The Periodic Table

CHM

12:05 AM

@Fx bye, get out now, will you?

Stack Exchange

12:53 AM

0

Q: Acid catalysed synthesis of ethyl ethoxymethylenemalonate

One synthesis of quinolones begins with the formation of an ethyl ethoxymethylenemalonate, as seen in this Organic Syntheses paper. I've been asked if the malonate derivative would be formed if methylmalonate was treated with trimethyl orthoformate with a catalytic amount of $\mathrm{H^+}$, with...

F'x

1:04 AM

@CHM I did, but now I'm back

CHM

@Fx good

I think using **text** is better than using \textbf{}

I'm going to use ** for chemical names

F'x

@CHM good; also, I think it might make web-indexing better

@CHM the link in your malonate question doesn't work for me; it opens a white page

CHM

to org syn?

@Fx does this work: orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv3p0395 ?

F'x

@CHM that one works

CHM

@Fx editing after reading the comment.

sure

F'x

1:10 AM

by the way, I liked the melting or melting-point

CHM

@Fx hmmm... add it back, then.

F'x

and would have thought "colligative properties" is only used for liquid-phase solutions

CHM

I assume a lot of people could use it, yeah

@Fx that's why I asked him to be clearer... I hadn't thought about eutectics before you mentioned. I was thinking more of an unpurified synthesis compound.

About the tags, you can add them back. I didn't think they were erased, I thought mine were appended.

F'x

@CHM no worry, but I am curious: do you have any example of colligative being used for a non-liquid solution?

regarding eutectics, it happens for all binary mixtures, and that includes a synthesized compound + its impurity

CHM

@Fx my training would make me say no.

Colligative properties of solutions is what I mean.

But then again

A solution can be solid, can it?

@LanceLafontaine good to take notice of the comments. If you can write a precision in the comments, you should consider adding it to the main question, and then removing your comment.

If you do that, I'm going to remove mine too. It keeps things clean and clear.

F'x

1:16 AM

@LanceLafontaine hi!

CHM

@Fx I'd think that the evolution of Tfus of a with augmenting Xb where a and b are metals would be considered a colligative property.

Since they're only one phase...

@Fx I've edited my question.

Stack Exchange

1

Q: Are there any ionic amorphous solids?

This question on NaCl crystalization actually got me wondering: are there any ionic amorphous solids? Like ionic crystals are crystalline materials of electrostatically-attracted ions, can ions form an amorphous phase? I can see no reason why not, but I cannot think of any example either…

solids amorphous-solids ionicity

F'x

@CHM yes; and I've found a patent for your reaction with clays: patentstorm.us/patents/5041619/description.html

CHM

@Fx hmmm.. interesting.

I'm confounded.

Some of my mates thought keto-enol tautomerism was important in the process- I think they haven't looked at the molecule carefully :P

F'x

@CHM well, that was my first thought too… but admittedly, my organic chemistry classes are a far distant memory

CHM

1:27 AM

@Fx "the aluminum silicates employed as catalysts"

@Fx Haha. I don't see how an ester would undergo keto-enol tautomerization, since.. it's not a ketone.

F'x

@CHM they're clays

CHM

@Fx you're surely more familiar with catalysts than I am.

What I'm pretty sure of, is that without the catalyst, the reaction wouldn't be very efficient.

F'x

but anyway, any chance of trans-esterification there? not that it yields the product you want, but I am wondering…

CHM

"If these acids or acidic salts are used without the catalysts, the necessary reaction times are lengthened considerably with a simultaneously clearly reduced yield."

Well, yes, there could be.

F'x

@CHM in fact, it's the only thing I could see happening with acid and no heat

but again, take that with a metric ton of salt

CHM

1:30 AM

There are actually many different paths one could follow, but they're not in the direction of the desired product.

Organic Chemistry be damned!

3

F'x

@CHM and that, Sir, is duly starred!

CHM

@Fx haha.

Do you think TD-DFT will revolutionize organic chemistry?

Come to think of it, it could put an end to the misery of "informed guessing"

F'x

@CHM the only thing I can see revolutionizing organic chemistry would be the undergrad and grad students creating a powerful union :)

CHM

Are they that underpaid?

And/or working with tied hands?

F'x

@CHM never done an internship or lab work in organic chem?

CHM

1:34 AM

@Fx no.

Lab work, for my diploma.

