pyrrole

8

Charmander, char!

I commandeered a recent Pokemon commission for more watercolor times. This one was all about Shmincke Hordam’s translucent orange (pyrrol, po71) which is SO GOOD. If you need a really good orange, that one. That’s the orange. It’s more tomato than carrot, a bright and clear mixer, and glows in tints and at masstone.

Also got to play with Winsor Newton’s cobalt Violet (pv14) a little. It’s unbelievably soft for being so vibrant, kind of a push-over. I do like how it separates really, really visibly from ultramarine in thinner mixed washes. Don’t know if it’s a go-to for anything just yet, still feeling it out.

Next up is a halloween themed tattoo design, among other things! I’m still building up my ‘keep doing stuff after work’ threshold. I would like to get where I’m painting a little bit every day. Slow going so far.

2

Crystals of sublimed 2-(trifluoroacetyl)pyrrole.

The raw reaction product what was an off-white crystalline compound with a melting point 50 °C was loaded in a test tube and left there for a few months. For now, these crystals formed at the wall what are perfectly pure 2-(trifluoroacetyl)pyrrole.

If this compound is left on a Petri dish for a day, most of it will sublime away.

3

I got my car all sorted out this week, so yesterday I went out to Lenz in Santa Cruz to buy some new paints. NEW FRIENDS!

Daniel Smith quinacridone purple (PV55) - Bloody dark purple, moody - wouldn’t call it leap-off-the-page vivid, but it’s brighter than dioxazine (and considerably redder), and pretty much completely shuts out perylene violet - which is a wonderful paint, but it’s also incredibly desaturated and a major lightweight wet-in-wet. PV55 works great in mixes for an actual royal purple with ultramarine and quin magenta, and makes stellar fleshy browns with transparent pyrrol orange.  

Sennelier Helios Violet (PR122) - Fancy-named FEROCIOUS quinacridone magenta. It’s damn near Opera bright, though without the fluorescence, or the lightfastness issues - which is AWESOME. Violet machine. Vivid terror-purple. This is my first tube from Sennelier and so far I’m super impressed, but considering doing a lightfastness test. It’s damn near ubelievably bright.

Daniel Smith Quinacridone Coral (PR209) - The red side of the quinacridone pigment family lists consistently pinky-pink/violet. Coral’s not really an exception, but it quite strangely…. red. Like… an honest blushy red. Really delightful, does awesome things in mixes with green.

Daniel Smith Cerulean Blue Chromium (PB36) - Get this blue. All around deeper than PB35 Cerulean and a little bit greeny, textured rather than “fluffy.” 

Daniel Smith Diopside - I kind of raise the eyebrow a bit when it comes to the primatek paints - they’re really good, but it’s easy to get dragged in by the novelty. Paint with gemstones!! They handle very differently. Like… they’re gooey. They actually feel gooey, viscous, thick in water. If you don’t keep your wash mix stirred, you’ll get really inconsistent results. They’re heavy!

All that said, they’re also really cool. I lean on Sodalite pretty hard, and am forever making eyes at Amethyst. Diopside caught my attention as a granulating alternative to Pthalo green YS, and holy hell it is. I love it. It’s a lot warmer than i was expecting, not nearly as tangy (the primateks are consistently a bit dull,) and it’s just as corny - wouldn’t use either straight out the tube. Love what it does with quin coral, pyrrol orange, yellow, blue, etc.

Daniel Smith Hansa Yellow Medium (PY97) - Speaking of corny, I like to avoid primary yellow like the plague. Because of this, I have a plague of yellows. Greeny yellows, orangey yellows, earthy yellows, and all this is great. But when something has to actually be yellow, it’s a huge problem. 

Hansa Yellow Medium is, honestly, nice. I’m not really sure how, but it’s both cool in tints and warm in masstone. It’s unexpectedly sunny and not cadmium-flat, or cadmium-toxic. Bless the cads and all, but cad yellow medium is probably what originally turned me off to keeping a middle-yellow in my palette. So far this one’s been a much more cooperative mixer and less opaque than cadmium, with more presence and all-around oomph than my previous go-to, PY175(lemon). It also lacks lemon’s magical talent of burning out your retinas if it gets out on its own.


The mixing charts are far from complete, but so far I’m really enjoying exploring the new additions! New favorites that work well with the old favorites, always a plus : D

5

Yesterday I have made something really new and really pure, a highly substituted pyrrole what crystallized on standing during the night to give these nice round crystals at the bottom of the flask.  

The best pictures from the blog, what are tagged as my portfolio, including these pictures, could be purchased at Society6 as a high quality great looking print: http://society6.com/labphoto now with a free worldwide shipping promotion till October 12, 2014, for every art print.

2

I am doing pyrrole chemistry for a while now and there is a quite interesting reaction with this. When I synthesize freshly a pyrrole (with free N-H) and add sodium-hydride, during the formation of the N-Na salt of the pyrrole an intense blue color appears as seen on the picture, but it fades to give a yellowish solution as the gas evolution stops. And it only works if the pyrrole is freshly prepared and it is in a pure form.

The color reminds me to the classic experiment, the solvated electron, what could be done by dissolving a piece of alkali metal in liquid ammonia.

4

From the previously prepared sodium methoxide solution (first pics) a heterocyclic compound was prepared by a base catalyzed condensation.

This is one of the worst reactions what I usually perform during the preparation of a substituted pyrrole. When the sodium salt of the heterocycle precipitates (that yellow thing on the third pics) I have to remove most of the solvent before the workup. The only problem is, that the yellow compound with the methanol behaves like butter, so it’s impossible to remove all of the solvent with vacuum and I can’t use heat, since the compound readily decomposes. 

After adding acids and water to neutralize the solution during the workup (last pics) the product should precipitate as a white crystalline solid. As seen this step in this case failed to give white crystals, but I obtained a lot off-white/brown solid floating in the solution):

I planned to try out a pyrrole synthesis what was described recently by researchers from Iran. In their publication one the reagents was DCC (N,N’-Dicyclohexylcarbodiimide). 

DCC is a white crystalline powder with a melting point 34 °C (93 °F; 307 K) what means that it melts during the summer and when I want to use it I can use the good old hammer and chisel method or try to melt it and use it as a liquid. In this case as seen I  melted it with the water bath of the rotavap.

The only problem with this compound, that it’s quite toxic and causes serious skin irritation if it gets on you.