9.1 Organic Chemistry9.1 Organic Chemistry

A BRIEF HISTORY OF ORGANIC CHEMISTRYA BRIEF HISTORY OF ORGANIC CHEMISTRY

1780’s1780’s scientists began to distinguish between scientists began to distinguish between organicorganic and and

inorganicinorganic compounds compounds

organic compoundsorganic compounds -- were defined as compounds that were defined as compounds that could be obtained from living organismscould be obtained from living organisms

inorganic compoundsinorganic compounds -- came from non-living sourcescame from non-living sources

VitalismVitalism the intervention of a VITAL FORCE was needed to the intervention of a VITAL FORCE was needed to

synthesize organic compoundssynthesize organic compounds therefore such syntheses could only take place in living therefore such syntheses could only take place in living

organisms and could not take place in the test tubes organisms and could not take place in the test tubes and flasks of the laboratory.and flasks of the laboratory.

1828 - Fredrich Wöhler1828 - Fredrich Wöhler synthesized the organic compound urea (a constituent synthesized the organic compound urea (a constituent

of urine)of urine) urea was synthesized by evaporating an aqueous urea was synthesized by evaporating an aqueous

solution containing the inorganic compound ammonium solution containing the inorganic compound ammonium cyanatecyanate

OO

||||NHNH44

++NCONCO-- + heat + heat HH22N-C-NHN-C-NH22

ammonium cyanateammonium cyanate urea urea

1828 –18501828 –1850 a number of clearly organic substances were a number of clearly organic substances were

synthesized from sources that were clearly inorganicsynthesized from sources that were clearly inorganic Vitalism died slowly and did not completely disappear Vitalism died slowly and did not completely disappear

from scientific circles until 1850from scientific circles until 1850 August Kekule gave the science of organic chemistry August Kekule gave the science of organic chemistry

its modern definition…its modern definition…

MODERN MODERN ORGANIC CHEMISTRYORGANIC CHEMISTRY

ORGANIC CHEMISTRYORGANIC CHEMISTRY - the study of the - the study of the molecularmolecular compounds of compounds of carbon (C)carbon (C)

the properties of organic compounds are a result of the the properties of organic compounds are a result of the covalent bonds within their moleculescovalent bonds within their molecules

NOTE: The oxides of carbon as well as the compounds NOTE: The oxides of carbon as well as the compounds

of carbonate, bicarbonate, cyanide, cyanate and of carbonate, bicarbonate, cyanide, cyanate and thiocyanate ions are not considered organic compounds. thiocyanate ions are not considered organic compounds. InorganicInorganic compounds like these contain ionic bonds. compounds like these contain ionic bonds.

Which of the following are organic compounds?Which of the following are organic compounds?NONO22 COCO CuNOCuNO33 NaNa22COCO33 CC22HH55OH OH COCO22 KCNKCN CC66HH66 NaHCONaHCO33 CC22HH33ClCl33 NaSCNNaSCN CC33HH88

Organic Compounds and Our Daily LivesOrganic Compounds and Our Daily Lives More than More than 10,000,00010,000,000 compounds have been discovered compounds have been discovered

How many of these are organicHow many of these are organic? ? 9,000,0009,000,000 (90 %) (90 %) 250,000250,000 new organic compounds made in laboratories new organic compounds made in laboratories

each yeareach year

Chemists isolate and identify chemicals from natural products Chemists isolate and identify chemicals from natural products & then synthesize these or similar chemicals for various & then synthesize these or similar chemicals for various purposes.purposes.

Examples of Examples of syntheticallysynthetically produced chemicals are: produced chemicals are: Gasoline, solvents, polyester and nylon, synthetic Gasoline, solvents, polyester and nylon, synthetic

sweeteners, artificial flavors, medicinessweeteners, artificial flavors, medicines

Carbon compounds include: DNA, proteins, enzymes, wool, Carbon compounds include: DNA, proteins, enzymes, wool, cotton, rubber, plastics, organic pesticides, food additives, cotton, rubber, plastics, organic pesticides, food additives, Propellants for aerosolsPropellants for aerosols

CARBONCARBON How many valence electrons does carbon have? How many valence electrons does carbon have?

