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diggafromdover
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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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JJay
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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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