Nucleophile vs Electrophile

Nucleophile: is negative so is attracted to positive parts of molecules
has an electron pair it can donate
example reaction: (OH)-ion added to halogenoalkane, displacing halide ion to for alcohol. 

Electrophile: is positive so is attracted to negative parts of molecules, like a double bond (electron lover)
wants to accept an electron pair 
example reaction: Hydrogen bromide (H is delta +ve due to dipolar bond) added to alkene (with double bond) to form halogenoalkane. 

anonymous asked:

I just read your post about finally feeling like a chemistry student, and plssss teach me your ways. Im in organic chem right now and im having a hard time structuring everything... How do u do it?

I’ve started writing small headers in margins and I draw nucleophiles in blue and electrophiles in red, which makes learning the mechanisms much easier. I’ve made sure abbreviations are consistent and are all laid out on the front page of my notes, and back up my lectures with material from a book called “Organic Chemistry as a Second Language”, which I found in the university library. Organic chemistry is so hard, but when it comes to reactions eventually you’ll find you don’t have to learn them, you can predict them! The really bugger is the reagents though, unfortunately you just have to learn those off by heart. I hope things start to get better for you in organic chem, it’s a great subject to have under your belt and really widens your understanding of the sciences.
Have a nice week!

SN1 mechanism:
Stepwise mechanism that involves the addition of a nucleophile, the removal of a leaving group and the formation of a carbocation intermediate.
process: starting material-> TS1(transition state 1) -> loss of leaving group -> carbocation intermediate generated -> TS2-> nucleophile attacks electrophilic carbocation to form a new “s” bond -> product
in other words: (Nu: nucleophile, R: original/base molecule, Lg: leaving group, (s+): partially positive charge, (s-): partially negative charge, “—-“: weak/partial bond [semi-formed bond])
(Nu-) +RLg -> Transition state 1: R(s+)—-Lg(s-) -> Carbocation intermediate: (Nu-) + (R+) + (Lg-) -> Transition state 2: R(s+)—-Nu(s-) -> Product: RNu + (Lg-)
if this makes no sense I apologize

Did you know? Pyruvate is converted to Acetyl CoA with the Pyruvate Dehydrogenase Complex!

The PDHC is made up of 3 seperate enzymes, and uses 5 different coenzymes (TPP, FAD, CoA, NAD, and Lipoate)

TPP is used in decarboxylases and transketolases as well. It acts as an “electron sink: and creates a carbanion, which can act as a nucleophile, which will attack carbonyl group (in pyruvate in this case) and essentially “steal” two carbons, so that it can transfer them. THis is the E1 unit that does this and the next part(pyruvate dehydrogenase)

TPP transfers two carbons from pyruvate to lipoic acid in this case, attached to the E2 subunit. Lipoic acid is attached to a Lysine, which acts as a sort of long chain that can move between different areas in the complex. E2 swings from E1 after getting the acylated form of lipoic acid. E2 is Pyruvate transacetylase.

CoA has pantothenic acid as part of what makes it up. CoA, unlike lipoic acid, is not a prosethti group. it is “grabbed” by enzymes, and then released. The active thiol group is what reacts with the aceyl group on Acylated Lipoic Acid. 

At this point, Acetyl CoA is made, but Lipoic acid is now in a reduced form which is a problem ( I think?) so its gotta be oxidized. 

FAD and NAD+ I think are used to do this. FAD can either oxidize by 1 or 2, where NAD+ must be 2. 

So, FAD comes in and takes two Hs from the lipoic acid to make FADH2, and NAD+ takes those and makes NADH + H+ This is at E3 (dihydrolipoyl dehydrogenase I think?)

I think thats it?