ORGANIC CHEMISTRY Chapter 1 Organic Compounds 1 1

ORGANIC CHEMISTRY

Chapter 1: Organic Compounds (1. 1) An Introduction

What is Organic Chemistry? l l l 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 B 12

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

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

Functional Groups l Elements or groups bound to organic compounds are called functional groups. l 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.