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[*] posted on 16-3-2017 at 07:03


Quote: Originally posted by arkoma  
Doing a test tube sized trial of drying agents for EtOH today. 3 Oven dried test tubes with oven dried Borax, TSP, or Sodium Carbonate (from SOLVAY Chemical, no less LOL) 7.5ml 91% EtOH in each. Gonna give them a few hours then decant a bit of each and add a xtal of KMnO4


Write it up when I get finished.

*edit* Chose those 3 agents 'cause I had them and after consulting the Merck Index seemed like good candidates.

[Edited on 4-17-2016 by arkoma]


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[*] posted on 17-3-2017 at 07:14


Synthesised some benzenediazonium tetrafluoroborate. It's more stable than I expected but you still have to keep it in a freezer and when you weigh it, you noticeably see how the mass decreases visibly quickly over time.



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[*] posted on 17-3-2017 at 12:52


Just finished making 19.0 mL of pyridine today following Nile Red's video. Something I DO NOT want to do again, pyridine smells really awful. Got a better yield than Nile though ;)
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[*] posted on 17-3-2017 at 13:03


How pure is it?



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[*] posted on 17-3-2017 at 13:52


Quote: Originally posted by JJay  
How pure is it?


Good question. Probably has a bit of water in it if anything.
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[*] posted on 17-3-2017 at 20:14


I've been thinking about making some pyridine....



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[*] posted on 19-3-2017 at 05:02


I did an experiment and it actually worked! While I don't yet know the exact yield or the purity, it apparently led to a large yield of my target molecule under reaction conditions that I selected using available materials, and in selecting those, I was shooting in the dark. I either usually have bad luck or am simply terrible at choosing reaction conditions, but in this case, I seem to have found my proverbial truffle in the woods.

Purifying it is going to be tricky... while I can easily eliminate most of the impurities, there is one that I expect perhaps 5% of that is going to defy most attempts at purification. It has a 17 degree lower boiling point than my target molecule, so I can probably separate them by fractional vacuum distillation.

I understand that this is all extremely vague... I'll do a writeup where I actually explain what I just made at some point.





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[*] posted on 19-3-2017 at 12:03


Sorry for the off-topic, but it really bugs me that so many people consider the smell of pyridine as being so bad and awful...
I don´t think it is that bad compared to for example pyrrolidine, this does smell(in my opinion) really, really bad but pyridine isn´t nowhere near, even triethylamine stinks worse than it(for my nose of course).
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[*] posted on 19-3-2017 at 16:10


There's things that smell worse than pyridine but it's still a pretty bad smell.
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[*] posted on 19-3-2017 at 23:48


Today I researched Jones reagent. I'm a little unsure why it is called "Jones reagent" instead of "Jones' reagent" but who am I to argue with the entire scientific community on a minor grammatical point.... I simply did a named reaction search on SynArchive and then looked at several experiments and identified oxidations that looked similar to the one I'd like to do and compiled a document detailing the reaction conditions and then did a search for chemistry websites and YouTube videos on the subject.

I came to the conclusion that with Jones oxidation: a) Exact stoichiometry is usually not used. b) Temperature control is usually not critical; an ice bath is often used but its main function seems to be to prevent reflux. c) The most popular concentrations are 3 M and 2.7 M., with some researchers not even specifying what concentration they are using. c) One thing that does widely vary is the concentration of the alcohol or aldehyde; some reactions require extremely dilute conditions and some use fairly concentrated solutions in acetone or even with no solvent. I am not quite sure what determines the amount of acetone used, but clearly, solubilities play a role. d) Standard procedure seems to be to drop a slight excess of the pre-mixed Jones reagent into a solution of the feedstock in acetone between 0 and 35 C and to allow to react for half an hour to an hour (perhaps monitoring the reaction with chromatography), neutralize excess Jones reagent with dropwise isopropyl alcohol, distill off the acetone, and then extract the product with a nonpolar solvent, but there are a ton of variations. e) It seems to be fairly selective for alcohols and aldehydes, mostly leaving benzylic and allylic carbons, double bonds and most non-oxygen containing functional groups alone, although it can oxidize many functional groups with long reaction times and/or high temperatures and/or pressures, and there are definitely exceptions.

It looks like the hardest part of determining reaction conditions is figuring out how much acetone to use.





