/cg/ - Chemistry General: Anime girl asking difficult questions

Found the article

its from some boring assignment I had a couple of years ago

pubs.acs.org/doi/abs/10.1021/om301010m

Lanthanides are fucking useless

>lanthanides are useless
any more useless than any of the other metals?

No ammonia without iron, lad

There are probably lanthanides in the machine you are using to view this post.

I'd argue that the actinides are far more useless.

This sounds like a contest with no winners

>probably

Aside from neodymium for hard drive magnets what ones?

en.wikipedia.org/wiki/Lanthanide#Applications

Yttrium for lasers and high temperature superconductors. Samarium for magnets. Erbium is used in fiber amplifiers. Gadolinium is useful for magnetic refrigeration. Cerium is used in lighter flints. Lanthanum oxide is used in fluid catalytic cracking. So basically a bunch of applications.

Most are luminescent, fluorescent, glow in the dark, all that jazz. Making them useful for phosphors. Pic related

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yea OP, it's not a very hard problem
did anyone try this?

>biochemists you can't just write 'reduction' and get a enantioselective product
of course they can, b/c it's carried out by a chiral enzyme

Pls help

Looks like a M6 helicene. Next?

Nope

Yep

That's a classic

yttrium isnt a lanthanide

>lighter flints

Fucking lanthanides

For some Lewis Acid chemistry, lanthanides are uniquely effective. This goes double for asymmetric catalysis, wherein the energetic margins are so small (most times less than 2 kcal mol-1; in exceptionally selective reactions these values approach 2.8 kcal mol-1) that the "right" Lewis Acid is necessary for high selectivity.

Cerium trichloride is useful for the Luche reaction, and in Grignard reactions with some ketones that are, without the CeCl3, easily deprotonated in alpha position by the Grignard reagent instead of being alkylated. Samarium diiodide can be used for the barbier reaction and for various kinds of reductions.

>it's an "user spills 75% of his reaction mixture on the bench and has to to the final step of the synthesis on 50 mg of compound" episode

Could be worse I guess, at least I'm not a natural products carbohydrate chemist

>wipe it up with a paper towel drenched in acetone
>put in glass frit; fill frit with acetone to let the paper soak
>pull vacuum to remove solvent
>rinse and repeat 3-4 times
>rotovap down
>repurify compound

Good call on stoichiometric lanthanides. I guess you can also include Ceric Ammonium Nitrate reactions (and the TLC stain CAM I guess?) as more practical applications.

>>wipe it up with a paper towel drenched in acetone
>>etc

m8 of course I did try that, but it was a carboxylate and I think it probably all just stuck irreversibly to the paper towels.

Then try washing it out with dilute acid to protonate it so it'll leave with the mixture? At this point you've literally nothing to lose by trying m8-E

It's too late user, it's in the garbage can now

RIP heterobiaryl compound

A few questions:
-Doesn't copper normally coordinate 'octahedrally'?
-Wouldn't the linear pieces be offset in general, leading to a ladder or chain-like structure?

>-Doesn't copper normally coordinate 'octahedrally'?
because it's Cu+ (one plus)
>-Wouldn't the linear pieces be offset in general, leading to a ladder or chain-like structure?
I had this idea myself, probably the cluster thingy is more stable because it's more nifty-looking

Cu(I) is happy in a tetrahedral environment, it's quite small so perhaps it has trouble getting 6 ligands around it.

You are right that you could get polymers as well as discrete capsules, but entropy favours the formation of a lot of small species with many degrees of freedom, rather than a big polymer chain that is more restricted.

>Yttrium
>lanthanide

>Doesn't copper normally coordinate 'octahedrally'?

Naw, because in ligand-field theory it's d10 and thereby orbital splitting doesn't come into play. Therefore it can only bond via its s and p orbitals thus making it tetrahedral only (much like carbon)

>File: 1472325621243.jpg (911 KB, 1468x706)
looks like a titty fight.

But isn't every enzyme chiral? Why should specific enzymes suddenly become stereospecific?

For the exact reason you just gave: that all enzymes are chiral. It's incredibly rare that both enantiomers of a chiral molecule have equivalent bioactivity; as a consequence, enzymes are incredibly stereoselective (not stereospecific, but close) because they only really need one of the two enantiomers in the first place. Therefore, the enzymes that survive evolutionary duress are the most efficient ones -- i.e. those that are most selective for the desired product.

>stereoselective (not stereospecific, but close)
Reminder stereoselectivity is about the products and stereospecificity is about the reagents

This probably isn't the thread for this but where would one get started in self studying chem?

