the less volatile components at that temperature, having much lesser vapor pressures. To separate and retain these components, as relatively pure
fractions according to their normal boiling points, would require fractional distillation. Preparative-scale gas-liquid chromatography would produce
purer fractions, although still likely to be contaminated with minor components having very similar molecular weights and boiling points to those of
the major components.
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manimal
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I'm trying to find procedures for acetylation of aniline with dilute acetic acid. Two references I have are for Matheson and Co. Eng. Pat. 6220 and
Deutsches Reichspatent 98070. How do I access these patents?
[Edited on 12-7-2009 by manimal]
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Formatik
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Use the european patent office (espacenet) to find your GB and DE patents. Also, because that British patent is way old, enter the full year before
the patent number. Under "number search" enter your country codes before desired patents, e.g. DE98070.
[Edited on 12-7-2009 by Formatik]
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itchyfruit
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COBALT NITRATE
Is cobalt nitrate supposed to be purple ?
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manimal
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I tried "DE98070", but my search was unsuccessful. I'm thinking that there is a special format for entering old patents. Unfortunately, I dont know
the year in which the English patent was published.
The Brit patent no. is GB189706220, if anyone is interested.
[Edited on 12-7-2009 by manimal]
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Formatik
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| Quote: Originally posted by manimal | | I tried "DE98070", but my search was unsuccessful. I'm thinking that there is a special format for entering old patents. Unfortunately, I dont know
the year in which the English patent was published. |
You can use DEPATISnet if you want the old German patents and don't have the year. As to the British patent, no idea how to get it without the year. Maybe
it's referenced somewhere else.
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Polverone
Now celebrating 21 years of madness
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Threads Merged
12-7-2009 at 11:53 |
hissingnoise
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It's a deep red colour on wikipedia. . .
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querjek
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The expected melting point of a compound is 189deg.C. When I tested a sample of mine, it melted around 204deg.C.
I remember something from general chemistry stating that impurities would lower the melting point of a compound (though honestly, that doesn't make
sense to me if the impurities themselves have higher melting points).
Is the previous claim about impurities always true, or could my sample still be ok (by "ok", I mean, "at least could contain some of the compound")?
it's all about chemistry.
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12AX7
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Different amount of moisture maybe?
Can you titrate the amount of anion or cation in the material?
Tim
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merrlin
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| Quote: Originally posted by querjek | The expected melting point of a compound is 189deg.C. When I tested a sample of mine, it melted around 204deg.C.
I remember something from general chemistry stating that impurities would lower the melting point of a compound (though honestly, that doesn't make
sense to me if the impurities themselves have higher melting points).
Is the previous claim about impurities always true, or could my sample still be ok (by "ok", I mean, "at least could contain some of the compound")?
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The addition of impurities may lower or raise the melting point of a substance. The addition of chromium to gold can raise the melting point of gold,
whereas the addition of about 3% silicon to gold will lower the melting point to about 363° C. Search for "eutectic" on Wikipedia and then check out
the the reference link at the bottom of the page:
http://ocw.mit.edu/NR/rdonlyres/Materials-Science-and-Engine...
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manimal
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| Quote: Originally posted by manimal | Since concentrated ammonia solution is so useful but rather scarce, I was thinking that a promising way to prepare it would be to heat intimately
mixed ammonium sulfate and calcium hydroxide in a metal can and pipe the fumes into water.
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I suppose that to judge the concentration, I can measure the volume increase. I am going for 100% increase in volume, because I intend to heat the
CaOH2 and (NH4)2SO4 to a high temperature, and I am taking into account the 2 moles of water released by this reaction (I am heating it that hot to
encourage the reaction to go to completion and to liberate the h2o from the CaSO4, which likes to hold onto it's water).
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entropy51
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Manimal, maybe better to measure the density of your NH3 soln. in H2O. The density of strong ammonia (28%) is about 0.9 gm/mL. Weigh 10 mL to get an
accurate density.
Be sure to cool the water you're absorbing the NH3 in, since absorbtion is exorthermic and NH3 is much more soluble in cold H2O.
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UnintentionalChaos
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| Quote: Originally posted by entropy51 | | Manimal, maybe better to measure the density of your NH3 soln. in H2O. The density of strong ammonia (28%) is about 0.9 gm/mL. Weigh 10 mL to get an
accurate density. |
An appropriate volume depends largely on the capabilities of the scale being used. Hopefully, there are some volumetric flasks around as well.
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
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crazyboy
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What is a reasonable price for a rotovap with and without glassware? I am looking for one and the best I have seen is about $1200  . A little out of my price range but it is in excellent condition w/ glassware.
Any ideas where to get one? Anyone want to get rid of theirs?
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DJF90
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I would say about £500 second hand. Varies by make and model, and there are some bargains out there (under £300 I have seen once), as well as some
overpriced equipment. Obviously this probably depends on location too.
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manimal
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I want to extract paracetamol from pain medication. (I intend to invistigate it's uses as a polymerization inhibitor). This medicine contains
polyethylene glycol, however, which is soluble in water and ethanol. Will the PEG recrystallize w/ the paracetamol after undertaking a water or
ethanol extraction?
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