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Author: Subject: The short questions thread (3)
gsd
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[*] posted on 13-2-2011 at 16:07


Quote: Originally posted by Sedit  
I have found Platinum powder in an art shop. Its not much but I wanted to get some thoughts on if its ok to use for some reactions or not. Its only .4 grams for about $4 or something like that ..............

What do ya'll think. Would it be of any use?


The current price of platinum metal is about $1850/oz i.e. roughly $65/gm.

So if nothing else, not a bad investment :)

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[*] posted on 13-2-2011 at 19:50


That cant be right then can it? Im going to have to look at that again. Maybe its .04oz that would make more sense.




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[*] posted on 14-2-2011 at 11:52


@ Sedit - Unlikely, note that .04oz is even more (over a gram)!
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[*] posted on 14-2-2011 at 11:58


Lol yeh my fault I ment .04 grams.




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[*] posted on 14-2-2011 at 16:08


I was reading this: http://lambdasyn.org/synfiles/bromovanillin.htm

I noticed in the first example, using KBr in GAA/water/H2SO4 that the KBr is 2eq to vanillin used. Would this not dibrominate the vanillin? Or is it based on available bromine or something, I'm having trouble figuring it out.
If this was subbed with NaBr could it too be used in 2eq to vanillin producing the wanted product?
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[*] posted on 16-2-2011 at 13:34


Could anyone explain what these are:

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=110...

They're definitely stillheads, because they have two male joints and anyway basically look the same as splash stillheads. But what are the other bits for? The tube coming off of the side looks like a vacuum outlet, but surely this should be on the receiver? And what about the tube coming down from the bottom, what's that supposed to do?
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[*] posted on 16-2-2011 at 19:34


Steam distiallation heads. The side tube is attached to steam source, which leads down to into the flask. The vapour then passes through the splash head, and to the condenser that you'll have to attach.
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[*] posted on 16-2-2011 at 22:32


Quote: Originally posted by Mossydie  
Could anyone explain what these are:

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=110...

They're definitely stillheads, because they have two male joints and anyway basically look the same as splash stillheads. But what are the other bits for? The tube coming off of the side looks like a vacuum outlet, but surely this should be on the receiver? And what about the tube coming down from the bottom, what's that supposed to do?


Looks like equipment for kjeldahl nitrogen determinations to me. The tube might be for air flow to carry the last of ammonia into the reciever. I'm just guessing though.




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[*] posted on 16-2-2011 at 23:23


Don't believe me then... http://www.scilabware.com/Adapters/Steam-distillation-head/p...
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[*] posted on 17-2-2011 at 11:10


Thanks for the help
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[*] posted on 18-2-2011 at 18:15


Hello all,

I just have a couple quick questions firstly, I have some cation exchange resin in the H+ form and i was wondering if anyone knows how I may determine the resins exchange potential per/cm3? The resin type is Amberlite IRN-77.

Secondly, would someone out ther is S.M land reccomend a good book that encompasses the theory and thus applications of the various exchange media? thanks in advance for any help.
SHADY..
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[*] posted on 19-2-2011 at 14:51


Does anyone have any ideas?
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[*] posted on 23-2-2011 at 02:01


I read that if I react phtalic acid and phenol i get phenolphtalein. What would happen if I would react phenol with terephtalic acid, would I get phenolphtalein or maybe phenolterephtalein exists? WOuld phenolterephtalein also work as indicator?
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[*] posted on 23-2-2011 at 20:06


Quote: Originally posted by Random  
I read that if I react phtalic acid and phenol i get phenolphtalein. What would happen if I would react phenol with terephtalic acid, would I get phenolphtalein or maybe phenolterephtalein exists? WOuld phenolterephtalein also work as indicator?


You need to use phthalic anhydride, not phthalic acid. The reaction is a friedel crafts acylation followed by a second condensation to yield a tertiary alcohol that cyclizes to a lactone The indicator's ability to change colors relies on the ortho carboxylate group.

Phthalic acid is cheap and decent conversion to the anhydride can be had by simple heating.

To be fair, I ran a very small scale version using sulfuric acid, phenol, and phthalic acid. Enough was formed that I could get very intense color changes with the diluted reaction mixture, but not enough to isolate any product

EDIT: might as well add a question of my own. I remember something about selective sulfonation of mixed xylenes to seperate the isomers, but my search-fu seems to be weak tonight. Does anyone have this reference?

[Edited on 2-24-11 by UnintentionalChaos]




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[*] posted on 28-2-2011 at 08:42


Does anyone know if Platinum plated electrodes could be used in a Kolbe electrolysis, I have yet to find someone local to sell me a small amount of Pt wire but I did manage to get ahold of some plated wire with a coating 2 microns think.

BTW: That other Platinum powder I spoke of earlier in this thread was a bust. I checked it out and on the back it clearly states it contains Copper so I highly doubt there is much Pt if any in that powder at all. That would explain the .4oz of Platinum powder for $5.





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[*] posted on 1-3-2011 at 10:52


Is there a way to test for water in methanol? I sometimes buy 5 gallon amounts from a speed shop/racing store and I got the last of a 55 gallon drum. It was very hot and humid that day and I have to wonder how much water the methanol absorbs every time they pump some out. It didn't seem to burn as well as before. Even with just a little water in methanol, it can affect how some engines/devices run. I'm talking about less than 5% water.
I use methanol a lot, and sometimes for small experiments I will buy some HEET just to make sure the methanol hasn't absorbed water from the air.
Or is there an easy way to dehydrate it completely without doing some methoxide reaction?
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[*] posted on 1-3-2011 at 11:10


Anhydrous copper sulfate? Alcohols are usually dehydrated with CaO or K<sub>2</sub>CO<sub>3</sub>.
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[*] posted on 1-3-2011 at 11:17


Quote: Originally posted by Morgan  
Is there a way to test for water in methanol?

