Gives the corresponding tertiary alcohol.Įxamples that you will be taught in any organic chemistry reactivity course,īetween organic compounds can be explained by just using his principle of Giving an intermediate alkoxyde, which after treatment with a proton source (H +), Ketone releases this charge polarization on the electrophilic ketone (this is Nucleophilic addition of organometallic reagents to electrophilic ketones In this example, a negatively charged carbon atom of a Grignard reagent, such as PhMgBr (phenyl magnesium bromide), acts as a nucleophile. Typical nucleophiles for ketones are organic or organometallic reagents with high electron density. In this way, nucleophiles can react with electrophiles. How Does Charge Distribution Result on Reactivity Trends? This charge distribution, makes the carbon atom of the carbonyl group a potential electrophile that can react with different nucleophiles. This is a combination of induction and resonance effects.īut the result is clear: a partial negative charge (□-) is generated at the oxygen atom, and a partial positive charge (□-) is generated at the carbonyl carbon atom. Oxygen is more electronegative than carbon, so it wants to hold the electrons of the covalent bond more than carbon. In this molecule, a electronegative atom (O) is covalently attached to a carbon. This is a great example of how electronics work. This second partner, which has low electron density and wants electrons, is called electrophile.Ī scheme of the most typical electrophile in organic chemistry: a carbonyl In very simple terms: we say that a molecule behaves as a nucleophile if it has a functional group that has a lot of electrons (high electron density), and wants to attack another functional group that lacks electrons. Generally, two organic molecules react because one part (or functional group) of one of the molecules has with high electron density ( nucleophile) and another part of another molecule, has a low electron density ( electrophile). If you have studied anything about reactivity of organic molecules, you know that the movement of electrons rules everything. Basic Organic Chemistry: What are Electronic Effects? So, we will try to cover that gap on this article. I would say that most textbooks are missing a specific general overview about this (although you can argue that this is the entirety of basic organic chemistry itself). We will show different examples on how these two are used to rationalize chemistry, both independently or in combination. We will explain what this combination is about, going through the basics of what electronic and steric effects are. This combination is key for grasping the big picture of organic chemistry. However, we like to think about a combination of steric and electronic effects as a simplified version of this concept. Stereoelectronics is not a concept that, by itself, is usually taught in introductory courses (if you check the Wikipedia page on it, for example, it shows a significantly advanced discussion). This simple but important concepts are the basis of most rationalizations or models in organic chemistry.Įlectronic and steric effects are the basis of most organic chemistry models. More accesible electriphilic centers will be more reactive, due to steric effects. In very simple terms, nucleophiles attack electrophilic positions due to electronic effects. In a very simplefied fashion, you can argue that you can explain everything in organic chemistry by arguments of either “ electronic effects“, “ steric effects“, or a combination of the two. Keep reading! What Is the Most Important Concept to Grasp in Basic Organic Chemistry? However, there are key concepts, specifically the one(s) we will discuss here, that will help you see organic chemistry from a brighter side. You obviously also need a solid background on general chemistry.Īnd yeah, learning how to run a perfect TLC helps too! To do so, a good organic chemistry textbook and a nice molecular modeling kit are gonna be your best companions. In any case, you really need to be prepared. The learning process that your brain must follow for o-chem is very different. This makes complete sense, since organic chemistry is a very unique branch of science. You are not alone feeling like this subject is special. 15 Adding in Steric Effects to Basic Organic Chemistry What Are the Keys for Learning Organic Chemistry?
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