9.1 Organic Chemistry

A BRIEF HISTORY OF ORGANIC CHEMISTRY scientists began to distinguish between organic and inorganic compounds organic compounds - were defined as compounds that could be obtained from living organisms inorganic compounds - came from non-living sources Vitalism the intervention of a VITAL FORCE was needed to synthesize organic compounds therefore such syntheses could only take place in living organisms and could not take place in the test tubes and flasks of the laboratory.

synthesized the organic compound urea (a constituent of urine) 1828 - Fredrich Wöhler synthesized the organic compound urea (a constituent of urine) urea was synthesized by evaporating an aqueous solution containing the inorganic compound ammonium cyanate O || NH4+NCO- + heat H2N-C-NH2 ammonium cyanate urea 1828 –1850 a number of clearly organic substances were synthesized from sources that were clearly inorganic Vitalism died slowly and did not completely disappear from scientific circles until 1850 August Kekule gave the science of organic chemistry its modern definition…

MODERN ORGANIC CHEMISTRY ORGANIC CHEMISTRY - the study of the molecular compounds of carbon (C) the properties of organic compounds are a result of the covalent bonds within their molecules NOTE: The oxides of carbon as well as the compounds of carbonate, bicarbonate, cyanide, cyanate and thiocyanate ions are not considered organic compounds. Inorganic compounds like these contain ionic bonds. Which of the following are organic compounds? NO2 CO CuNO3 Na2CO3 C2H5OH CO2 KCN C6H6 NaHCO3 C2H3Cl3 NaSCN C3H8

Organic Compounds and Our Daily Lives More than 10,000,000 compounds have been discovered How many of these are organic? 9,000,000 (90 %) 250,000 new organic compounds made in laboratories each year Chemists isolate and identify chemicals from natural products & then synthesize these or similar chemicals for various purposes. Examples of synthetically produced chemicals are: Gasoline, solvents, polyester and nylon, synthetic sweeteners, artificial flavors, medicines Carbon compounds include: DNA, proteins, enzymes, wool, cotton, rubber, plastics, organic pesticides, food additives, Propellants for aerosols

CARBON Atomic #6 – 6 total electrons; 4 valence electrons How many valence electrons does carbon have? Atomic #6 – 6 total electrons; 4 valence electrons Draw the Lewis electron dot diagram for carbon (p.269)   C  What is the bonding capacity of carbon? bonding capacity – is the maximum number of single covalent bonds that an atom can form; determined by the number of bonding electrons Carbon has 4 bonding electrons & the capacity to form 4 bonds

most carbon compounds contain hydrogen most carbon compounds contain hydrogen. In addition they often contain oxygen, sulfur, phosphorus, nitrogen and or halogens (F, Cl, Br, I). Activity: Find the bonding capacities of each of these atoms: # Valence e’s # Bonding e’s Carbon Nitrogen / Phosphorus Oxygen / Sulfur Halogens (F / Cl / Br / I) Hydrogen See Table 8.3 p.274.

STRUCTURAL MODELS AND DIAGRAMS Using propane (C3H8) as an example: 1. Complete structural diagram - shows all atoms and bonds H H H Ex: H-C-C-C-H 2. Condensed structural diagram - omits the C-H bonds, but shows the C-C bonds Ex: CH3-CH2-CH3 3. Line structural diagram - each line represents a bond between 2 C atoms and H atoms are not shown Ex:

Isomers of Organic Compounds STRUCTURAL ISOMERS - are different compounds that have the same molecular formula, but differ in the order in which their atoms are bonded together Chemists use models and diagrams to represent different isomers, because molecular formulas do not specify the isomer being considered Activity: Draw a complete, condensed and a line structural diagram for all possible isomers of C3H7Cl…

Assignment 1. Q. 1-4 p.291. We will be doing Investigation 9.1 tomorrow using molecular model kits.

Families of Organic Compounds Chemists classify organic chemicals into families based on the characteristic structures and bonds believed to exist within the molecules. A Functional Group is the part of the molecule where most of its chemical reactions take place; the part of the molecule that effectively determines the chemical (and some physical) properties of the compound Almost all organic molecules contain C-C and C-H bonds which are much less reactive than common functional groups

Consider ethanol: CH3-CH2-OH Ethanol’s chemical and physical properties are largely determined by the presence of the –OH group known as the hydroxyl group See Table 23.1, page 726 *Note: “R” represents any chain of carbon and hydrogen atoms “R(H)” indicates that the branch may be a carbon chain or a single H atom “X” represents a halogen atom (group 17)