You can do a Karl-Fischer titration to get an exact measurment, but that requires buying the required solution (Hydranal). If you need just a rough qualitative test you can add your methanol dropwise into some toluene. If there is much water inside you will get some turbidity instead of a clear solution (the turbidity will disappear once you add enough methanol). I guess you could actually make this a primitive quantitative test if you make a calibration curve with methanol solutions of known water content. However, it will not show anything if your methanol only has little moisture, though you could greatly enhance the sensitivity by using hexane/toluene mixtures instead (white spirit or any other OTC source of alkanes will do instead of hexane, but some toluene must be present because methanol is not fully miscible in alkanes).
Another primitive test using only OTC materials is adding some anhydrous CuSO4 to methanol and letting it stay over night. If there is some water present, the salt will partially colourize blue. Anhydrous white CuSO4 can be made by heating CuSO4.5H2O.




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[*] posted on 1-3-2011 at 14:33


Thanks, maybe I will try the copper sulfate. I once made some anhydrous CuSO4 , it's funny how it doesn't suddenly reuptake the water previously driven off.
The toluene turbidity test seems good too. Has anyone heard of using cornstarch to absorb water or what percentage it would take out.
The other day I tried a few crystals of KMNO4/purple salt, but it was old in a moist environment and I didn't even know if it was soluble in methanol. if it would be worth a try to detect water.
Another thing, I once dehydrated some magnesium sulfate just to see how it would burn with powdered magnesium and it burns fine, but I can't recall, but it seems like it too was slow to rehydrate.

[Edited on 2-3-2011 by Morgan]
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[*] posted on 2-3-2011 at 21:41


Does anyone know if PdCl2 on carbon will work in a catalytic transfer hydrogenation? According to Orgsyn you can toss it directly into a standard H2 gas hydrogenation as long as a little HCl won't hurt, but I'm not convinced it would work the same for a CTH. I couldn't find any word online about it. Thanks.
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[*] posted on 6-3-2011 at 10:21


With methanol a platinum catalyst will produce some formadehyde. What will platinum catalysts produce when reacted with isopropyl alcohol? And with ethanol is it just acetyldehyde? Or are there other byproducts?
I recall Dobereiner made a vinegar producing lamp using platinum and ethanol(?) somehow.



[Edited on 6-3-2011 by Morgan]
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[*] posted on 6-3-2011 at 18:57


The reason I asked is I saw this video of a catalytic lamp that runs on isopropyl alcohol and platinum.
http://www.youtube.com/watch?v=oiPwzYsldfk

"What is Ashleigh & Burwood Lamp Fragrance made from?"
"The basis of the Lamp Fragrance, and the important fuel which keeps the catalytic process working, is an alcohol called isopropyl alcohol. A very common alcohol, it is the same form of alcohol which is commonly used in hospital anti-bacterial handwashes for example. The other ingredients are distilled water, and the fragrance compound itself."
http://www.ashleigh-burwood.co.uk/lamps-faq.html

"I find the fragrance too strong, what can I do?"
"Firstly, be sure that you are not using the lamp for extended periods of time, especially in smaller rooms and when the door(s) and window(s) are closed. Fragrance Lamps are incredibly effective at fragrancing the air (unlike a room spray for example where the fragrance droplets will fall to the ground after a few minutes) and you will find that the fragrance lingers for several hours in the room after the lamp has been stopped. If you feel that it is the fragrance itself which is too strong for your liking, then it is possible to dilute down one of our Lamp Fragrances, using the Neutral (unfragranced) variety – this is product code PFL900 for the 250ml bottle, and PFL928 for the 500ml bottle. You can mix in any ratio you like until you find the level which best suits you."
http://www.youtube.com/watch?v=i4644kytStI&feature=relat...




[Edited on 7-3-2011 by Morgan]
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[*] posted on 7-3-2011 at 07:55


I wonder what the adhesive coating technique was?
"The filter paper wrapping of 1823 was succeeded
by a dried and ignited mixture of platinum
sponge and potters’ clay; and an improved
version of the Dobereiner lamp had its
platinum sponge applied in an adhesive
coating on a coil of platinum wire."
http://www.platinummetalsreview.com/pdf/pmr-v9-i4-136-139.pd...
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[*] posted on 7-3-2011 at 08:16


Here's the tidbit I sited about making acetic acid from ethanol. Still I wonder what isopropyl alcohol makes when reacted with platinum?
"In 1821, after reading Edmund Davy’s article
in a German translation which appeared in that
year, Döbereiner repeated this experiment and
found that the ethanol was oxidised to acetic
acid. Because the platinum was not consumed,
he suggested that the reaction could be used
“for the large-scale preparation of acetic acid”
(Essigsäure) (27), and he even designed a vinegar
lamp (Essiglampe), in which ethanol was supplied
by a cotton wick to a small funnel containing
platinum black."
http://docserver.ingentaconnect.com/deliver/connect/matthey/...

[Edited on 7-3-2011 by Morgan]
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[*] posted on 7-3-2011 at 11:02


This is a picture with some 91% isopropyl alcohol reacting with my platinum gauze. I couldn't tell by the smell what the products of combustion might be.



[Edited on 7-3-2011 by Morgan]

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