#Wang_org gem-Difluorination of Alkenyl MIDA Boronates: Synthesis of α- and β-Difluorinated Alkylborons
1 4510 hours ago
Actually I might go for the Mercury poisoning 😷💝
14 102011 hours ago
A pantomime showing how some Fischer projections relates to the 3D structures they represent. The first one is a meso compound - it is identical to its mirror image. The second and third are enantiomers - ie. non-superposable mirror images!
Be careful how you mentally manipulate the Fischer projection - remember it is a shorthand *representation* of a 3D molecule.
1 4412 hours ago
A common mistake when manipulating Fischer projection is to forget that it's a 2D shorthand representation for a 3D object (a molecule). AND, that there are two important rules that need to be followed:
1) Horizontal bonds go to atoms that are above the plane (of the paper, page, board, etc)
2) Vertical bonds are to atoms below the plane.
So, when you start rotating the 2D Fischer projections, some things are ok and some are not!
Rotating the Fischer projection within the plane of the page is fine - everything "up" stays "up" and everything "down" stays "down". But, rotating the projection around axes that aren't in the plane of the page, as *the projection itself* was a 3D object, will screw things up! Depending on how you do it, something that is above the plane may end up below and vice versa, in ways that don't fit the conventions for how to draw the Fischer projection. Chaos ensues!.. and bad exam grades! 😱
I loved this lab. One of my favorite lecturers was Dr. Bob, whose reputation put the fear of God in me.
0 217 hours ago
Trying to get my life together so of course I'm going to procrastinate and Marie Kondo my room instead. Found more goodies from undergrad.
1. Physical chemistry midterm covering quantum. I have no idea how I passed that class, but that was curved to a C I think. I owe my life to my TA that quarter. She was a wonderful human being who started each session with a nerdy science joke and had a dog named Argon because it was usually inert.
2. One of my favorite ochem labs.
3. Notes from my favorite ochem lecture taught by Dr. J.
OXIDIZERS!! What can we use to oxidize our alcohols? Some of the common oxidizing agents are listed here. Depending on the nature of the substrate, different oxidizing agents are available to oxidize the primary or secondary alcohol to aldehyde or carboxylic acid. Some of the oxidizers are relatively cheap and easy to obtain such as KMnO4 and PCC. Others are toxic or smelly such as the Swern.
What word does this peptide chain spell?
Let's do a deep dive into amino acid chemistry regarding their structure and reaction mechanisms.
If you swip right, you can see all the structure of the different amino acids for the genetic code.
Plus selenocysteine...? I don't know why it is included.
If you remember yesterday, I said that amino acids are kind of like DNA in that they have a backbone and side chains.
The backbone consists of two carbons, one with both an amine (-NH3) and the side chain, and one that is a carboxylic acid, both an alcohol group (-OH) and an aldehyde (=O). The chains can vary a lot.
Not enough for me to be able to differentiate between them mind you, still clueless at this whole biochemistry thing.
But! When presented with a nice graphic you can start to see all the interesting ways they are similar and different.
But how do they bind together to form peptides and proteins?
The peptide bond between amino acids is formed from a condensation reaction! Where the end product are two bound amino acids and, you guessed it, water!
I've drawn it out in the final picture.
First, the electron rich amine group off one amino acid attacks the carboxylic acid carbon from another.
It will specifically attack this carbon because of how electron withdrawing the oxygens off it it are.
This type of attack is known as a nucleophilic attack - an electron rich nucleophile (positive charge loving) group attacks a slightly positive electrophile (negative charge loving). But carbon can only have 8 electrons total, so it kicks two of its electrons to the double bonded oxygen, now a single bonded oxygen.
From here, the alcohol picks up the extra proton (off the amine) to make water, and the highly negative single bonded oxygen reforms its double bond.
Again, carbon can't have more than 8 electrons.
This time however, the water group is pretty self sufficient and makes for a great leaving group. So! It gets kicked off and we are left with our peptide bond and water!
Little ochem and mechanisms for you today!
Let's move on to the next type of nucleophilic substitution! The SN1 reaction proceeds stepwise and the first step is the biggest barrier of the reaction. The leaving group leaves first which results in the formation of a carbocation that is then attacked by a nucleophile. This type of reaction occurs readily with a substrate that can generate a tertiary carbocation because the stability of the carbocation is largely dependent on increasing substitution of the carbon.
Your whole team can mine data in a single repository avoiding redundant work and sloppy file versioning. You have full control on what data is private and what is shared with collaborators. 💪 .
Try us for 🎁 FREE! Clickable link in bio @cdd_vault for free a free trial, or visit www.collaborativedrug.com