F'x

@CHM they you don't want any spoilers :)

but I found it to be extremely tedious and unrewarding work, and the powers that be typically don't care much for your opinion on anything

CHM

I'm not looking forward to one either. I'm more comfortable with chemical physics/physical chemistry.

F'x

put it another way: for some reason, organic chem appears to me as the most conservative and hierarchical field of chemistry

CHM

Bleh. That's what it looks like from the outside. Everybody competing to be the next best informed guesser.

What stinks about organic chemistry training, is the sheer lack of it.

F'x

@CHM when I was a student, it was considered the crown jewel of chemistry, so most of the hours devolved to it

CHM

1:37 AM

When you enroll for a degree in chemistry at a college, you'll get 3-4 organic chemistry courses, but only 1-2 organic chemistry labs.

At least, over here.

F'x

ah, we didn't practice much, though, indeed

CHM

@Fx I'm talking about lab experience.

F'x

@CHM got it, now

CHM

We'd need to spend a whole semester in an org.chem lab

Doing reaction after reaction, 5 days a week.

2 or 3 lab reports, nothing too heavy

F'x

@CHM but then nobody would do chemistry anymore, right?

CHM

1:39 AM

Haha, no I didn't mean do only organic chemistry labwork

F'x

I mean, organic chemistry stop being fun the day you realize that it's not only beautiful pen & paper constructions, but that sometimes the fucking yellow product is just a marroon liquidish molasses

CHM

Hahaha

F'x

anyway, I've got go and get some work done

see you later!

CHM

And when you spend 35 hours (in undergrad) synthesizing a product and only get to scrape a miligram or two from the sides of your flask...

@Fx bye

Nick T

2:09 AM

@CHM this is why organic chemistry blows; in biochem I can piece together a 100% stereo-specific compound with a weight in the hundreds of thousands of amu in some aqueous solution at 37°C overnight

CHM

@NickT marvelous.

Nick T

using like, digested cheese and some Marmite

CHM

I don't dislike synthetic chemistry that much, actually. I think it's absolutely necessary to learn, for a chemist/biochemist. What I dislike, is the way you need to guess around (once past a certain point, your intuition can get a beating)

See you're using enzymes

I'd like organic chemistry if we could use custom enzymes with 99% yield/stereospecificity/regioselectivity/chemoselectivity etc

But that's still far away.

@NickT Are you a student?

Nick T

0

A: Why do any impurities lower the melting point of an isolated substance?

Thermodynamically, you're considering the chemical potentials ($\mu$) of the liquid and solid(s), specifically the temperature where they're equal. In a mixture, the potential is lower as the disorder (entropy) has increased, so all things equal, it will favor the liquid over a purer solid where...

I think I'm wandering off the deep end there

@CHM yeah, entering a biochem grad program this summer

CHM

@NickT I'll read that answer next.

Nick T

2:14 AM

had my pchem II final today, figured I'd try to remember some of it by throwing it down :P

I don't know how really to handle the non-idealities of it (can a ever be >1?)

CHM

@NickT nice. What will you be working on?

Please don't talk about disorder when referring to entropy!

;)

Nick T

I like structural biology (where this figure is from), so looking at joining some crystal labs

CHM

Thou shall consult JChemEd.

Nick T

one of the ones I'm trying to set up a rotation with (unsure if it's a done deal right now) deals with active membrane pumps (ABC transporters) for things like drug resistance

CHM

@NickT so structural biology is like physchem applied to biology?

Nick T

2:22 AM

certain aspects

@CHM what's wrong with using "disorder" to refer to entropy?

CHM

@NickT because no notion of order/disorder are used to define entropy.

Nick T

don't hate on my layterms

CHM

it can be useful to think about it that way, but it is misleading.

A has greater entropy than B if there are more microstates that describe A's macrostate than B's.

But as mostly everybody else, I first thought about entropy as disorder. It's just that reading some JChemEd papers made me think a bit different about it.

Back soon.

F'x

2:55 AM

@NickT it's a nice answer, and the non-idealities are particularly highlighted by the Au-Ag alloy example I gave

CHM

My grandpa shared this with me : freedomflask.com

Funny.

Nick T

@Fx Ag-Au seems like it would be an ideal mixture (in the sense that all the interactions are equal), is it probably just because the mixture (alloy) solidifies as one, not pure?

my prof didn't know much about alloys or other solid mixtures when we covered that

not his bag so to speak

CHM

@NickT @Fx both of your answers are nice.

But I still think the question is too vague. What do you think?

