chemrox
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practice helps a lot
About a year ago I wrote that I was out of practice and things hadn't been working out in the lab. I said I needed to practice technique. I ran lots
of distillations and simple preparations. Lately procedures have been going through to expected results and good yields.
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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Klute
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Glad to hear that. Hopefully this will help many that are too impatient and want to jump to complex reactions with minimal experience...
Good idea posting this!
\"You can battle with a demon, you can embrace a demon; what the hell can you do with a fucking spiritual computer?\"
-Alice Parr
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BromicAcid
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Indeed, lab technique is impossible to learn entirely simply by reading about it. After I became a production chemist I realized how woefully
inadequate the lab technique I had developed on my own was. Just because I had done a few dozen distillations didn't mean much at all.
With distillations expecially, you learn when you can push them and how far, and when to leave them alone at the minimum heat. Bumping was something
I used to preceive as a function of what it was you were distilling but now I realize it is more related to the experience of the chemist. It's
amazing how much practice helps things.
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chemrox
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@bromic- As a production chemist I would love to hear some of what you've learned about bumping. The little I've learned is that sometimes gently
raising the temp and using uniform heat sources can be as effective as stirring in controlling the noxious bump. I've been doing a lot of work in a
100 ml flask with a short path still. One bump would sort of wreck the whole process ... particularly with one of the reactive distillations. And we
can analyze and explain up to a point but as you know there's a certain feel to things that just comes with lots of repitition and doing. Another
thing I didn't learn in school was how to keep a proper notebook. All my experiments start off with a table of the physical properties, quantities,
moles and equivalents of all my reagents and expected products. I include information sources in the table. I tape in 50% color copies of my TLC
plates and IR scans where used. If there's a general procedure I copy and tape that in as well. I ususally do my weighing arithmetic on the left
hand pages and keep them as part of my record. It's amazing how that little discipline has reduced calculation carelessness. When the book starts
filling up I number the pages and make an index in the front.
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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Magpie
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I second the value of a great deal of lab experience. My home experience has been more varied and challenging than what I did at school or work.
Home chemistry experience has given me more insight into why an author is using certain techniques.
I keep a detailed notebook and when timing is a factor I write the time of events in the left-hand margin. I also strongly resist the temptation to
stop keeping records when I know the experiment is going south. That is when you need to be most diligent as you are going to need to know what NOT
to do when you try again.
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chemrox
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@magpie- He "strongly resist(s) the temptation to stop keeping records when I know the experiment is going south." Good point and thank you for
posting it! very important.. most important to track mistakes and sometimes the behavior and/or appearance of the mixture can provide clues to what
might be changed next time around. Thanks again m!
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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Saerynide
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Thats a very good point. I tend to start mixing random crap in (like adding different solvent or salt or whatever) in a desperate and futile attempt
to save the experiment, and then I forget to keep records....
But then later I always realize those random additions yield something unexpected and so I want to find out more, but by then I've lost track of what
I did to get there 
"Microsoft reserves the right at all times to monitor communications on the Service and disclose any information Microsoft deems necessary to...
satisfy any applicable law, regulation or legal process"
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crazyboy
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How many of you keep records and how do you write them (how detailed any format?) I never keep records but I really should get in the habit. I think I
will dedicate a notebook to careful observations, calculations, times etc.
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Saerynide
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I just scribble illegibly. Usually, I have a hard time making out 1/4 of what I wrote because when somethings worth writing down, theres usually also
too much going on for me to stop and write neatly or think carefully about what I write. So its just a vomit of numbers and stuff circled and strings
like "turned red!!!" or something like that.
The worst part is later trying to match the numbers/measurements to the item... "Shit... What's 36.89?" "Is that 12 mL of this... or that.... fuck"
"Microsoft reserves the right at all times to monitor communications on the Service and disclose any information Microsoft deems necessary to...
satisfy any applicable law, regulation or legal process"
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Darkblade48
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I'm not as meticulous as chemrox as I don't start "my experiments start off with a table of the physical properties, quantities, moles and equivalents
of all my reagents and expected products. I include information sources in the table." It's definitely a great thing to do, but as I am not a chemist
by profession, I don't feel there is a need to be that detailed for what I am doing.
I do, however, work out the reaction formula, expected products, theoretical yield, and do all my calculations in the notebook for future references.
Also, I'll write out the procedure as well as any changes that I make. Any results that I get, I'll also try to take a (digital) photo and archive for
future reference.
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watson.fawkes
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All this discussion has me realizing that a lectern shelf specifically for the lab notebook would be a fine addition to the interior architecture of
any laboratory. If you value it, it makes complete sense to make a dedicated space for it.
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chemrox
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well: having said all this wonderful stuff I have to come clean about a crystallization screwup. I was trying to recrystallize a nitrogen
heterocycle (yet to be characterized) that I had in hot acetone. I thought I'd make nice crystals by adding a less polar solvent and I had n-heptane
lying around. After making sure acetone and heptane mix freely, I poured heptane into my warm acetone/solute mixture. The two liquids separated and
when the solute finally crystallized in the refrigerator, there was about half as much as before. However, after the solute solidified, the
supernatant liquid was homogeneous. I poured off the now, or once again, homogeneous mixture to let the heptane/acetone/solute remaining evaporate
and crystallize. I've only seen, heard of H2O/solvent mixtures doing this until now. Could we say that the heptane got "based out?"
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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Klute
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Basicly your polar product acted as NaCl would with H2O/IPA for example...
Comming back to the notebooks, I keep some pretty detailed notes, with moles quantities, molar mass, density, equivalents, etc, and describ the
reaction conditions and changes. I have always found it to be very reassuring when performing a reaction again a few months or even years after, as
you cna really relate to each change in appearance.
At first, I didn't keep any notes, and realized that each time I started a reaction again, I started from the beggining, and hardly "learnt" from my
mistakes. Keeping notes ables you to optimize a reaction even if you only do it twice a year. Having some suggestions and comments at the end are
quite helpfull too, when you forgot what you had in mind the first time you did the reaction.
It's also pretty valuable when doing derivatives, analogues, etc to compare the reaction appearance and yields when adding any other substituant or
similar.
An dit's not that boring to write, actually it's even a pleasure at times! 
\"You can battle with a demon, you can embrace a demon; what the hell can you do with a fucking spiritual computer?\"
-Alice Parr
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woelen
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I use my website as a notebook. During experimenting I may write down something (e.g. numbers), but the real working out of the experiment is done in
my website. I do not refer to the pages with the pictures, videos and so on, but to the text-only experiments, which I also have on the website. Doing
so forces me to keep track of all the things I do, and it has the added benefit, that I can easily search things lateron (there is a basic search
engine in the web-application).
I also do this fior another reason. If I ever will have a visit from some three-letter or four-letter offical organisation, then I can prove without
any doubt that I do science-related things. There is an extensive log and megabytes of information, and a cook or a bomber definitely does not have
such a record. So, the log serves two purpose, organising things for myself, even if things are not interesting (there are experiments on my website,
where I simply write that nothing seems to happen), and some (only some!) protection against over-zealous officials.
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Panache
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i'm lazy and rely on my security video as a notebook for anything over and above the basic procedure i am trialling, i do talk to myself a great deal
though and tis proves valuable. Its more entertaining than notebooks, especially when a song i like comes on the radio i start dancing. ...its a
beautiful life oh ah oh oh.....now wheres that bottle of fizzy bubbler.
[Edited on 5-12-2008 by Panache]
[Edited on 5-12-2008 by Panache]
[Edited on 5-12-2008 by Panache]
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