« first day (1715 days earlier)      last day (2971 days later) » 

00:05
@Jan And it's 1-methyl-4-methylidenecyclohexane, not 1-methylidene-4-methylcyclohexane.
Jan
Jan
I was afraid it would be.
 
1 hour later…
01:08
Why is 2-monochloropropanoic acid stronger than propanoic acid?
@frostedcake Dou you know that –Cl is an electron-withdrawing group?
in a way, yes
that was what I could find out from my research
but how this makes it a stronger acid I'm not sure
woaahh chill, I have a massive exam tomorrow I'm just freaking out a bit
Loong has been really helpful, and I'm really grateful for that
@frostedcake You posted earlier one 2 times here...
yeah, within the last 24 hours or so, right? before that I haven't posted for like a year in this chat
this is my last question, and if Loong says he doesn't want to help me, then thats a shame, but its ultimately up to him and I respect that, I don't get why you need to come down on me like that
12
Q: Homework requests in Periodic Table chat?

Melanie ShebelI don't mind guiding users in The Periodic Table with their homework. If I get a question or two, I'll discuss it with the person. However, there have been times where users will sit in chat all night and ask question after question, seemingly completing entire assignments in chat. There have bee...

In chemistry and physics, the inductive effect is an experimentally observable effect of the transmission of charge through a chain of atoms in a molecule, resulting in a permanent dipole in a bond. == Bond polarization == Covalent bonds can be polarized depending on the relative electronegativity of the atoms forming the bond. The electron cloud in a σ-bond between two unlike atoms is not uniform and is slightly displaced towards the more electronegative of the two atoms. This causes a permanent state of bond polarization, where the more electronegative atom has a fractional negative charge ...
01:25
@frostedcake A strong acid can easily release an H+. How can you make this easier, if you push more electrons to the acidic group or if you withdraw electrons from it?
@frostedcake It's ok to ask questions in chat, but don't get impatient if you don't get any quick response.
no no
I wasn't being impatient, take all the time you need, you're the one helping me, I have no right to demand that you be faster or something, im really grateful for your help
ok, so do you see how electron-withdrawing groups affect the acidity?
@Mithoron Right I get your point, but these aren't question after question on an assignment, these are literally the 3 things that I have narrowed down in my org chem revision that I haven't been able to answer out of the 10 past papers I've done
wait, withdrawing electrons from it would make it easier for the H+ to be released because there is less attraction?
Consider a simple case: Why is the H–Cl molecule acidic?
There is a complete dissociation of H+ and Cl-
01:35
Yes, and why not into H- and Cl+ or neutral H and Cl?
because there is an ionic bond between an H+ and a Cl- ion
because this causes them to have full outer shells?
or H+ no shell
@frostedcake ok, that explanation works for Cl-
@frostedcake what gives this bond its ionic character?
is it a difference in electronegativity?
aha, yes
Do you know what electronegativity means?
this is all stuff I did in the beginning of last year, so let me quickly think about it
how attractive an atom is to a pair of electrons? so the Cl would be more attractive, so it would pull the electron pair away from H effectively
01:45
ok, the Cl attracts the bonding electrons in H–Cl. That makes it easy to create Cl- and H+.
I see where this is going
ok let me quickly look at the structural formula of the 2-monochloropropanoic again
Ok, the same principle works for other acid groups. You have to withdraw the electrons from the H in order to make H+.
ok, and (sorry if this is trivial) this principle works across the whole molecule, not just if they are bonded directly to each other
because obviously the Cl isn't bonded direclty to the H like it is in HCl
!!img/2-chloropropanoic acid
01:50
wow thats a cool feature
@frostedcake the effect works best if the electron-withdrawing group is close to the acid group
so the closer it is, the more effect it has essentially?
2-chloropropanoic acid has a pKa of 2.83
3-chloropropanoic acid has a pKa of 3.98; i.e. it is not so strong
You could add another –Cl group:
01:53
so to summarise: Cl is an electron withdrawing group, which pulls on the electron pair that the hydrogen is bonded to, which in makes it easier for the hydrogen to dissociate, which means that there is a greater number of molecules that dissociate, thus making it a stronger acid. Does that about bring it all together?
yeah, and that would make it even stronger right?
yes and yes
Hey hey hey :)
Cl is an electron withdrawing group, which pulls on the electron pair that the hydrogen is bonded to due to the higher electronegativity of Cl, which in makes it easier for the hydrogen to dissociate, which means that there is a greater number of molecules that dissociate, thus making it a stronger acid. Does that about bring it all together?
You can find some related pKa values in my answer here: chemistry.stackexchange.com/a/32662/7951
sorry just edited it to bring in the inductive effect
01:55
@MelanieShebel Hi!
yeah I can really see the effect
!!img/trifluoroacetic acid
This one is even better.
@Loong could I describe this effect as "the inductive effect as a result of the high electronegativity of Cl"
and also, thank you so much for your help, you have really been a life saver for me tonight
02:03
@frostedcake yes
 