"Chem" is pretty broad

I got a decent set of intro to general, organic and climate chemistry lectures but they are in Dutch

youtube.com/watch?v=tR0MX9hethM&list=PLZ0df6wQ5oO_7cnWpPbt6pMjBpJyMLByb

You should be more specific to keep it interesting, just general chemistry is too boring imo

seconded
it is in fact pretty broad
I suggest you start with genchem just to grasp basic logics, then venture onward to:
pchem - if you like rigour and shit
ochem - if you like zigzags and curly arrows
aaand I don't have any significant experience in other branches really, mostly because they are not much interesting

Biochemistry is alright if you are just looking for a hobby. Lots of reading possible, and the lab work is the most boring part

Start with Oxtoby for gen chem, get familiar with some thermodynamics, and then peak around at whatever interests you. Everything will be boring until you reach near the end of thermo

Thank you all I just got back from the store with some notebooks to write some notes while I watch this videos.

Make a throw away email account and post it please

My first publication today! Only Chem. Comm., so not that incredible, but exciting for me. How's your research going, Veeky Forumschem?

Waiting for some things on the lab to be fixed so I can finish the last part of my final assignment in my bachelors degree which should lead to a publication

but I'm a patient man, havent even finished my masters yet so why worry about publications

Yeah, that's why I said stereoselective you shit. Normal asymmetric catalysis has a huge disparity between selective/specific, but in enzymatic catalysis many enzymes are incredibly sensitive to the configuration of the starting material (see: any enzymatic kinetic resolution) so they are oftentimes best described as stereospecific. It's cool you know about definitions, but lame that you don't actually know dick about the chemistry at hand. :^)

Good for you! Keep doing science and keep publishing.

what's the order in which one has to learn chemistry topics? stuff like organic. analytic, and, uh, other stuff?
t. nonchemfag

Start with general chemistry for sure. Typical curriculum then moves to organic chemistry, then physical/quantum, then inorganic. I'd probably swap physical/quantum and then move into organic and lastly inorganic.

You're gonna need to complete calculus 1-3 before pchem And quantum/advanced orgo and stuff

I'm not doing very well in orgo (in my second quarter now) though I got top grades in gen chem (I know). Should I switch out of chemistry or will I like physical or inorganic more? At my school I can switch to a physical chemistry track and never take orgo again. I'm reading a book about chemistry and group theory and it's pretty interesting. But if the rest of chemistry is too similar to orgo I think I should go do a brainlet major...

just get good faggot

If you enjoy chemistry, stick it out

What's your problem with organic? It's possible you're just being taught badly, or trying to learn in the wrong way. Organic's kind of weird in that you have to memorise a bunch of semmingly unrelated reactions until at some point it all clicks and you get how reactivity works (obviously there will always be exceptions). That knowledge is relevant to all of chemistry, but organic chem is how you get there.

I've heard that if you're good at genchem, you'll be shit in o-chem and vice versa. For me, that was true also.

Synthesis time! Your goal is to synthesize DL-Leucine starting with Diethyl a-bromomalonate. If you want, hard mode: no potassium phthalimide.

Fucking biochemists, cant you just write reduction and move on

How's this?

- Darzens condensation between diethyl bromomalonate and 2-methylpropanal
- Heating with aqueous acid hydrolyses the esters, decarboxylates, opens the epoxide at the reactive alpha position, and causes elimination of the diol to an alpha ketoacid
- Leuckart reaction converts the ketone to an amine using ammonium formate

Fucking wish I had chemdraw rather than this shitty free ACD thing.

isis/biovia draw is nice and free

>potassium phthalimide

Gabriel synthesis is for scrubs, why not just substitute an azide group and use the Staudinger reduction?

>no potassium phtalamide
k i use sodium phtalamide :^)

>Gabriel synthesis is for scrubs
ebin

>substitute for an azide group
I think in this particular case, you would get an imine group instead. Pic related is what i have in mind.

forgot pic

HELLO CHEMIST FAGGOTS
the chem building is right next to my math department, and I happen to need about a liter of isopropyl alcohol.

is it tacky / creepy to ask some girls studying chem there if they can get it for me? do you generally have loads of that stuff standing around?

They literally offer the azeotropic 90% isopropanol in stores. Just get out of your basement

when I google "isopropanol" I get a chemistry shop that sells 6 liters for 20euros and a drug store that sells half a liter for 5euros.
neither is what I need and Im almost sure they dont sell this stuff in supermarkets here in germany

>Im almost sure they dont sell this stuff in supermarkets here in germany
In America we have 70% and 90%, I'm sure Germany has something similar. In the end you can always run some fractional distillation if you want to reach a higher concentration.

