Organic Chemistry

• Organic chemistry was first defined as a branch of modern science in 1806 by Jon Jacob Berzelius
• Berzelius classified chemical compounds into two groups: organic if they originated in living or once-living matter, and inorganic if they came from "mineral" or non-living matter
• In 1828, Frederich Wöhler discovered that urea, an organic compound, could be made by heating ammonium cyanate, an inorganic compound
• Wöhler's discovery of urea represented the abandonment of Vitalism as a scientific theory
• Wöhler's discovery also represented the discovery of isomerism - the possibility of two or more different structures based on the same chemical formula
• By the 1860s, chemists like Friedrich August Kékulé were proposing theories on the relationship between a compound's chemical formula and the physical distribution of its atoms
• Chemists in the 1900s were trying to determine the nature of chemical bonding by developing models for electron distribution
• During the 20th century, organic chemistry branched into sub-disciplines such as polymer chemistry, pharmacology, bioengineering, petrochemistry, and numerous others
• Today, over 98% of all known compounds are organic
• There are three generally accepted sources of organic compounds: carbonized organic matter, living organisms, and invention/human ingenuity
• Coal, oil, and natural gas are examples of carbonized organic matter
• Fossil fuels like coal, oil, and natural gas have been utilized on a large scale for over 300 years
• Organic compounds extracted from living organisms include penicillin, acetylsalicylic acid (aspirin), vanilla flavoring, and digitalis
• Antibiotics, aspirin, vanilla flavoring, and heart drugs are examples of substances that are manufactured in laboratories from organic starting materials
• Over 250,000 new chemical compounds are discovered each year
• Organic compounds are flammable and react readily with oxygen
• Most organic compounds are insoluble in water and soluble in non-polar organic solvents
• Organic compounds are nonelectrolytes and do not conduct electricity
• Organic compounds have low boiling and melting points, with many being gases, liquids, or solids with low melting points
• Organic compounds have a high vapor pressure, with some undergoing sublimation
• Organic compounds exhibit isomerism, where compounds have the same molecular formula but different structures
• Organic chemistry is the study of compounds that contain the element carbon
• Biochemistry, food, fuel, plastics, natural and synthetic fibers, drugs and medicine, hygiene and beauty products, agricultural chemicals, and colorants are all significant applications of organic compounds in life and civilizations
• Carbon is the only element whose atoms can bond together to form long straight chains, branched chains, and intricate ring structures
• Organic compounds contain carbon atoms and most contain hydrogen atoms
• Carbon forms single, double, and triple bonds to other carbon atoms
• Organic compounds may also contain elements other than carbon and hydrogen, known as heteroatoms
• The most common multiple bond between carbon and a heteroatom is a carbon-oxygen double bond
• Shapes of organic molecules are determined by the VSEPR theory, with different arrangements based on the number of groups surrounding an atom
• Drawing organic molecules can be done using condensed structures
• In a condensed structure, all atoms are drawn in, but two-electron bond lines and lone pairs on heteroatoms are generally omitted
• A carbon bonded to 3 H's becomes CH3
• A carbon bonded to 2 H's becomes CH2
• A carbon bonded to 1 H becomes CH
• When drawing a skeletal structure, assume there is a carbon atom at the junction of any two lines or at the end of any line
• Valence bond theory describes a covalent bond as the overlap of half-filled atomic orbitals on different atoms, each containing a single electron
• A covalent bond forms when an orbital on one atom overlaps an orbital on a second atom and the single electrons in each orbital combine to form an electron pair
• Sigma bonds can be formed from head-to-head overlaps of atomic orbitals, such as two s orbitals overlapping to form one big lobe (as in H2)
• A π bond is a type of covalent bond that results from the side-by-side overlap of two p orbitals
• All single bonds are σ bonds, while multiple bonds consist of both σ and π bonds