Thin Layer Consternation
Earlier today, I was involved in a minor dust-up with some commenters over at Derek's blog. A central issue concerned my (admittedly quick'n'dirty) TLC, which meant to indicate the complete consumption of the acrylate starting material for Blog Syn #002.
Well, since I was already running another entry for #003, I decided to pause and take stock of my TLC tool-box: yes, I should use a ruler, and yes, a classic TLC would have lots more info (solvent system, stain, clearer labels, etc).
So, I took a sample from my IBX oxidation of methylnaphthalene to 2-naphthaldehyde (12 h timepoint, set up in straight DMSO with 0.1 volume of H2O). Results below:
Before anyone goes crazy, that's DMSO / H2O on the baseline, and the SM at Rf ~0.8. It's stained in potassium permanganate, which forms pale yellow spots upon heating. I circled the "UV-only" spots with a pencil before staining.
I'm guessing that the tiny new spot (Rf ~0.45) represents trace aldehyde. But, as you can tell, we're still a long, long way away from completion. Sad, because it was a lot more homogeneous this time!
Readers: How's my technique? Have any more pointers?
Well, since I was already running another entry for #003, I decided to pause and take stock of my TLC tool-box: yes, I should use a ruler, and yes, a classic TLC would have lots more info (solvent system, stain, clearer labels, etc).
So, I took a sample from my IBX oxidation of methylnaphthalene to 2-naphthaldehyde (12 h timepoint, set up in straight DMSO with 0.1 volume of H2O). Results below:
Before anyone goes crazy, that's DMSO / H2O on the baseline, and the SM at Rf ~0.8. It's stained in potassium permanganate, which forms pale yellow spots upon heating. I circled the "UV-only" spots with a pencil before staining.
I'm guessing that the tiny new spot (Rf ~0.45) represents trace aldehyde. But, as you can tell, we're still a long, long way away from completion. Sad, because it was a lot more homogeneous this time!
Readers: How's my technique? Have any more pointers?
