The Periodic Table - 2017-12-31

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5:51 AM

@orthocresol Mind a question? O:)

I had a look at Ben Norris' answer here:

16

A: What's the difference between a nucleophile and a base?

The two are related, in that most nucleophiles are (Lewis) bases and vice versa. Some good nucleophiles are also strong bases, e.g. $\ce{HO-}$. However, a species can be a good nucleophile and a weak base, e.g. $\ce{I-}$; or a species can be a weak nucleophile and a strong base, e.g. $\ce{t-BuO-}...

There's this bit on nucleophiles:

user image

I understand that iodide is a good nucleophile (in water). Would that mean the generic "Nu" used in the reaction (in the image) refers to any nucleophile stronger than iodide?

( Just want to know if I interpreted that right, or if I've overlooked something )

(Ah, since it's a primary alkyl halide, I guess it's SN2)

5 hours later…

10:50 AM

@Loong Because I can read it, and calling it an edition annoys you

It doesn't annoy me. I just wanted to clarify that this document is just a draft and not an official release.

11:43 AM

@orthocresol And then we could also fix the names in the Wikipedia article.

I actually do that a lot: Reading a question concerning a compound on Chemistry.SE and then checking the corresponding Wikipedia article, first of all correcting the names

12:00 PM

So, I have fixed the worst problem with the names in Wikipedia; but that still doesn't answer the question.

1 hour later…

1:20 PM

@Jan - san (and orthocresol), mind giving this a look? :-)

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The answer's option c, but I can't for the world figure out how they arrived at it :-(

I managed to get option b though (route number 1) :-D

And I twiddled around with cyclization (route noumber 2), but that didn't really end well...

user image

< Crosses fingers and hopes it ^ isn't a pain to read >

1:43 PM

@Alan ketones are more reactive than esters

Ah, I was AFK, sorry!

<Reads>

@Loong Hmm, but isn't the carbonyl carbon of an ester more electrophilic?

The -OR bit contributes ^

@Alan No. Pi-donors reduce the electrophilicity.

@Loong Pi-donors?

I can see two lone pairs on the oxygen in -OR though...

But I'm unfamiliar with the "Pi-donor" term :-(

2:00 PM

The -OR has available lone pairs.

The carbonyl can accept such electrons into its pi system.

< Thinks about it >

@Loong I'm not quite sure how that works... :-(

^ Does it involve the carbonyl oxygen gaining a unit negative charge?

user image

like this

replace the -OH with your -OR

and the double bond with your C=O

Aha! I see! @Loong Thanks! (I'll try applying this to the question, and see what happens) :-)

For your question it only means that the first step is addition to the ketone.

@Loong Which would mean option a is correct :O

2:08 PM

No. You don't make the workup so fast.

First you get the alkoxide.

< Nods >

And then cyclization?

^ Some sort of internal nucleophilic attack on the other carbonyl carbon?

Yes the alkoxide is a nucleophile. And there is a suitable electrophile in range.

:O

Woot! Let me try this out! :-D

I'll ping you when I'm done, thanks a ton! :-D

Holy Cow, it is c! (acid workup after cyclization worked) \o/

< Bows in reverence to @Loong >

O:)

:-)

@Jan Thanks, but Loong helped me out with it. (sorry for pinging you)

@Loong You're an organic chemist? :O

2:15 PM

no

< Waves at orthocresol >

@Loong Computational (like Martin)? O:)

@Loong I think you mentioned this before somewhere. I see the "no longer recommended" :)

@Alan No. I am a radiochemist.

:O

That the same as a nuclear chemist?

yeah, almost

2:18 PM

< Does a little jig >

How close have you been to a fission reactor? :O

<- High-school student. Very curious about it O:)

@orthocresol Your question gets a bit more complicated, basically because silane is not a PIN, but for example tetramethylsilane is.

@Alan To the actual reactor pressure vessel? Maybe five metres.

I was too quick to rule out bis(tms)amine, I guess?

Yes. I think it's still in.

Ok, I'll rephrase that and get rid of the extra -1- as well.

(Had to google "reactor pressure vessel" first) Yup, looks like that's what I had in mind. :-)

< Drools in awe >

Was that 5 metres of concrete? (or tungsten carbide?)

2:24 PM

Depends. In most running PWR units it was just air plus concrete slabs. In the BWR's next door it was mostly water. My current unit is not in operation yet, so it's just open in the air.

^ Ah, so there wasn't any fuel in it? :D

(Psst, how close have you been to a "loaded" reactor pressure vessel) >:-)

@Alan No. My current unit doesn't have fuel in the reactor yet.

@Alan Maybe five metres.

5 metres. Do you guys wear protective gear?

(Helmet aside) :3

Only against spreading of contamination

Contaminants? Like dust (or something more nefarious)?