Nick T

acido-basicity :\

acid-base?

or should the question it's on just be tagged buffers

F'x

@NickT acido-basicity and a synonym

or the other way around :)

@CHM I think the question is clear: it's a common chemistry textbook statement that you can characterize compound purity by measuring its melting point, because the melting point is lowered by impurities. He's asking why that is.

CHM

3:10 AM

What question are you talking about?

Nick T

6

Q: Why do any impurities lower the melting point of an isolated substance?

It is known that impurities in a desired isolated product lower the melting point of the mixture, even if the impurities melting point is much higher than the desired product. Why is that?

thermodynamics colligative-properties mixtures melting-point

F'x

same as you, re. "I think the question is too vague"

CHM

@Fx uh?

F'x

and I probably wasn't very clear, cause my answer is totally generic and does not deal with metal mixtures; in fact, I used the metal alloy only as a counter-example

Nick T

he pretty much summed up his rationale in the comment; it's something is lab prof said

CHM

3:12 AM

@Fx To me, that's the problem. The fact that there are textbooks devoted to the problem - questions should be more concices, imo. But it's not such a big deal.

Nick T

which is like the 2nd thing you learn about melting points in orgo lab; if your melting point is protracted (or much lower than it should be) your product is likely impure

CHM

@NickT yes, I saw. But I think he should edit his question to reflect that, keeping things neat.

F'x

@NickT the first thing you learn about melting points is that racing crystals on a Koffler rail with a friend is fun :)

CHM

@Fx what's a koffler rail?

Nick T

@Fx 1st thing for me was to not go so fast you had to repeat the experiment again...and again...and again...

and let the friggin thing cool between each go

F'x

3:15 AM

Kofler bench

A Kofler bench or Kofler hot-stage microscope is a metal strip with a temperature gradient (range room temperature to 300°C). Any substance can be placed on a section of the strip revealing its thermal behaviour at the temperature at that point. This melting-point apparatus for use with a microscope was developed by the Austrian pharmacognosist Ludwig Kofler (30 November 1891 Dornbirn - 23 August 1951 Innsbruck) and his wife Adelheid Kofler. In 1936, the Koflers and Mayrhofer published their "Mikroskopische Methoden in der Mikrochemie" [Kofler, L., A. Kofler and Mayrhofer, A. (1936)], ...

apparently, it's a "bench" in English :)

and it's Kofler, one f

Nick T

@Fx as opposed to what; Francois?

CHM

@Fx ah, ok.

@NickT Français.

F'x

@NickT yeah, I learnt that in French

CHM

@Fx The use of François is, funny.

I've never seen such an apparatus.

F'x

@CHM how do you measure melting points?

Stack Exchange

3:17 AM

1

Q: Chloroform and nitrile gloves

Many of us have experienced the failure of nitrile gloves when exposed to chloroform. What's going on at a mechanistic level when this occurs? I would guess that the chloroform dissolves some of the polymer into its constituent monomers, but I've never heard anything more definite than that. Is i...

polymers chemical-safety solvents halocarbons

CHM

We used microscopes with an oil bath and a thermocouple and a fan.

Pretty basic.

Nick T

capillary tubes in a heating apparatus

F'x

@CHM well, the Kofler bench is much more basic that that

thought I don't know how they make sure the temperature gradient is linear

CHM

@NickT yes, very similar to that.

@Fx that's what surprised me - a temperature gradient on a continuous strip of metal.. hmm

F'x

@CHM well, I'll show you any frying pan handle, you'll see if it's not a gradient on a continuous strip of metal :)

CHM

3:22 AM

Still, I'm wondering how you can control that.

Could make way for a nice question.

F'x

anyway, gotta go, bye again!

Nick T

I still don't get how the bench works; does it just have a temperature controlled heater on one side, then some huge heat sink on the other end?

CHM

Bye

@NickT that's good question material ;)

Nick T

don't have any idea how you could get very precise with that though

@CHM never used one, probably won't :P

CHM

@NickT same.

I had ChemBioDraw Ultra before... now that I've renewed my (college) subscription, it has become ChemDraw Pro.

Lots of features are gone, it's a shame.

No more NMR predictions, no more structure to name/name to structure function

:(

F'x

3:34 AM

@NickT I took the liberty of retagging "buffers" into "acido-basicity" on my question :)

as I doesn't really have anything to do with buffers

Nick T

@Fx can I at least call it acid-base? acido-basicity doesn't sound english

CHM

@Fx concerning your answer of the question about Woodward's synthesis, that one is also a case where I think the question is too broad.