[Edited on 20-3-2017 by JJay]




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[*] posted on 20-3-2017 at 05:37


I've done the Jones oxidation twice, and I didn't use acetone at all either time. The first time the substrate used was 2-octanol, and with vigorous stirring the reaction was able to go to completion even though 2-octanol is not ver water soluble. Due to the even lower solubility of 2-octanone, separation was trivial, and didn't even require an organic solvent. Yield was very good but I can't remember off the top of my head, and I don't have my lab notebook with me to check.

The second time, I did it with cyclohexanol. I didn't think much of the conditions, and tried to carry it out the same was as the previous time, but cyclohexanone is much more water soluble, so I was only able to recover about 20% by simple separation and salting it out. I can't remember if I tried to extract with a solvent or not... Regardless, my yield was much worse that time.




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[*] posted on 20-3-2017 at 15:09


JJay: I'm with you on questions of grammar. A good place to start is right on this forum. Ungrammatical statements and frequent misspellings and misused homonyms reduce any author's credibility.:)
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[*] posted on 21-3-2017 at 00:17


Oh, thanks. It wouldn't hurt to refer to Jones' reagent instead of using the common punctuation, although I think it is correct to refer to Jones oxidation.

I spent a few hours cleaning and organizing equipment. I have been mainly using vinegar to clean my glass; it's not taking off everything. In the next few days, I'm going to try some acetone, and anything still dirty after acetone treatment will be washed with vinegar, distilled water, piranha, then more distilled water.







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[*] posted on 21-3-2017 at 16:36


Your cleaning problems remind me of a dishwasher (a person, not a machine) in a laboratory where I worked ca. 50 years ago. We ran reactions in 3 and 5 gallon jugs (not pyrex), and some got pretty grungy. In these cases, a gentle tap with a steel-toed safety shoe rendered the jug (in the words of the dishwasher) "forever more clean!":D
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[*] posted on 21-3-2017 at 16:45


Haha. I'm actually surprised that some of it is as clean as it is. I used soap a 5 gallon bucket full of dirty glass, and it left a residue that doesn't easily wash off, and I can't wipe all of it. I'm pretty sure acetone will remove that; if not, I'd be very surprised if it can stand up to piranha.





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[*] posted on 26-3-2017 at 13:12


I got so exited when I first made nitric acid (which seems to be one of the biggest topics beginners discuss). I have been trying to use ammonium nitrate just because it was easier to get for me, but it always decomposed into laughing gas and nearly broke my apparatus 2 times. The second time I even inhaled some and my voice got deeper. But I went ahead and bought some KNO3, and It worked immidiately after using this. Although the distillation did work, I did not account on the No2 gas to form after I turned off the heat which traveled back into the boiling flask, creating a vacuum that sucked my NaOH mixture back into my poor nitric acid. Now I just forget safety and don't set up a NaOH trap anymore.
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[*] posted on 26-3-2017 at 15:30


I'm distilling some benzyl alcohol. I attempted this yesterday and was surprised at how poor my vacuum was and had to swap out the thermometer for safety reasons (the one I was using yesterday only goes to 150 C), so I shut down the distillation.

Right now it is distilling at 145 C. That means my vacuum pump is pulling only around 180 torr, which is worse than a good water aspirator. I've used it for a lot of filtrations, but this is actually only the second time I've used it for distillation, and the first time, the distillation simply failed. At least my short path distillation head seems up to the task. Time for a new pump....

[Edited on 26-3-2017 by JJay]




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[*] posted on 26-3-2017 at 16:41
Lead compound preparation


Background (If you're just reading for the 'procedural' part, then skip to 'procedure'):
I recently received a school project that was about problems passed on from the last generation (i.e. global warming) and I chose the custom topic of lead products such as paint and fuel. As a bonus to my presentation, I decided to prepare some actual lead compounds to showcase for the class! :D

I decided to prepare both lead carbonate and iodide as the white carbonate was a really common form of paint and I made the yellow iodide for the color. ;)

Procedure:
Lead iodide: 10.1 grams of lead nitrate (0.031 mol) was added to a beaker and stirred into solution. In another beaker, 11.6 grams of potassium iodide (0.070 grams, large excess to ensure the complete reaction of the Pb(NO3)2. With the potassium iodide was added water to turn it into a solution. The iodide solution was then added to the lead nitrate and lead iodide precipitated. (Theoretical yield of PbI2 was 14.3 grams or 0.031 moles.)

