The reaction at 12:15; wouldn't this reaction not react very much since Cl- is a better nucleophile than I- is? And I- being a better leaving group than Cl.
Hey Mike, I know it seems counterintuitive, but Iodide is BOTH a better nucleophile and leaving group but for different reasons. - Iodide is more "polarizable" than bromide and chloride. Polarizability is the ability for an atom to have its electron cloud MOMENTARILY not be evenly distributed around the atom (picture lopsided circle versus perfect circle). That type of electron cloud unevenness creates a small dipole effect, thus making an atom more nucleophilic. The bigger the atom, the more polarizable it is (which means further down a column = more energy levels added = bigger atom). Iodide > bromide > chloride. - Iodide is a better leaving group than both bromide and chloride because HI has a pKa of ~(-9.5), HBr has a pKa of ~(-9.0), and HCl has a pKa of ~(-6.0). As a result, iodide (I-) is the most stable leaving group. In my experience questions that attempt to exploit this concept are given in a format where you're given 2 reactions: reaction A where Cl- is the leaving group, reaction B where I- is the leaving group, and the nucleophile is the same. But you are asked why reaction B is faster than A, and the reason could be attributed to the fact that the I- is a better LG than Cl-. This video is an exercise on how to understand backside attack, invert stereochemistry when necessary, and learn characteristics of the rxn. But I can (and will) make a video about nucleophilicity to explain all of this. Does all of that make sense?
Appreciate the explanation, but there is no need to gender the molecules/species. When "he", the OH - attacks the Br, there is no reason to add that gender even when speaking informally. Thank you for the help anyway!
Kate mcconnell I’m sincerely sorry :( I swear I mean nothing by it, and I try to avoid using that phrasing (this video is a bit older and I actively try to avoid it now). I still make that mistake but try my best not to. I also mean nothing by using “guys” when saying things like “hey guys”. I appreciate your support, and I'm glad you found the video helpful.
Okkk come on, no need to feel special here and act like him "gendering the molecules" offended you. He probably wasn't even thinking like that and was just focusing on explaining the material to us. Anyways sincerely thank you for the explanation on the reaction, I really appreciate it!
Thank you very much for this great explanation. It was very helpful.
Thankyou....thanks a bunch for this.....it was really needed....
The reaction at 12:15; wouldn't this reaction not react very much since Cl- is a better nucleophile than I- is? And I- being a better leaving group than Cl.
Hey Mike,
I know it seems counterintuitive, but Iodide is BOTH a better nucleophile and leaving group but for different reasons.
- Iodide is more "polarizable" than bromide and chloride. Polarizability is the ability for an atom to have its electron cloud MOMENTARILY not be evenly distributed around the atom (picture lopsided circle versus perfect circle). That type of electron cloud unevenness creates a small dipole effect, thus making an atom more nucleophilic. The bigger the atom, the more polarizable it is (which means further down a column = more energy levels added = bigger atom). Iodide > bromide > chloride.
- Iodide is a better leaving group than both bromide and chloride because HI has a pKa of ~(-9.5), HBr has a pKa of ~(-9.0), and HCl has a pKa of ~(-6.0). As a result, iodide (I-) is the most stable leaving group.
In my experience questions that attempt to exploit this concept are given in a format where you're given 2 reactions: reaction A where Cl- is the leaving group, reaction B where I- is the leaving group, and the nucleophile is the same. But you are asked why reaction B is faster than A, and the reason could be attributed to the fact that the I- is a better LG than Cl-.
This video is an exercise on how to understand backside attack, invert stereochemistry when necessary, and learn characteristics of the rxn. But I can (and will) make a video about nucleophilicity to explain all of this.
Does all of that make sense?
Excellent
The fact that you're really cute helped keep my attention... ;)
not bad!
bro said gang
Appreciate the explanation, but there is no need to gender the molecules/species. When "he", the OH - attacks the Br, there is no reason to add that gender even when speaking informally. Thank you for the help anyway!
Kate mcconnell I’m sincerely sorry :( I swear I mean nothing by it, and I try to avoid using that phrasing (this video is a bit older and I actively try to avoid it now). I still make that mistake but try my best not to.
I also mean nothing by using “guys” when saying things like “hey guys”. I appreciate your support, and I'm glad you found the video helpful.
bruh who cares they're literally molecules
Okkk come on, no need to feel special here and act like him "gendering the molecules" offended you. He probably wasn't even thinking like that and was just focusing on explaining the material to us. Anyways sincerely thank you for the explanation on the reaction, I really appreciate it!