F'x

@NickT go for acid-base, sure

but a buffer is a very specific type of solution, it's not a synonym of acid-base, that's my point

CHM

@Fx one couldn't provide a clear answer to his question. It would have to be a huge literature review, and a total re-thinking of the synthesis

Nick T

I skimmed it and saw titration, equilbrium, pKa and figured buffer

:P

F'x

3:39 AM

@NickT titration in a buffer isn't a lot of fun :)

Nick T

ionicity also seems a bit strange; ionic-compounds maybe?

F'x

en.wiktionary.org/wiki/ionicity

but it's not my first language, so retag if you feel it's better

CHM

I'd like more a question on a particular step, or series of steps, as I've written in the comment.

Nick T

I'm not talking about it not being a word, it just doesn't seem like a category

CHM

@NickT @Fx why not just ionic?

Then one can use it for more than one thing.

ionic - character, interactions, compounds, etc.

F'x

3:42 AM

@CHM works for me

CHM

@Fx the tag, or the B12 question?

F'x

hum, I got downvoted without any comment

@CHM if you highlight my message, you can see which of yours I was replying to :)

Nick T

@CHM but is one likely to be an expert on "ionic"?

F'x

the tag

CHM

o.O

I've never seen that

Nick T

3:44 AM

@CHM it only works on messages with the arrow on them

F'x

the B12 question, as I said, I think is a bit broad but somewhat fine; it's like asking "what methods are available to do X"; it's a bit more open-ended, but as long as the OP has looked a bit into or is posting context, they are fine to me

@NickT well, it only works with replies, yes :)

CHM

@NickT no, obviously. But tags are meant to describe the content in the question, so that people who are interested in the topic can view them more easily?

Not sure...

F'x

8

Q: Is activated carbon classified as organic or inorganic?

Organic compounds are typically defined as “molecules containing carbon”. Wikipedia states that there for some historical (read: non-logical) reasons, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the allotropes of c...

organic-chemistry nomenclature inorganic-chemistry classification

it makes me so sad

CHM

@NickT how do I select why message I want to reply to?

Nick T

@CHM highlight, hit the arrow on the right

F'x

3:45 AM

@CHM mouse over the message, they're a reply icon on the right

next to the star and flag icons

CHM

@NickT test

Nick T

@Fx I don't quite get the point of that question; what does it matter what it's called

CHM

Wow!

Haha.

I used to type it manually.

Hence why none of my @'s had arrows.

F'x

@NickT well, nomenclature's a big part of chemistry

the reason is I'm preparing a presentation on porous materials as catalysts, and I didn't really know where to put it in a traditional organic/inorganic materials division :)

CHM

@Fx being able to unambiguously name a molecule is important. Classifying molecules in huge realms, as in biology, seems a bit less easy and useful to do, to me.

Nick T

3:48 AM

yeah, but nomenclature for very specific things (a given drug) is totally different from saying something is organic vs. inorganic

F'x

@CHM well, categories are important, as is important to learn when and where they get blurry

anyway, I'd be fine with that kind of comment, but it's the lack of anything that annoys me

CHM

Gotta go.

Nick T

yeah, but solving edge cases seems like a waste of time

F'x

@CHM ciao

CHM

Have fun, fellas. See you tomorrow maybe.

Oh, one last thing

F'x

3:49 AM

well, as I've repeatedly said already, it's time for me to go too :)

Nick T

@Fx crying wolf

CHM

That question about d3s orbitals and color needs a bit more attention. I also think its not totally clear.

Nick T

:P

CHM

The answer given doesn't answer the question, as well as being wrong.

Review it when you have time.

Good night.

Stack Exchange

7:08 AM

0

Q: How does the choice of metal (oxide) catalyst affect the range of unsaturated compounds that can be hydrogenated?

In the hydrogenation of unsaturated compounds with hydrogen gas and a catalyst, the choice of palladium on carbon is able to hydrogenate alkenes and alkynes, but is unable to hydrogenate aromatic compounds. Using rhodium or Raney nickel, however, allows one to hydrogenate aromatics. How does the ...

organic-chemistry inorganic-chemistry

0

Q: How is Teflon adhered to frying pans?

The most notable characteristic of polytetrafluoroethylene (PTFE, DuPont's Teflon) is that nothing sticks to it. This complete inertness is attributed to the fluorine atoms completely shielding the carbon backbone of the polymer. If nothing indeed sticks to Teflon, how might one coat an object (...

polymer-chemistry

0

Q: What can I do if I don't get a phase separation between my organic and water phases?

