Archive for the "Organic Chemistry Reactions" Category

Organic Chemistry Reactions blog archives will get you quick tips on organic chemistry reactions for your examinations ahead. Organic chemistry reactions were never easy before StudyOrgo.com came online.

The SN2 Reaction

Posted on August 31st, 2015

The start of first semester organic chemistry can be an information overload.  For the first few classes, you will review general chemistry concepts and then… the reactions start coming!  One of the first reactions that will be covered is the SN2 reaction, mainly because it is relatively straight forward and a good tutorial for how to describe reaction mechanisms.  In this article, we will review the important topics of an SN2 reaction.  Sign up with StudyOrgo today to get detailed reaction mechanisms and explanations to stay on top of your class!

Alkyl halides as SN2 substrates

One of the most reactive molecules involving substitution reactions are alkyl halides.  However, there are a number of considerations to keep in mind to determine if the SN2 mechanism describes your reaction. First, let’s look at a simple SN2 reaction; methyl chloride and NaOH to form methanol and NaCl.

sn2 figure 1

Let’s break down the reaction mechanism into the basic elements.  An SN2 reaction gives you 3 pieces of information, first the ‘S’ indicating ‘substitution’, the ‘N’ denoting the reaction involves a nucleophile and ‘2’ describing the process as bimolecular – meaning both the substrate and the nucleophile determine the rate of the reaction.  The hydroxide will attack the carbon center and form a new bond with carbon (which makes it the nucleophile) and the chlorine atom will leave the carbon center with the electrons from the C-Cl bond (which makes it the leaving group).

Inductive effects of leaving groups: Chloride is a good leaving group because of the inductive effects (or electron withdrawing potential) of the halogen atom.  This is the characteristic of good leaving groups.  The electronegativity of chlorine makes the carbon center slightly electrophilic, meaning it has a partial positive charge, which is strongly attracted to electron-rich nucleophiles.

sn2 figure 2

Strong bases as a nucleophile: In order to form a new bond with carbon, a good nucleophile has to be electron rich.  The strong basic properties of NaOH make the charge on oxygen negative, and thus a good nucleophile.  Likewise, the poor basic properties of Cl anion make it an excellent leaving group.  Below is a chart to help illustrate the contrasting properties of nucleophiles and leaving groups.

sn2 figure 3

Inversion of stereochemistry due to geometry of attack: Once the nucleophile attacks the carbon center, a partial formation of C-O bond and breaking of C-Cl bond occurs in a concerted (or instantaneous) fashion, depicted below.  Because the angle of attack for the nucleophile has to be opposite of the leaving group, the OH adds to the opposite side of the carbon center, causing an inversion of stereochemistry.  This is an important clue in determining if reactions occur using the SN2 mechanism.

sn2 figure 4

Preparing for Organic Chemistry This Fall

Posted on August 5th, 2015

One of the questions we are repeatedly asked at StudyOrgo is “how do I to get ahead in organic chemistry this fall semester?” Many of you have heard that organic chemistry is a brutal class that does little but to depress your GPA. While it is true that this course is challenging, we here at StudyOrgo are devoted to helping you get the “A” you deserve!

Organic chemistry gets a bad name because it assumes that you are experts with regards to all of the general chemistry from freshman year, and you are now responsible to know it!  As an analogy, think of your chemistry courses as a pyramid to reaching your degree goals.  Organic chemistry is directly placed in the middle of the pyramid, it will be very important not only for the MCAT or DAT exams, but also for future advanced courses.  Organic chemistry is supported by General Chemistry, which is why you took it last year.  Fortunately, StudyOrgo is placed in the center of your pyramid base and we are here to help all of your organic chemistry questions.  Our simple and clear-cut explanations of reaction mechanisms and concepts will easily help you with anything you might struggle with this semester.  Here are a few tips on how to prepare today for the course this Fall.

chemistry pyramid

  • Open your text book –Read the title and abstract on the first page of each chapter and check out the number of pages. It will give you a very quick idea of what you will be learning about in each chapter and how much material you will be covering.
  • Look at a syllabus – Remember, your syllabus is an official contract between you and the professor. They must disclose what you are required to learn and how you will be graded. Professors can remove requirements but cannot easily add them. Use this to your advantage! Highlight the contents or reactions of the book that will be required and use this to focus your attention on while studying over the semester.
  • Schedule your studying! – Now that you know where the book is and a rough idea of what you are responsible for learning from the syllabus, take a calendar and divide the time you have to each test by the number of chapters. Schedule 2-3 hours a week to study and DON’T SKIP OR RESCHEDULE. Think of it as a doctor or dentist appointment – you just have to do it! Also, if you plan your studying ahead, you will be less likely to schedule something that gets in the way because you will already have penciled it in! Use your Smartphone calendar to send you alerts and reminders for your studying appointment.
  • Read ahead – If you have time this summer, read at least two chapters to get yourself ahead of the class. Don’t try to understand everything, just pay attention to the words used and the ideas. This will allow you to pay more attention and ask questions about the details in class instead of scrambling to write down notes and drawings.
  • Sign up with StudyOrgo – The Editors at StudyOrgo have spent numerous hours reviewing and preparing the material in the most crystal-clear and “get-to-the-point” manner as possible. We consult students and ask for their opinion on whether they understand the material as presented. We provide quick descriptions and in-depth mechanism explanations. Many of our reaction have multiple examples, so you can learn and then quiz yourself in our website! For the student on-the-go, we have also developed a mobile app (iOS and Android) provides all the functionality of the website! All of these benefits are included in your StudyOrgo membership!

With a little time management and help from StudyOrgo, you will have no trouble getting an “A” in Organic Chemistry this year!

Allylic Halogenation 2 Video Tutorial

Posted on March 20th, 2015

Here is a look at a video tutorial that we include with the reactions to help you learn them backwards and forwards.

 

Acetal Formation

Posted on December 12th, 2014

Intermolecular Acid-Catalyzed Acetal Formation

Ketone + diol → Acetal

Overall Big Picture: This reaction forms a hemiacetal from an aldehyde or ketone and a diol and further reacts to form the acetal group.

Key Tip: In the presence of alcohols under acidic conditions, carbonyls can be reduced to acetals.

Full reaction description including our proven flash card method and mechanism is available for members only.  Join here…