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Author: Subject: The short questions thread (1)
Sedit
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[*] posted on 18-1-2009 at 11:32


That was perfect Not_important thanks:D
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Klute
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[*] posted on 18-1-2009 at 12:51


appetsbud,

I have prepared paraformaldehdye from 37% formalin several times, by just vacuum distilling the solution until water distillate slowls down consoderably, and cooling the resulting thick limpid syrup, which slowly sets to waxy paraformaldehyde. tricky to get out of the flask at first, it cna be worth directly pouring it hot on a cool thick pyrex dish, and "crushing" it with a spatula tot acheive the granulometry you want. Once cold, it is very hard to further "grind" or cut up.

I finished by drying it over NaOh or P2O5 to get a very hard white material, which cna then be powdered with a pestle and mortar, but this isn't practical and it flies everywhere..

here is a picture of the produced paraformaldehdye:





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[*] posted on 20-1-2009 at 07:35


Apparently my question was missed, so I'm gonna post it again:

Quote:
Alright, I will have to ask something after all. I am far away from my Merck Index, so could someone be so kind as to post the whole Merck Index entry for the antihyperlipidemic acipimox? I am especially looking for synthesis-related references.


I can't use my Merck Index on a Linux machine :( so could someone be so kind?

sparky (~_~)




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smuv
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[*] posted on 20-1-2009 at 19:17
Acipimox; Merck Index 14th Edition


Monograph Number: 0000111
Title: Acipimox
CAS Registry Number: 51037-30-0
CAS Name: 5-Methylpyrazinecarboxylic acid 4-oxide
Additional Names: 2-carboxy-5-methylpyrazine 4-oxide
Manufacturers' Codes: K-9321
Trademarks: Olbemox (Pharmacia); Olbetam (Pharmacia)
Molecular Formula: C6H6N2O3
Molecular Weight: 154.12
Percent Composition: C 46.76%, H 3.92%, N 18.18%, O 31.14%
Literature References: Prepn: V. Ambrogi et al., DE 2319834; eidem, US 4002750 (1973, 1977 both to Carlo Erba). Prepn and toxicology: eidem, Eur. J. Med. Chem. 15, 157 (1980). Pharmacological profile: P. P. Lovisolo et al., Pharmacol. Res. Commun. 13, 151, 163 (1981). Pharmacokinetics: L. M. Fuccella et al., Clin. Pharmacol. Ther. 28, 790 (1980); L. Musatti et al., J. Int. Med. Res. 9, 381 (1981). Mechanism of action: K. Aktories et al., Arzneim.-Forsch. 33, 1525 (1983).
Properties: Crystals from water, mp 177-180°. LD50 orally in mice: 3500 mg/kg (Ambrogi).
Melting point: mp 177-180°
Toxicity data: LD50 orally in mice: 3500 mg/kg (Ambrogi)
Therap-Cat: Antilipemic.
Keywords: Antilipemic; Nicotinic Acid Derivatives.




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Sauron
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[*] posted on 20-1-2009 at 21:48


Recently someone posted about a chemical-equation writing utility software or applet,

I have tried UTFSE without avail.

Can some one point me to the proper place?




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[*] posted on 21-1-2009 at 00:37


Sauron, do you mean for drawing out organic reactions? I personally use this freeware: http://www.acdlabs.com/download/chemsk.html



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Sauron
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[*] posted on 21-1-2009 at 01:47


No, not a 2D structure drawing app. I use MDL ISISDraw for that.

This is something that automatically handles chemical EQUATIONS:

NaOH + HCl -> NaCl + H20

It puts these in bold and subscripts the numbers automatically

Apparently it is a TSR applet.




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[*] posted on 21-1-2009 at 13:02


I am currently stuck on a question I have come up with. If I were to dehydrate ethanol to ethene using conc. sulphuric acid then what kind of elimination would this be (E1/E2)?

I dont think it would be E1 because the primary carbocation isn't stable enough, and I dont think E2 can occur because that only happens in basic conditions (and we need the acid so that the hydroxyl group becomes a good leaving group; water). The only base that could be present is the HSO4- ion, which I understand works for the case of t-BuOH (its a poor base but an even worse nucleophile), but I E2 needs a strong base to deprotonate a carbon atom.

After attempting a google search I have come across pages saying the mechaism is E2 (ie. via the carbocation) but these are GCSE help guides and I dont think that the carbocation is stable enough to be formed.
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[*] posted on 21-1-2009 at 14:32


Well, you have to take into account that your concentrated sulfuric acid actually transforms your ethanol first into ethyl hydrogen sulfate, CH<sub>3</sub>CH<sub>2</sub>-O-SO<sub>2</sub>-OH . So your idea of transforming the -OH group into a better leaving group is correct.

sparky (~_~)




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[*] posted on 21-1-2009 at 14:56


Right, you got a mechanism for the production of the bisulphate ester? I tried to draw it starting with nucleophilic attack of the acid by the alcohol (like in a fischer esterification) and I had little luck creating a mechanism that seemed likely. From the bisulphite I assume E2 elimination to occur, with a H being removed off of the methyl group causing creation of the double bond and departure of the bisulphate ion? What is the base that removes the proton?

