Organic Chemistry Basics For Pre-Meds

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Organic Chemistry Basics for the Pre-Med

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Organic Chemistry Destroys Pre-Meds

Not beating around the bush here. Organic Chemistry(aka Orgo) destroys more pre-meds then any other class. If you underestimate it or go in unprepared you will pay for it. However, with that being said, Orgo is not an impossible class. Heck, in some ways it’s a lot easier then biology or chemistry. You just need to approach the content the right way. Set yourself apart, work hard, and you may find orgo gives you a nice boost to your sGPA. 

Organic Chemistry Study Strategies

Make sure you go into the class with the right attitude and the right strategy. Here are some tips to help you do that.

  1. Always be 1 day ahead of the class. (That means review the material before class!) 
  2. Sign up for tutoring starting on day 1.
  3. Learn the concepts!
  4. Practice, practice, practice.
  5.  Identify your weaknesses early!
  6. Set SMART Goals for yourself before the class begins and then refine those goals when you get your syllabus. 
  7. Hold yourself accountable.
  8. Be kind to yourself, especially if you are trying your hardest.
  9. Set aside time to study every day, even if it’s just review.
  10. Think of Organic Chemistry Like Chemistry in Motion
    1. A lot of your exams are going to focus on reactions. Reactions are like a little dance the molecules are doing. They will be pushed and pulled in different directions based on the rules of the dance. 
  11. Mechanisms, mechanisms, mechanisms.
    1. Forget memorization, you want to learn mechanisms. The mechanisms are what will be heavily tested on the exam, and they will save you or sink you on exam day. 
  12. Go Above and Beyond and You’ll Be Rewarded on Test Day.
    1. Doing your readings, labs, homework and assignments is just the very basic requirements for the class. To get an A, seek out additional study materials like ‘Organic Chemistry as a Second Language’ or Masterorganicchemistry.com
  13. Ask Peers, Upper Classmates, and Even the Teachers Themselves For Advice.
    1. Always get advice from people who have already taken the exams. Even better, ask your teacher for advice on the best ways to prepare for their exams. They know how the exam will be laid out and how to go about studying properly for it.
  14.  Become Better then the Class.
    1. Find harder problems online. Google Organic Chemistry Test Problems with Answers. If you can answer harder problems then the ones you’re given in class, then test day won’t be a challenge – it’ll be a break. 

Our Approach to Organic Chemistry Basics

This is a tougher class to review basics. So what we’re going to do is identify 5 High Yield Topics and briefly cover them. Then at the end we’ll point you towards 5 High Yield Resources. Read this to give you an idea of what you’re in store for, learn the study tips we give above, and then when you finally take organic chemistry hit up the high yield resources for additional help. 

Formal Charge

One of the first things you need to understand how to do is calculate a formal charge. Fortunately, there’s a handy formula for that!

Formal Charge = (# of valence electrons on the atom) – (non-bound electrons + number of bonds)

Example: :CH3
Carbon has 4 valence electrons.
Carbon here has one pair (2) of non-bound electrons (a single lone pair).
Carbon has 3 bonds to Hydrogen around it.

So let’s do the math (4) – (2+3) = -1


Why is this important?

It helps you track and predict the reactivity of a molecule. All of the work in organic chemistry comes down to motion. Think about the transformer toys. The robots that turn into vehicles. There’s a series of steps to go from robot to truck and back again. Organic chemistry mechanisms work in a similar way. 

Pushing and Pulling: Moving Electrons

Source: MasterOrganicChemistry.com. If you really wanted to learn Orgo. Go to this site!

This image is from masterorganicchemistry.com and shows a very simple example of a typical organic chemistry reaction. Astute observers will notice two arrows. A curved arrow and a straight arrow. One way to think about this is the order in which it happens. You have a curved arrow, in this case oxygen is pulling that pair of electrons to itself. Then you have the straight arrow pointing to what it looks like next. 

Note how the tail of the curved arrow is coming from the bond, and not the H or the O.
Note how the head of the curved arrow is pointing to exactly where the electrons are going. 
Finally, note how there’s a charge OH and the H?

For Bonus Practice Points, calculate the formal charge on the OH-!

Functional Groups

Above are some key functional groups that you’ll be encountering in your class. Being able to identify and name the functional groups are really important.

Also being able to name it based on hierarchy is also important! What does it mean to name based on hierarchy? Well if one compound has two functional groups, it’s name is based on the functional group with the top hierarchy. To read more about hierarchies, check out this great post by MasterOrganicChemistry.com

Substitution, Elimination, & Addition Reactions

Despite the names, math will not help you here. All of these reactions require you to identify neutrophiles and electrophiles. Consider the electrophile the prey and the neutrophile as the predator. Electrophiles are also called substrates.

Substitutions

A substitution takes place when a neutrophile attacks an electrophile and replaces it. Hence the term, ‘substitution’.

Image from UCLA Chemistry and Biochemistry

Of course there’s a lot more that goes into this. There’s actually 4 factors that go into determining the elimination reaction. 

  1. The Electrophile (The Prey)
  2. The Nucleophile (The Predator)
  3. The Leaving Group
  4. The Solvent
We’re not going to into how each of these factors contribute to the reaction. We’ll just say that you do need to consider all 4 when determining if a reaction is favorable or not. If you can get down substitution reactions, including SN1 and SN2 reactions, you’ll be ready for a ton of the reactions you’ll see on exams. 

Eliminations

Source: Wikipedia

So with substitution reactions we had a neutrophile swoop in and replace the electrophile. In elimination reactions there’s no replacement. The reaction simply causes the functional group to get ‘bumped off’ and replaced with a double bond. The reaction in the picture above is a good example of a  slightly more complicated reaction. Here’s a tremendous resource for learning about elimination reactions. 

High Yield Resources

The Path to Medical School Can Feel Long And Unclear

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