| Pages:
1
2 |
#maverick#
Hazard to Others
Posts: 209
Registered: 7-4-2011
Member Is Offline
Mood: hybridised
|
|
Refluxing
i was refluxing for the first time ever today, is the whole setup supposed to be closed, and i noticed at the top of my column the glass stopper kept
popping off, its probably cuz i lacked a keck clip and the silicone kind of melted might it be because i didnt apply it thick enough, im sorry this is
my first time ever refluxing/disitilling.
setup: 
grease i used: http://www.lowes.com/pd_53861-1366-88693_0__?productId=10921...
|
|
|
Magpie
lab constructor
Posts: 5939
Registered: 1-11-2003
Location: USA
Member Is Offline
Mood: Chemistry: the subtle science.
|
|
You should never heat a closed glassware system.
The purpose of the reflux column is to condense vapors from the pot, which then fall back into the pot. So there is no need to try to contain them by
sealing.
It looks like your glassware acquisitions are way ahead of your knowledge. You should get a good organic lab manual and read that beforehand.
The single most important condition for a successful synthesis is good mixing - Nicodem
|
|
|
Rogeryermaw
National Hazard
Posts: 656
Registered: 18-8-2010
Member Is Offline
Mood: No Mood
|
|
absolutely correct magpie. if you need to control the atmosphere in your system, use inert gas. a reflux should be performed in an open system. good
thing it wouldn't seal or you may have lost some nice glass or worse. better a joint to give out than for the glass to fail.
edit: if the grease you're using is melting, try automotive dielectric grease. a lot of people here have used it with success. personally i wouldn't
know. i got vacuum grease at elemental for fairly cheap, but many claim great success with the electronic grease.
[Edited on 10-6-2011 by Rogeryermaw]
|
|
|
#maverick#
Hazard to Others
Posts: 209
Registered: 7-4-2011
Member Is Offline
Mood: hybridised
|
|
Quote: Originally posted by Magpie  | You should never heat a closed glassware system.
The purpose of the reflux column is to condense vapors from the pot, which then fall back into the pot. So there is no need to try to contain them by
sealing.
It looks like your glassware acquisitions are way ahead of your knowledge. You should get a good organic lab manual and read that beforehand.
|
Will do magpie. Actually I have vogels practical chem book. I'll practice my techniques and with time I will get it
|
|
|
#maverick#
Hazard to Others
Posts: 209
Registered: 7-4-2011
Member Is Offline
Mood: hybridised
|
|
| Quote: Originally posted by Rogeryermaw | absolutely correct magpie. if you need to control the atmosphere in your system, use inert gas. a reflux should be performed in an open system. good
thing it wouldn't seal or you may have lost some nice glass or worse. better a joint to give out than for the glass to fail.
edit: if the grease you're using is melting, try automotive dielectric grease. a lot of people here have used it with success. personally i wouldn't
know. i got vacuum grease at elemental for fairly cheap, but many claim great success with the electronic grease.
[Edited on 10-6-2011 by Rogeryermaw] |
Wow. I feel a bit incompetent lol. And yea I'll try that or some Teflon tape. Once I have read up more on refluxing and distilation
|
|
|
Rogeryermaw
National Hazard
Posts: 656
Registered: 18-8-2010
Member Is Offline
Mood: No Mood
|
|
dude, don't be down on yourself. if you added the knowledge of everyone on this site into one person he would still have a long way to go. the good
thing is that you are using your brain for something other than keeping your head from caving in. but there is a lot of good knowledge here so asking
questions is a good start and most here will be glad to offer help for you as they have done for me and several others.
|
|
|
Magpie
lab constructor
Posts: 5939
Registered: 1-11-2003
Location: USA
Member Is Offline
Mood: Chemistry: the subtle science.
|
|
Vogel's is good. But for instruction in laboratory techniques I recommend the last book on this list by Pavia et al:
http://www.abebooks.com/servlet/SearchResults?an=Pavia+et+al...
The single most important condition for a successful synthesis is good mixing - Nicodem
|
|
|
#maverick#
Hazard to Others
Posts: 209
Registered: 7-4-2011
Member Is Offline
Mood: hybridised
|
|
| Quote: Originally posted by Rogeryermaw | | dude, don't be down on yourself. if you added the knowledge of everyone on this site into one person he would still have a long way to go. the good
thing is that you are using your brain for something other than keeping your head from caving in. but there is a lot of good knowledge here so asking
questions is a good start and most here will be glad to offer help for you as they have done for me and several others. |
thank you for the kind words 
|
|
|
#maverick#
Hazard to Others
Posts: 209
Registered: 7-4-2011
Member Is Offline
Mood: hybridised
|
|
looking into it as we speak
|
|
|
#maverick#
Hazard to Others
Posts: 209
Registered: 7-4-2011
Member Is Offline
Mood: hybridised
|
|
ok ill have another go at ethyl acetate soon, its a simple synthesis, thank you for your help guys
|
|
|
blogfast25
International Hazard
Posts: 10562
Registered: 3-2-2008
Location: Neverland
Member Is Offline
Mood: No Mood
|
|
Nice spiral cooler. But total overkill in all likelihood. A much cheaper Liebig cooler (air or water cooled) or even a nice Vigreux column cooled with
damp cloth will suffice for refluxing water based reactions, extractions or whatever takes your fancy.
