ORGANIC CHEMISTRY

Chapter 1:Organic Compounds (1.1) An Introduction

What is Organic Chemistry? The study of hydrocarbons (carbon based compounds, where carbon is the principle element). Organic compounds occur naturally but they can also be synthesized in a laboratory. Organic compounds are present in living organisms such as plants, animals and fossil fuels. ex. Sugars, Vitamin B12

Carbon’s Properties Carbon can form 4 bonds due to its 4 valence electrons bond with itself to form chains, rings, spheres, sheets and tubes (which can be any size) form combinations of single, double and triple covalent bonds

Organic Families Although carbon is the principle element in organic compounds, other elements may be present as well. Since these compounds are so diverse, we categorize them into organic families. Organic families share similar physical properties (ex. melting point, boiling point, solubility, etc) and similar chemical properties.

Functional Groups Elements or groups bound to organic compounds are called functional groups. Functional groups determine if the molecule: has high or low melting & boiling points is polar or non-polar is reactive or non-reactive.

Functional Groups 3 Main Types of Bonds 1. Multiple bonds between C atoms ex. Single (C-C), double (C=C), and triple bonds (CC) These bonds are covalent bonds. Single covalent bonds between carbon atoms are strong, and therefore unreactive. Double and triple bonds between carbon atoms are weaker, and therefore reactive.

Functional Groups 2. Carbon atom bonded with a more electronegative atom. ex. O, N, halogen These bonds are always polar, due to the electronegativity differences (ΔEN). (C has partial +ve charge, atom that’s more electronegative has partial –ve charge). This difference in electronegativity means that the more electronegative atoms has a tighter hold on the electrons.

Functional Groups Increasing polarity of a molecule results in increasing attractions between molecules. Since the force between molecules has increased, the melting point/boiling point becomes higher as its harder to break molecules apart This electronegativity difference also allows for Hydrogen bonding to this high electronegative atoms (such as O and N), creating C-OH or C-NH bonds.

Functional Groups 3. Double bonded carbon and oxygen Carbon atom double bonded to an oxygen atom (C=O). This means that 4 electrons are being shared between these two elements. Since O is more electronegative, electrons are more closely held to the O atom  increases polarity of the molecule  which causes increased melting/boiling points.