( Hope I'm not bugging you; just curious ) O:)

2:32 PM

usually activated corrosion products

Don't know what specific examples that includes, but I think I get the idea. :-)

The classic example is Co-60.

Mind another question? (organic again) :3

You have an orthocresol here. ;-)

@Loong Where's the Co-60 usually produced/formed? In the fuel?

@Loong Ah yeah, but since you're clearly active now I thought I'd ask you first O:)

I'll ping orthocresol if you're busy O:)

user image

2:36 PM

@Alan No. From the cobalt content in stainless steel and other metallic construction materials.

user image

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( Pardon the crappy handwriting )

@Loong Ah! And that gets irradiated, yielding Co-60?

^ In trace quantities

yes

:-D

2:50 PM

@orthocresol Got some time to spare? O:)

sorry tad busy trying to apply for graduate study

Ah :-)

Martin - マーチン

3:18 PM

Happy New Year from Japan!

4

3:42 PM

Anyone know how an alkoxide would react with an ester?

I can see it attacking the carbonyl carbon, but I'm not sure what transpires afterwards :/

> Carboxylic acid derivatives like esters, anhydrides, and acid halides react well with good nucleophiles like HO- and RO-

Ah, is it similar to adding a Grignard Reagent to an ester?

3:56 PM

@Alan You're at the point where you would be well served by picking up an undergraduate textbook and reading it. The usual recommendation is Clayden.

I borrowed "Morrison and Boyd" from the library :-(

I'll try to get my hands on Clayden then :3

never read that, so can't say anything about it

I see. Thanks for the recommendation! :-D

4:46 PM

@Alan M & B is OK

:D

Also, Hallo! o/

@Alan o/

:-)

But what would you prefer?

Between Clayden and Boyd

I don't know clayden enough to tell

< Nods >

I've heard of Clayden only recently, and orthocresol recommended it as well (still haven't been able to give it a look) :-)

Thanks for the vote of confidence ;-)

4:49 PM

no probs

I take it you're a Chemist too? :D

Well, I know quite a bit about chemistry for sure

I can tell (from your answers) :3

About some other stuff too :)

3 hours later…

Geoff Hutchison

7:43 PM

Happy New Year from Pittsburgh!

4

I've got a few ideas to start off the "molecular design golf" in 2018. :-)

@orthocresol - good luck in applying to grad school. Let me know if you have questions from the admissions side.

8:20 PM

@Loong, if you are up to it, the Wikipedia names for the salts also need to be changed (LiHMDS, NaHMDS, KHMDS). I guess the corresponding PINs would be "lithium 1,1,1-trimethyl-N-(trimethylsilyl)silanaminide"?

etc.

sigh more work

I wonder why they didn't prefer the multiplicative name.

It would be easier...

generally they do:

5

A: What is the rationale of the IUPAC name for DDT?

According to the current version of Nomenclature of Organic Chemistry – IUPAC Recommendations and Preferred Names 2013 (Blue Book), a structure with two or more identical units that are linked by di- or polyvalent groups can be named in two ways: by ordinary substitutive nomenclature, in which ...

@GeoffHutchison Thanks! I'll ask you if anything pops up. Most of it is actually done, I'm just finalising some of the stuff I've written, mainly the statement of purpose. (Only applying to UK.) P/S I used Avogadro to generate some pretty images for a presentation at my group meeting, which went down fairly well, so thanks for that too!

@Loong I'm sure you already know it, but work on Wikipedia benefits so many people. To a lesser degree, work on SE does that too, which is one factor which motivates me to try and write thorough stuff that is properly referenced etc. I never really got into WP editing though.

I hope so. I have more than 1000 edits on the English Wikipedia.

8:31 PM

So, are you a organic chemistry genius or a bot?

:)

A bot.

!!name/CH4

If you see a preferred IUPAC name on Wikipedia, there is a good chance that it was my deed.

@orthocresol Rover's Dog Shampoo

Haha, I'd forgotten about that one...

I had to look it up.

8:40 PM

@Loong There's one that I did.

999 more to go

nice

I still need 19 nomenclature answers for the gold badge.

What're the requirements for a gold tag badge?

200 answers, 1000 score

That's a lot of nomenclature answers you have.

My closest gold tag badge is org-chem (130/200).

1 hour later…

9:58 PM

@TanYongBoon You may be interested in this:

25

Q: Does OP mean “original poster” or “original post”?

In an online forum, OP means "original poster," but can it also mean "original post?" For example, instead of saying To answer the OP's original question... could one instead say To answer the question in the OP... or would this be an improper use of the term?

meaning terminology abbreviations expression-choice initialisms

Happy New Year from Finland!

3

10:12 PM

> 4,444 questions with no upvoted or accepted answers

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