Drawing Enantiomers

Dr. Hoeger’s UCSD Pre-Lecture: O-Chem 2

I like that Professor Carl Hoeger:

a) was able to effectively recap in 2 sentences everything my previous O-chem teachers tried to explain in three months

b) says “damn” during his lecture

Check it out here:

http://podcast.ucsd.edu/podcasts/rss.aspx?podcastId=622&v=1

Best NMR Tutorial Ever

GO HERE:

http://www.wfu.edu/~ylwong/nmr/

 

 

And look! You can even do a drag & drop exercise!!! *drool*

Infrared: Fingerprint Region

Breakdown of the IR region is as follows:

• Functional Group (4000-1500 cm^-1)
• Fingerprint Group (1500-900 cm^-1)
• Aromatic (although this is better seen through NMR)

IR fingerprint region. You can't see the aromatic region which is all the way to the right.

On this entry, we’re concerned about the fingerprint region.

The fingerprint region (1500-900 cm^-1) lies between the functional and aromatic regions.

This place is rife with a bunch of complex bands due to the bending vibrations that occur here. NMR now predominates the analysis of this region but the significance of the C-O bond (1300-1000 cm^-1) carries some importance here.

“Because the C-O bonds are highly polarized, their absorption bands are generally very strong (254).” But be careful since esters, ethers, and alcohols dwell around this region, too.  If you see something in the middle of this region you can bet that a single bonded carbon-oxygen will show up in your molecule.

Mutarotation

Note: This is not required for the MCAT

If you put sucrose in water, its optical properties change. It mutates. Sounds frighteningly boring because it is.

Luckily it doesn’t happen for all sugars. Just the ones where the anomeric carbon is a hemiketal or hemiacetal. Didja get that? You can check out wikipedia for this.

3-Dimensional Structure of Proteins

♪Note:  Only 1° and 2° structures are required for proteins on the MCAT

Proteins make up your body. These are what proteins look like.

Primary structure

The order of polypeptides fall under the primary structure.

The primary structure is like the order of letters in a very long word…However, the precise primary structure of a protein is determined not by the random linking of amino acids, but by inherited genetic information (82)

Secondary structure

This involves the twisting of strands and the pleating of β sheets.

Ion Exchange Chromatography

Helps you find the difference between the amino acids by sifting through a resin. If you used a cation exchange resin in which the positively charged cation is exposed:

1. The most negative travels the fastest
2. The least polar travels the slowest

Partially Hydrolizing Peptides

Enzymes cut in certain places only.

Titration of Glycine

Think back to general chemistry. What, you forgot it? Oh well, so did everyone else.

Amino Acids: Acid & Bases

Dude, just accept it. Chemistry is all about acids and bases.