Lead Carbonate: 12.9 grams of lead nitrate (0.039 mol) was added into a beaker with water and stirred into solution. 4.20 grams of sodium carbonate (0.040 moles, excess to ensure complete reaction of the lead nitrate) was added to another beaker and prepared as a solution as well. The carbonate was added to the lead nitrate and a white precipitate crashed out. (Theoretical yield of lead carbonate was 10.4 grams or 0.039 moles.)

Both mixtures were filtered and the precipitates dried (In the meantime, the person doing the procedure spent the next 30 minutes going through the hassle of cleaning all of the equipment and adding lead waste to the appropriate hazmat containers.

Drying precipitates:

IMG_8926.JPG - 2MB

The very 'modern, government funded' waste containers ;) :

IMG_8927.JPG - 2.2MB

Finally, the products dried (somewhat) and were collected:

IMG_8928.JPG - 1.5MB

The yield of the lead iodide turned to be 15.9 grams or a 111% yield (11.2% error). Guess there were either contaminants or quite a bit of water...

The yield of the lead carbonate was 9.65 grams which turns to be a 92.8% yield (-7.21% error). Considering that lead iodide didn't seem all the way dry, I'm assuming my lead carbonate has quite a bit of water as well, meaning my yield should be even lower.

Though I guess this can expected considering I only let my samples dry for 8 hours outside.

Feedback or advice is always appreciated :)

Edit: Fixed some errors

[Edited on 3-27-2017 by A Halogenated Substance]




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[*] posted on 26-3-2017 at 18:36


I usually try to avoid using lead, mainly because I don't like cleaning up the mess, but that is pretty cool. I'm not sure about lead iodide, but you can dry lead carbonate in an oven (one that isn't used for food). If it gets too hot, it will decompose to lead oxide; you could make that happen over a Bunsen burner in a crucible if you wanted to for some reason.

--

I ended up storing the fraction from 145-150 C over molecular sieves. Where before I had some useless (to me) "green floor adhesive stripper," I now have a nice bottle of benzyl alcohol that I need to label.

IMG_20170326_181527.jpg - 358kB

[Edited on 27-3-2017 by JJay]




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[*] posted on 27-3-2017 at 06:34


I recrystallized some ammonium chloride. It seems to be dry now, and I think it is fairly pure, although I should do some tests on it if I need really pure ammonium chloride for some reason. I had reacted some dirty ammonium chloride with sodium hydroxide and bubbling the gas through water, which I then neutralized with hydrochloric acid and boiled to dryness. After recrystallization, I had washed it with 91% USP isopropanol, and it no longer smells of it or much of anything. I should really get some proper watch glasses at some point....

(Oh and in case you're wondering, the ammonium chloride got dirty when I foolishly washed it with IPA dry gas without checking the ingredients, getting some sticky brown additives into my nice ammonium chloride.)

IMG_20170327_062307.jpg - 403kB

I am going to attempt to make benzoquinone from acetaminophen again, probably later tonight.




[Edited on 27-3-2017 by JJay]




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[*] posted on 27-3-2017 at 08:56


Currently distilling nitric acid for the second time...
I don't have a Liebig with glass joints so my setup was rather interesting...

image.jpg - 1.5MB




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[*] posted on 27-3-2017 at 20:12


I just ampuled some mercury and iodine. Recently bought half an oz of platinum foil and another pound of mercury.
No titanium rod to weld on my MMO anode, so I sealed the connection in glass. A little epoxy keeps it water proof, hopefully it won't be degraded by the solution.

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[*] posted on 27-3-2017 at 20:17


I made some piranha solution and cleaned some glass. There is an experiment I want to do tonight, but I'm pretty tired and have a feeling it is going to wait until this weekend.



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[*] posted on 27-3-2017 at 21:52


Quote: Originally posted by JJay  
I made some piranha solution and cleaned some glass. There is an experiment I want to do tonight, but I'm pretty tired and have a feeling it is going to wait until this weekend.

Piranha solution is kind of a last resort for cleaning glass (at least for me it is). I usually use sodium hydroxide solution, so what did you have that wouldn't come off?
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[*] posted on 28-3-2017 at 01:52


I think it's hectorite clay. It has resisted every solvent that it's come up against, including piranha solution. I actually think sodium hydroxide will dissolve it, but lye eats glass, so I had hoped not to use it here.

Edit: I did a quick wash with a little sodium hydroxide, and it actually seems to have removed most of the suspected hectorite, though I can still see some residues if I hold the flask up to light. I'll definitely be trying that again in the future.

[Edited on 28-3-2017 by JJay]




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