7 hours later…
08:34
0
Q: What to do with redundant answers?

Quantum AMERICCINOSome of the answers seem to be redundant (especially the late answers). Although there is a policy towards redundant questions, there is no policy on redundant answers. What are your opinions on redundant answers? Do you think that they are harmless?

 
3 hours later…
12:03
Can AlCl3 chlorinate methane? methyl group of toluene? aromatic ring of toluene?
user228700
12:19
@para:
user228700
Dec 9 '16 at 14:05, by paracresol
@Kaumudi Fahr zur Hoelle
user228700
Dec 9 '16 at 14:14, by paracresol
How could you not know any German?! :O Shame on you! -_-
16:05
@Loong Well, it went ok...but I got the question with the Cl group for sure! haha
heh
now for some wonderful sle...oh wait 7 hours revision for my next exam lol
 
1 hour later…
17:23
I want to know the colour of difluorine gas ? Does anyone the colour of it ?
17:41
@A---B If you google for "fluorine gas", the search results page gives you a lot of pretty pictures of yellow fluorine gas.
Alternatively, the first sentence of Wikipedia mentions the colour:
Fluorine is a chemical element with symbol F and atomic number 9. It is the lightest halogen and exists as a highly toxic pale yellow diatomic gas at standard conditions. As the most electronegative element, it is extremely reactive: almost all other elements, including some noble gases, form compounds with fluorine. Among the elements, fluorine ranks 24th in universal abundance and 13th in terrestrial abundance. Fluorite, the primary mineral source of fluorine, was first described in 1529; as it was added to metal ores to lower their melting points for smelting, the Latin verb fluo meaning "flow...
17:55
@NotCorey Here's the first question for your proposed tag:
1
Q: How to perform a total synthesis on paper ? (Think before to make it in lab)

Hexacoordinate-CI studied organics chemistry during five years. All those years I just made reactions to made them, the only moments where I had to perform a synthesis on paper was during exams or exercises but all steps were given. So, even if, it was very interesting, there were no really fun to apply all this...

Hello
I haven't seen a total-synthesis tag
It's not created yet ;) The other day, @NotCorey was suggesting that we create one.
@Hexacoordinate-C You don't actually need to spend money. Both books are widely available in libraries, or if you wish, they are also available online.
@DHMO My book says yes.
18:09
@Loong thanks
18:36
@Mithoron actually, as far as I can tell, the answer is just "chelation".
However, I'm lazy to write an answer, so maybe someone else can come and collect the rep. :)
And maybe someone else will know more.
Maybe but more then a half of grigniard would be wasted
Yes. The paper uses 3.2 eq of Grignard, if I remember right.
Oh no another CO2 conversion in the feed!
And, actually I have another question to ask. :)
Wow ;)
18:47
I'm just trying to get a hat

« first day (1715 days earlier)      last day (2971 days later) »