Atomic #6 – Atomic #6 – 66 total electrons; total electrons; 44 valence electrons valence electrons

Draw the Lewis electron dot diagram for carbon (p.269)Draw the Lewis electron dot diagram for carbon (p.269)

C C

What is the bonding capacity of carbon?What is the bonding capacity of carbon?

bonding capacitybonding capacity – – is the maximum number of single is the maximum number of single covalent bonds that an atom can form; determined by the covalent bonds that an atom can form; determined by the number of number of bonding electronsbonding electrons

Carbon has 4 bonding electrons & the capacity to form Carbon has 4 bonding electrons & the capacity to form 4 bonds4 bonds

most carbon compounds contain hydrogen. In most carbon compounds contain hydrogen. In addition they often contain oxygen, sulfur, addition they often contain oxygen, sulfur, phosphorus, nitrogen and or halogens (F, Cl, Br, I).phosphorus, nitrogen and or halogens (F, Cl, Br, I).

Activity: Find the bonding capacities of each of these atoms:Activity: Find the bonding capacities of each of these atoms:

# Valence e’s# Valence e’s # Bonding # Bonding e’se’s

CarbonCarbon

Nitrogen / PhosphorusNitrogen / Phosphorus

Oxygen / SulfurOxygen / Sulfur

Halogens (F / Cl / Br / I)Halogens (F / Cl / Br / I)

HydrogenHydrogen

See Table 8.3 p.274.See Table 8.3 p.274.

STRUCTURAL MODELS AND DIAGRAMSSTRUCTURAL MODELS AND DIAGRAMS

Using Using propane propane ((CC33HH88)) as an example: as an example:

1. Complete structural diagram1. Complete structural diagram - shows all atoms and bonds- shows all atoms and bonds

H H H H H H Ex: Ex: H-C-C-C-HH-C-C-C-H

H H H H H H

2. Condensed structural diagram2. Condensed structural diagram - omits the C-H bonds, but - omits the C-H bonds, but shows the C-C bondsshows the C-C bonds

Ex: Ex: CHCH33-CH-CH22-CH-CH33

3. Line structural diagram3. Line structural diagram - each line represents a bond - each line represents a bond between between 2 C atoms and H atoms are not shown2 C atoms and H atoms are not shown

Ex:Ex:

Isomers of Organic CompoundsIsomers of Organic Compounds

STRUCTURAL ISOMERSSTRUCTURAL ISOMERS - are different compounds - are different compounds that have the same molecular formula, but differ in the that have the same molecular formula, but differ in the order in which their atoms are bonded together order in which their atoms are bonded together

Chemists use models and diagrams to represent Chemists use models and diagrams to represent different isomers, because molecular formulas do not different isomers, because molecular formulas do not specify the isomer being consideredspecify the isomer being considered

Activity: Draw a complete, condensed and a line Activity: Draw a complete, condensed and a line structural diagram for all possible isomers of Cstructural diagram for all possible isomers of C33HH77Cl…Cl…

AssignmentAssignment

1. Q. 1-4 p.291. 1. Q. 1-4 p.291.

We will be doing Investigation 9.1 tomorrow We will be doing Investigation 9.1 tomorrow using molecular model kits.using molecular model kits.

Families of Organic CompoundsFamilies of Organic Compounds Chemists classify organic chemicals into families based Chemists classify organic chemicals into families based

on the characteristic structures and bonds believed to on the characteristic structures and bonds believed to exist within the molecules.exist within the molecules.

A Functional GroupA Functional Group is the part of the molecule where is the part of the molecule where most of its chemical reactions take place; the part of the most of its chemical reactions take place; the part of the molecule that effectively determines the chemical (and molecule that effectively determines the chemical (and some physical) properties of the compoundsome physical) properties of the compound

Almost all organic molecules contain C-C and C-H bonds Almost all organic molecules contain C-C and C-H bonds which are much less reactive than common functional which are much less reactive than common functional groups groups

Consider ethanol:Consider ethanol: CHCH33-CH-CH22-OH-OH

Ethanol’s chemical and physical properties are Ethanol’s chemical and physical properties are largely determined by the presence oflargely determined by the presence of thethe –OH –OH group known as the group known as the hydroxyl grouphydroxyl group

See Table 23.1, page 726 See Table 23.1, page 726 *Note:*Note: “ “R”R” represents any chain of carbon and represents any chain of carbon and

hydrogen atoms hydrogen atoms ““R(H)” indicates that the branch may R(H)” indicates that the branch may

be a carbon be a carbon chain or a single H chain or a single H atomatom

“ “X”X” represents a halogen atom (group 17) represents a halogen atom (group 17)