Solvent extraction in a separation funnel is a very common method in preparative organic chemistry. But sometimes you don't get a nice phase separation between the organic and the water phase. What are the possible causes that can prevent the formation of two distinct phases, and how can you fo...

organic-chemistry phase-separation

Feeds

8:00 AM

Nick T has made a change to the feeds posted into this room

Nick T

Think I'll just flip that depending on room volume

LordStryker

11:32 AM

Good morning chemistry!

F'x

12:14 PM

@LordStryker and good morning to you

LordStryker

@Fx :)

We need a computational tag

like 'ab initio'

or modeling

F'x

12:29 PM

@LordStryker comp-chem?

with computational-chemistry synonym

also, I'd like it to be noted that this site was launched just the week I need to finish writing a sexy PRL manuscript… I consider it a conspiracy

LordStryker

@Fx sounds good. Whats PRL?

F'x

12:53 PM

@LordStryker Physical Review Letters

prl.aps.org

To enable MathJax in chat: meta.math.stackexchange.com/a/3297/3406

2

LordStryker

2:46 PM

@NickT Still waiting for my 'best answer' checkmark :P

LordStryker

4:37 PM

We chemists just don't act like this. chemistry.stackexchange.com/questions/71/…

bobthejoe

5:41 PM

@LordStryker, not sure what you mean. I'm willing to modify the question accordingly.

Andrew

6:01 PM

@bobthejoe I think he meant the reply, not your question. Your question seemed fine to me.

@LordStryker Were you still looking for answers to python questions?

LordStryker

@bobthejoe I was speaking of Georg's reply to my comment.

@Andrew I am except that I think my questions would result in a long, convoluted discussion and I don't think anyone would really have time for that. At the moment I've constructed a working SCF subroutine. Now I just need to have it give me the right answer. It really comes down to my lack of Python knowledge but I've been able to hash out a good majority of this stuff with the documentations.

Andrew

@LordStryker Ok, if you have specific questions, feel free to contact me separately.

LordStryker

@Andrew Thank you very much. I may take you up on that offer here in the near future. :)

Though I'll be sure to keep my questions very focused if I do.

Aarthi

6:18 PM

GUYS GUYS

user90

41 1

organic-chemistry reaction-control thermodynamics aromatic-compounds kinetics mechanisms

MY SIBLING!

F'x

@Aarthi LADY LADY

Aarthi

hahaha

yay i'm so happy. Aaron is one of the smartest people I know, and he loves chemistry probably more than me.

F'x

@Aarthi weird, he looks nothing like you

Aarthi

@Fx the pink and the white triangles are misleading, I know.

F'x

@Aarthi you'd look beautiful in pink, though

Aarthi

6:21 PM

aww

LordStryker

lol

Aarthi

here is me and sibling at my graduation last year: p.twimg.com/AeOYSmzCQAASSqf.jpg:large

LordStryker

@Aarthi Where is this at?

Aarthi

@LordStryker Indiana University. :D My alma mater.

LordStryker

Ooooh, cold!

Lived in Ohio for 12 years. Never going back :P

Aarthi

6:22 PM

hahaha

that was in May; much warmer then

LordStryker

Florida for 10 years.

F'x

@LordStryker I'm going to Florida on Saturday, first time

Aarthi

@LordStryker hahaha nice.

LordStryker

@Fx Where at in Florida?

F'x

@LordStryker West Palm Beach

LordStryker

6:24 PM

@Fx I'm from Central Florida but went to UNF in Jacksonville for my Bachelors

ahhh those were the days

that was when my life was its biggest rollercoaster

Aarthi

2

A: Michael reaction or nucleophilic attack at the alpha carbon of an alpha-beta-unsaturated ketone?

It must first be understood that Michael Addition is a special type of conjugate (1,4) addition where the nucleophilic species is an enolate. This will undergo 1,4 addition to the A-B unsaturated carbonyl. Organocuprates add in a 1,4 fashion. The mechanism behind this is not fully understood, bu...

am i really biased or does that sound really smart? /soproudomg

sorry sorry! i'll stop

:D

F'x

@Aarthi it's a fine answer

Aarthi

@Fx i know, i'm being ridiculous and annoying and n00bish.

as a total neophyte to sciences, i can only appreciate the smart words

/me giggles

Nick T

7:16 PM

@LordStryker it's like I should change my question to be "how do I calculate the strength of an interaction from a xtal structure" :P