Is this the reaction mechanism solely because its a primary alcohol (the sterics of a sec/tert alcohol prevent ester formation?)? I know elimination from t-BuOH isn't via the bisulphate ester because protonation of OH allows it to leave as water and create a carbocation, which then is deprotonated by the bisulphite ion thus producing isobutene.

[Edited on 21-1-2009 by DJF90]
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[*] posted on 21-1-2009 at 22:16


Is it possible to dehydrate Aluminium Chloride Hexahydrate by resubliming it?
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[*] posted on 21-1-2009 at 22:34


Maybe I should move my post to the Short Unanswered Questions thread?



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[*] posted on 22-1-2009 at 00:06


Not something I've seen Sauron. Although it would be a really useful app, especially when you have to write a document with 10^n equations in it.
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[*] posted on 22-1-2009 at 00:10


Quote:
Originally posted by raiden
Is it possible to dehydrate Aluminium Chloride Hexahydrate by resubliming it?


No, you can't even just plain sublime it; it loses HCl to form basic chlorides and then Al(OH)3, Al(O)OH, and Al2O3 as heating is continued.
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[*] posted on 22-1-2009 at 01:40


I saw this on the forum just 3-4 days ago and it appeared to be a fresh post. But I have tried and tried to find it via FSE and nothing turns up.

I search on

writing chemical equations
chemical equation writing
equation writing
writing equations
and each of those appended by "software" or "program"

No results.




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[*] posted on 22-1-2009 at 09:23


http://www.sciencemadness.org/talk/viewthread.php?tid=4268&a...

Post by ayush, 31-12-2008 at 19:16,

Quote:

This multifunctional periodic table is an excellent tool for both students and serious researchers. It has over 20 types of data on each element and all known isotopes in customizable, user-expandable tables. All sixteen numeric data types (plus any user-added data) can be corelated in particle or line graphs. Includes a powerful chemical equation balancer that can solve the most complex organic reactions and calculate molecular weights and amounts of reagents.


Not exactly what you describe but along the right lines?
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[*] posted on 22-1-2009 at 12:07


Sorry, nope, that's not it.



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[*] posted on 22-1-2009 at 18:26


This may have been answered before, but it's been nagging at me today so I figured I'd ask. How are superconducting magnets, like those in NMR machines, magnetized? Once they're cooled to a superconducting temperature, is an external magnetic field applied to induce current flow, or is it induced by some sort of cryogenic voodoo magic?



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[*] posted on 22-1-2009 at 20:27


They are DC electromagnets - http://en.wikipedia.org/wiki/Superconducting_magnet#Operatio...
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[*] posted on 25-1-2009 at 00:31


Sauron, I don't know if this is exactly what you mean, but it will balance equations and has some other nice features. I use it quite a bit.
http://home.c2i.net/astandne/help_htm/dwnload1.htm

Oh, I found it, here near the top: https://sciencemadness.org/talk/viewthread.php?tid=4268&...



Now for a question of mine: Can you make nitrite esters of long chain alkanols like dodecanol or cetyl alcohol the same way you make nitrites like isopropyl nitrite, NaNO2 + HCl? I wonder how well it would work because they're not soluble in water... Maybe with the addition of another solvent to increase their solubility?

After looking around some more I've found that lauryl alcohol is like 0.0003% soluble in plain water, but when there is some sodium lauryl sulfate present, its solubility is greatly increased, up to maybe 1 or 2%, which should be plenty for it to react, considering that is how soluble amyl alcohol is, and it is known to work with the one-pot NaNO2 + acid route.. Here's the ref. The lauryl sulfate should be stable in the conditions right? Hopefully the foaming doesn't become too problematic... fatty alcohols are used specifically as defoamers after all..

[Edited on 25-1-2009 by 497]
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[*] posted on 25-1-2009 at 11:19


Does Hydrogen have a disassociation frequency such as chlorine does?
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[*] posted on 26-1-2009 at 16:08


What the F**K has been up these past 24hrs or so? Sciencemadness had been down, files deleted from server or something?! I felt like a junkie without smack! Totally distraught and lost amongst the sea of Roguesci! Thank god this is back up now!



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[*] posted on 26-1-2009 at 17:47


Quote:
Originally posted by Sedit
Does Hydrogen have a disassociation frequency such as chlorine does?


Yes, way down in the deep ultraviolet, disassociation happening at 840 A or shorter.

http://www.nature.com/nature/journal/v118/n2973/abs/118592c0...
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[*] posted on 26-1-2009 at 19:02


Thank you.
Once this was accomplished would this cause the hydrogen to behave as it does in the presents of catylist and be useful for hydronation efforts?
A radical hydrogen seems like it could be very useful if it could be produced from the use of light in a reaction vessle.
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[*] posted on 26-1-2009 at 22:20


This - 840 A, the absorption starts at about 1200 A IIRC - is in the extreme or vacuum UV, although a pure nitrogen atmosphere is transparent in the range. It's not easy to generate much light in this range, and the photons carry a lot of energy - above 10 eV. I suspect that you'd find that most organics fragment under the required conditions.
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