Make sure you don't break that baby now... by top stoppering for instance  and
don't forget boiling stones!
[Edited on 10-6-2011 by blogfast25]
|
|
|
Arthur Dent
National Hazard
Posts: 553
Registered: 22-10-2010
Member Is Offline
Mood: entropic
|
|
If you need to reflux while preventing air from entering the vessel, use a tapered vent at the top of your column connected through a tube to a
bubbler filled with whatever inert/neutralizing liquid recommended for your reaction, use an empty conical flask with sidearm between the column and
the bubbler because as soon as you remove the heat, a vacuum effect will quickly draw in air, pushing back the liquid of your bubbler back to the
reaction vessel.
A nice setup you have. Yeah, I second Rogeryermaw suggestion of silicone dielectric grease from the auto parts store, it hasn't failed me so far.
Robert
--- Art is making something out of nothing and selling it. - Frank Zappa ---
|
|
|
The WiZard is In
International Hazard
Posts: 1617
Registered: 3-4-2010
Member Is Offline
Mood: No Mood
|
|
| Quote: Originally posted by #maverick# |
Wow. I feel a bit incompetent lol. And yea I'll try that or some Teflon
tape. Once I have read up more on refluxing and distilation |
This being a science form a less forgivingly person would
mention something from Chem. 101 — Boyle-Mariotte Law.
Once your apparatus reaches operating temperature you could
stopper it off, however .... when you turn the heat off you will
create a vacuum making it difficult to remove the stopper, and
possibly imploding you glassware.
|
|
|
The WiZard is In
International Hazard
Posts: 1617
Registered: 3-4-2010
Member Is Offline
Mood: No Mood
|
|
Think big go for the 4th edition.
Amazon.com
INTRODUCTION TO ORGANIC LABORATORY TECHNIQUES
A Microscale Approach (Brooks/Cole Laboratory Series for Organic Chemistry) [Hardcover]
List Price: $252.95
Price: $196.18 & this item ships for FREE with Super Saver Shipping.
|
|
|
#maverick#
Hazard to Others
Posts: 209
Registered: 7-4-2011
Member Is Offline
Mood: hybridised
|
|
| Quote: Originally posted by The WiZard is In | | Quote: Originally posted by #maverick# |
Wow. I feel a bit incompetent lol. And yea I'll try that or some Teflon
tape. Once I have read up more on refluxing and distilation |
This being a science form a less forgivingly person would
mention something from Chem. 101 — Boyle-Mariotte Law.
Once your apparatus reaches operating temperature you could
stopper it off, however .... when you turn the heat off you will
create a vacuum making it difficult to remove the stopper, and
possibly imploding you glassware. |
Thanks. Idk in a moment of stupidity I'm like I should stopper it off. Against my better judgement and knowledge.
[Edited on 10-6-2011 by #maverick#]
|
|
|
#maverick#
Hazard to Others
Posts: 209
Registered: 7-4-2011
Member Is Offline
Mood: hybridised
|
|
| Quote: Originally posted by blogfast25 | Nice spiral cooler. But total overkill in all likelihood. A much cheaper Liebig cooler (air or water cooled) or even a nice Vigreux column cooled with
damp cloth will suffice for refluxing water based reactions, extractions or whatever takes your fancy.
Make sure you don't break that baby now... by top stoppering for instance and
don't forget boiling stones!
[Edited on 10-6-2011 by blogfast25] |
Thanks. Yea I had boiling stones. I'll make sure to take good care of it. And I'll be on the lookout for a liebig
|
|
|
The WiZard is In
International Hazard
Posts: 1617
Registered: 3-4-2010
Member Is Offline
Mood: No Mood
|
|
| Quote: Originally posted by #maverick# | | i was refluxing for the first time ever today, is the whole setup supposed to be closed, and i noticed at the top of my column the glass stopper kept
popping off, its probably cuz i lacked a keck clip and the silicone kind of melted might it be because i didnt apply it thick enough, im sorry this is
my first time ever refluxing/disitilling. |
I would mention in passing — a coil condenser is not mechanically
ideal for refluxing. It is designed for straight through use, i.e.,
vapour in one end - distillate out the other. To much
heat and you will be blowing your chems out of the top of la
condenser. An Allihn bulb condenser is de rigeueu.
