Organic Chemistry Dr. Michael P. Gillespie. Introduction Organic chemistry is the study of carbon containing compounds. It was once thought that all organic

Organic Chemistry

Dr. Michael P. Gillespie

Introduction

• Organic chemistry is the study of carbon containing compounds.

• It was once thought that all organic compounds, such as fats, sugars, coal, and petroleum, were formed by living or once living organisms.

• Friedrich Wohler synthesized the organic molecule urea from inorganic starting materials.

• He is considered the “father or organic chemistry”.

2Dr. Michael P. Gillespie

Friedrich Wohler

Dr. Michael P. Gillespie 3

The Chemistry of Carbon

• Carbon can form stable, covalent bonds with other carbon atoms.

• Atoms can form stable bonds with other elements.

• Carbon can form double or triple bonds with other carbon atoms.


Allotropes

• Allotropes are forms of an element that have the same physical state, but different properties.

• Graphite, diamond, and buckminsterfullerine are three allotropic forms of carbon.


Allotropes


Buckminsterfullerine


Buckminster Fuller


Organic Vs. Inorganic

Compounds• The bonds between carbon and other

atoms are almost always covalent bonds, whereas the bonds in many inorganic compounds are ionic bonds.

• This accounts for many of the differences observed between organic and inorganic compounds.


Organic Vs. Inorganic

Compounds• Ionic bonds result from the transfer of

one or more electrons from one atom to another. Ionic bonds are electrostatic.

• Covalent bonds result from the sharing of one or more pairs of electrons.


Organic Vs. Inorganic Compounds

• Ionic compounds often form three-dimensional crystals made up of many positive and negative ions.

• Covalent compounds exists as individual units called molecules.

• Water-soluble ionic compounds dissociate in water to form electrolytes.

• Most covalent compounds are non-electrolytes.


Inorganic Compounds

• Ionic substances have much higher melting and boiling points than covalent compounds.

• Ionic substances are more likely to dissolve in water than in a less polar solvent.


Organic Compounds

• Organic compounds are typically non-polar or moderately polar.

• They are less soluble or non-soluble in water.


Families of Organic

Compounds• Organic compounds

• Hydrocarbons – a molecule which contains only carbon and hydrogen.

• Substituted hydrocarbons – a molecule in which one or more of the hydrogen atoms is replaced by another atom or group of atoms.


Families of Organic Compounds

• Organic Compounds• Hydrocarbons

• Aliphatic hydrocarbons• Alkanes• Cycloalkanes• Alkenes• alkynes

• Aromatic hydrocarbons

• Substituted hydrocarbons


Functional Group

• A functional group is an atom or a group of atoms arranged in a particular way that is primarily responsible for the chemical and physical properties of the molecule in which it is found.


Alkanes

• Alkanes are saturated hydrocarbons.

• They are hydrocarbons that have only carbon and hydrogen atoms that are bonded together by carbon-carbon and carbon-hydrogen single bonds.

• Non-polar, water insoluble, with low melting and boiling points.


Constitutional or Structural Isomers

• Constitutional and structural isomers of alkanes exist.

• These isomers have the same structural formula but different structures.

• The atoms are bonded to one another in different patterns.

• This gives the molecules different physical and chemical properties.


Cycloalkanes

• Cycloalkanes are a family of organic molecules that have C-C single bonds in a ring structure.

• They are names by adding the prefix cyclo- to the name of the parent alkane.

• Stereoisomers exist of these molecules.


Cis-trans Isomerism

• A cis-trans isomer is a type of stereoisomer.

• Stereoisomers are molecules that have the same structural formula and bonding pattern but different arrangements of atoms in space.

• A cycloalkane is in the cis configuration if two substituents are on the same side of the ring (either above or below). It is in the trans configuration when one substituent is above the ring and the other is below.


Conformations of Alkanes and Cycloalkanes

• Free rotation exists around the carbon-carbon single bonds; therefore, many conformations or conformers exist for any alkane.

• Cycloalkanes also allow for limited rotation around their carbon-carbon single bonds. This allows for a variety of conformations.


Cyclohexane Conformations


Documents

Organic Chemistry Dr. Michael P. Gillespie. Introduction Organic chemistry is the study of carbon containing compounds. It was once thought that all organic