Azides don't just lose nitrogen like that, the way you've drawn it you'd be generating a nitrene with 6 electrons rather than a deprotonated imine.

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>pentavalent carbon
what the fuck

You fucking muppet

I'm just pointing out what made

checked

What he drew is completely legit, the ester is enolised. The red proton in was removed to make the enolate.

here, i drew some arrows to visualize what i imagine would happen. If a nitrene is generated instead, wouldnt the next thing that happens be electrons moving from the enolate group to the nitrogen (ultimately generating the same nitranion) so nitrogen can get its octet back?

I forgot to do my sapling learning quiz for chemistry. Is there any way to extend the due date from student access?

Looks plausible in the pic, but whether it actually happens is another matter.

I found this book in a Google result, from reading around it seems like alpha azidation of enolates is a fairly common method, so clearly they don't spontaneously lose nitrogen.

I wish I had a more comprehensive explanation, my best hand-waving attempt would be that you don't ever see fragmentations across an atom that already bears a formal negative charge, it's asking a lot for the enolate to push even more electron density onto that nitrogen. The enolate is actually already very stable being delocalised across both those ester groups, so it probably doesn't even "want" to extrude the nitrogen.

I sure hope this user is going to come back and give us the answer or at least explain the choice of starting materials.

Would Darzens even work here? Because it would involve SN2 on a tertiary carbon, which doesnt usually occur.

It's intramolecular and highly activated, though.

Having thought about it some more maybe an alternative route could be:

- Generate the Reformatsky reagent by treating diethyl bromomalonate with Zn
- React it with 2-methylpropanal
- Reduce out the OH using Et3SiH in TFA or some other deoxygenation method
- React just one of the ester grops to the acyl azide with 1 eq. sodium azide, then do the Curtius rearrangement and hydrolyse the other ester

I wanted to bump this thread so I decided to post a broken question

How is the question broken? I think either of the answers so far would work.

>How is the question broken?
Post Gabriel synthesis question and at the end decide to exclude the reagent used for such synthesis. Technically, this isn't a broken a question; you're correct. Also, I don't have any answers for this question. I decided to see what cute things /cg/ could do with respect to α-amino acid synthesis.

are you retarded

walmart probably sells isopropanol, it's a disinfectant.

>math department
Probably

>the answer
There are of course many correct answers, as always when you have a synth question.
>reduce out the OH using Et3SiH in TFA or some other deoxygenation method
might reduce the ester groups aswell, if it does there are surely other ways to get rid of the OH, but i found a more convenient way:
-react Reformatsky reagent with 2-methylpropanal and base to get a Knoevenagel kind of product
-reduce the C=C double bond with Strykers reagent
-proceed with sodium azide and Curtis rearrangement the way you described

Shit, it's incredibly obvious actually to just reduce a double bond rather than try to deoxygenate. I can't say I've ever heard of Stryker's reagent and would have just gone for something obvious like Pd/C and hydrogen.

The Amazing Mr. Circle !

>palladium

WHAT IS the job market for chemist like?

I'm currently finishing undergrad. I want to pursue graduate studies but I read absolute horror stories about grad school and how there is absolutely no light at the end of the tunnel, only death and the permanent smell of of DMS.

What do?
Current grad students, how is your life? Are you happy?

Can anyone comment on these (synthesis of testosterone and its esters).

Are these guys even close?

I have a basic understanding of chemistry - what would I need to learn to be able to do this?

What raw materials are going to be a problem?

For personal use. I live in where even if you need testosterone replacement, you can't get it.

elitefitness.com/forum/anabolic-steroids/synthesis-testosterone-dhea-your-kitchen-counter-662191.html

thinksteroids.com/community/threads/process-of-making-testosterone.134361616/

How to find out how legitimate pharma companies make this? Is it a trade secret?

Also, Gadlinium complexes f.e. with DOTA for MRI in humans. Cerium used to be used for redox titration. All of them for general magnetism jazz in intermetallic phases, though you pretty much covered that.

I want to know this soon.
Would different areas, like materials vs organic,be better than others?
I'm interested in stuff like nano medicine, biophysics/biochem, or molecular machines but I'm sort of worried of what I will actually be able to do.
I might just switch to chemE and take an extra year. Probably to much of a brainlet to make a significant contribution in research

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