I know - Wili-P shows a coil condenser being used for
refluxing, however, note that it is being done under
vacuum/reduced pressure.
[Edited on 10-6-2011 by The WiZard is In]
|
|
|
#maverick#
Hazard to Others
Posts: 209
Registered: 7-4-2011
Member Is Offline
Mood: hybridised
|
|
| Quote: Originally posted by The WiZard is In | | Quote: Originally posted by #maverick# | | i was refluxing for the first time ever today, is the whole setup supposed to be closed, and i noticed at the top of my column the glass stopper kept
popping off, its probably cuz i lacked a keck clip and the silicone kind of melted might it be because i didnt apply it thick enough, im sorry this is
my first time ever refluxing/disitilling. |
I would mention in passing — a coil condenser is not mechanically
ideal for refluxing. It is designed for straight through use, i.e.,
vapour in one end - distillate out the other. To much
heat and you will be blowing your chems out of the top of la
condenser. An Allihn bulb condenser is de rigeueu.
I know - Wili-P shows a coil condenser being used for
refluxing, however, note that it is being done under
vacuum/reduced pressure.
[Edited on 10-6-2011 by The WiZard is In] |
i know its not ideal but it will have to do until i get a liebig or vigereux
|
|
|
turd
National Hazard
Posts: 800
Registered: 5-3-2006
Member Is Offline
Mood: No Mood
|
|
Apart from the correct objection concerning the coil-condenser, why is everybody using those silly plastic clamps? They break easily, melt easily and
- worst of all - look embarrassingly n00bish.
|
|
|
#maverick#
Hazard to Others
Posts: 209
Registered: 7-4-2011
Member Is Offline
Mood: hybridised
|
|
| Quote: Originally posted by turd | | Apart from the correct objection concerning the coil-condenser, why is everybody using those silly plastic clamps? They break easily, melt easily and
- worst of all - look embarrassingly n00bish. |
Instead of asking why. Ask yourself why not?
|
|
|
turd
National Hazard
Posts: 800
Registered: 5-3-2006
Member Is Offline
Mood: No Mood
|
|
I already gave the answer to that question. 
|
|
|
redox
Hazard to Others
Posts: 268
Registered: 22-2-2011
Location: The Land of Milk and Honey
Member Is Offline
Mood: Chalcogenetic
|
|
| Quote: Originally posted by The WiZard is In |
Think big go for the 4th edition.
Amazon.com
INTRODUCTION TO ORGANIC LABORATORY TECHNIQUES
A Microscale Approach (Brooks/Cole Laboratory Series for Organic Chemistry) [Hardcover]
List Price: $252.95
Price: $196.18 & this item ships for FREE with Super Saver Shipping. |
I bought this book (albeit an older edition), for $10 dollars including shipping! I don't think the newer versions are all that different.
My quite small but growing Youtube Channel: http://www.youtube.com/user/RealChemLabs
Newest video: Synthesis of Chloroform
The difference between chemists and chemical engineers: Chemists use test tubes, chemical engineers use buckets. |
|
|
#maverick#
Hazard to Others
Posts: 209
Registered: 7-4-2011
Member Is Offline
Mood: hybridised
|
|
Lol. Well I got em on the cheap and anything extra to help protect my investment doesn't hurt so why not?O
|
|
|
Rogeryermaw
National Hazard
Posts: 656
Registered: 18-8-2010
Member Is Offline
Mood: No Mood
|
|
i find that, under reduced pressure, the apparatus usually holds itself together well with no clips. sometimes to the point of being difficult to
disassemble. also, they have been terribly frustrating due to how easily they break on me. until i find myself trying pressurized processes regularly,
i probably will find their use limited. if i really do need a clip it's pretty easy to bend one out of copper wire. they're not incredibly strong, but
they work. just be careful not to try to force one over glass if it's too tight as scratches are detrimental to the longevity of your equipment.
|
|
|
Magpie
lab constructor
Posts: 5939
Registered: 1-11-2003
Location: USA
Member Is Offline
Mood: Chemistry: the subtle science.
|
|
I like the clips, especially those made of ptfe, because they assure that the joint is well seated, and I can manipulate the assembly without it
falling apart and breaking. I leave one joint unclipped, usually one with a joint pointing straight up, as a safety relief valve of sorts. If enough
pressure has built up to overcome the viscosity of silicone grease I want it to open up. I admit that they do look rather noobish, however.
The single most important condition for a successful synthesis is good mixing - Nicodem
|
|
|
| Pages:
1
2 |
![[*]](images/xpblue/default_icon.gif){kind=icon}
