Introduction to Organic Chemistry Bettelheim, Brown, Campbell and Farrell Chapter 10.
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Transcript of Introduction to Organic Chemistry Bettelheim, Brown, Campbell and Farrell Chapter 10.
Introduction to Organic Chemistry
Bettelheim, Brown, Campbell and Farrell
Chapter 10
Organic ChemistryCompounds that contain carbon– Other elements: H, O, N, Cl, F, Br, I, P, S
Most compounds known are organic (> 85 %)
NOT just from living systems (biochemistry)• Wohler synthesized urea from inorganic compounds• Vital Force Theory disprove
NH4Cl AgNCO H2N-C-NH2
OAgCl+ heat +
Ammoniumchloride
Silvercyanate
Urea Silverchloride
Biochemistry: Chemistry of Living Systems
• Biochemical MoleculesBiochemical Molecules– Carbohydrates – Lipids – Proteins and enzymes – Nucleic acids – Hormones– Vitamins– Almost all chemicals in living systems are organic
compounds
• Biochemical molecules are BIG organic molecules
Organic vs. Inorganic Compounds
Organic Compounds Inorganic Compounds
Bonding is almost entirely covalentMay be gases, liquids, or solidswith low melting points (lessthan 360°C)Most are insoluble in waterMost are soluble in organic solventssuch as diethyl ether, toluene, and dichloromethaneAqueous solutions do notconduct electricityAlmost all burn
Reactions are usually slow
Most have ionic bondsMost are solids with high melting points
Many are soluble in waterAlmost all are insoluble in organic solvents
Aqueous solutions conductelectricityVery few burn
Reactions are often very fast
Table 11.1
Organic Structures & Formulas
Molecular Formula: Molecular Formula: shows only the number of each type of atom
Structural Formula:Structural Formula: shows atoms and the bonds that connect them
Lewis Structure: Lewis Structure: shows the atoms, bonds and unshared electron pairs (valence electrons only)
Organic Compounds—Atoms & Bonds
• For neutral (uncharged) organic compounds– carbon: carbon: four covalent bonds and no unshared pairs of
electrons– hydrogen:hydrogen: one covalent bond and no unshared pairs
of electrons– nitrogen:nitrogen: three covalent bonds and one unshared pair
of electrons– oxygen:oxygen: two covalent bonds and two unshared pairs
of electrons– a halogen:a halogen: one covalent bond and three unshared
pairs of electrons
Number of bonds formed
Carbon 4 bonds
Nitrogen 3 bonds
Oxygen 2 bonds
Hydrogen 1 bond
Halogen 1 bond
Organic StructureVSEPR model:VSEPR model: the most common bond angles
are 109.5°, 120°, and 180°
H-C-C-H
H
H H
H H
HC C
H
HH-C C-H
H-C-O-H
H
H
HC O
HH-C-N-HH
HH
HN
H HC
H-C-C-Cl
H
H H
H
Ethane(bond angles
109.5°)
Ethylene(bond angles
120°)
Acetylene(bond angles
180°)
Methanol(bond angles
109.5°)
Formaldehyde(bond angles
120°)
Methanamine(bond angles
109.5°)
Methyleneimine(bond angles 120°)
Chloroethane(bond angles
109.5°)
::
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:
Organic Chemistry
• Chemistry of compounds containing C– Over 95% of known compounds are organic
• What makes C special?– Forms stable bonds with other C atoms
• Can form bonds to up to 4 other atoms• Can form chains, rings, many shapes
– Can form stable bonds with H, O, N, F, Cl, Br, I
Bonding of Carbon
• C has 4 valence electrons
• Would expect 2 s and 2 p electrons
• Actually see 4 “equivalent” bonds for tetrahedral C
• Explained by “hybrid orbitals”
Methane – Tetrahedral geometry
s and p Orbitals
• Orbitals have definite shapes and orientations in space
(insert Fig 2.11 of text)
(if it will not all fit on one screen, put part (a) on one screen and part (b) on the next)
Hybrid Orbitals—s and p combinationsHybrid Orbitals—s and p combinations
Functional Groups• Part of an organic molecule that undergoes
chemical reaction– “Business end” of molecule
• Functional groups are important – Undergo the same types of chemical reactions no
matter in which molecule they are found– Determine chemical and physical properties of
compound– Basis for organizing organic compounds into families– Used in naming organic compounds
Some Important Functional Groups
-OH
-NH2
-C-HO
-C-O
CH3CH2OH
CH3CH2NH2
CH3CHO
CH3CCH3
O
CH3COHO
-C-OHO
Example
Alcohol
Amine
Aldehyde
Ketone
Carboxylic acid
Ethanol
Ethanamine
Ethanal
Acetone
Acetic acid
NameFamilyFunctionalgroup
Alcohols• Alcohol:Alcohol: contains an OH (hydroxyl) group
bonded to a tetrahedral carbon atom
– may be primary (1°), secondary (2°), or tertiary (3°)
CH3-C-OH
H
HCH3-C-OH
CH3
HCH3-C-OH
CH3
CH3
A 1° alcohol A 3° alcoholA 2° alcohol
R-C-O-HR
RCH3CH2OH
H
HH
HH-C-C-O-H
Structuralformula
Functional group(R = H or carbon
goup
Condensedstructuralformula
::
Amines• Amine:Amine: a compound containing an amino amino
groupgroup– the amino group may be primary (1°),
secondary (2°), or tertiary (3°)
CH3NH
CH3
CH3NH2 CH3NCH3
CH3
(CH3)3N(CH3)2NH
Methylamine(a 1° amine)
Dimethylamine(a 2° amine)
Trimethylamine(a 3° amine)
or or
Aldehydes and Ketones• Both contain a C=O (carbonyl) groupC=O (carbonyl) group
– aldehyde:aldehyde: contains a carbonyl group bonded to a hydrogen; in formaldehyde, the simplest aldehyde, the carbonyl group is bonded to two hydrogens
– ketone:ketone: contains a carbonyl group bonded to two carbon atoms
CH3CHO O
CH3CCH3C-C-HR
R
ROC-C-C
O
RR
RR
R R
Functionalgroup
Functionalgroup
Acetaldehyde(an aldehyde)
Acetone(a ketone)
Carboxylic Acids
• Carboxylic acid:Carboxylic acid: a compound a compound containingcontaining a -COOH (carboxyl: carbcarbonyl + hydroxyloxyl) group – in a condensed structural formula, a
carboxyl group may also be written -CO2H.
RCOHO
CH3COHO
Functionalgroup
Acetic acid(a carboxylic acid)
• Biochemical molecules –are just BIG organic molecules
–react like organic molecules
• Need to understand organic chemistry in order to understand and appreciate biochemistry