chapter 2: carbon compounds hydrocarbons consist of only carbon and hydrogen atoms alkanes—contain...
TRANSCRIPT
Chapter 2: Carbon Compounds
Hydrocarbons• Consist of only Carbon and Hydrogen Atoms
• Alkanes—Contain the Maximum # of H Atoms
• Alkenes—Hydrocarbons w/ Double Bond(s)
Ethene Propene Butadiene
CH4 H3C CH3
Methane Ethane Propane
Hydrocarbons Continued
• Alkynes—Hydrocarbons w/ Triple Bond(s)
Ethyne Propyne 1-Butyne 2-Butyne
• Alkanes: Referred to as Saturated Compounds(Contain Maximum # of Hydrogen Atoms)
• Alkenes/Alkynes: Unsaturated Compounds;Can React w/ H2 (Hydrogenation Reactions)
Aromatic Compounds: Benzene
• Benzene/Aromatics are Special Class
• Understood in Terms of Kekulé Structures or MOs
Polar Covalent Bonds
H—Cl
H—Br
C═O
• Electronegativity Difference Pulls ElectronDensity Toward More Electronegative Atom
• This Creates What is Called a Dipole
• Unit of Dipole Moment Measure: Debye
H Br
For Bonds, Dipole Moment is Indicated w/ Arrow From Leastto Most Electronegative; What About Molecular Dipoles?
Polar and Nonpolar Molecules
Polar Nonpolar
NH3 CO2
H2O BH3
CH3Cl CH4
CH2Cl2 CCl4
CH3CH2OH Benzene
H3C-O-CH3 Diatomics (Cl2, Br2, etc.)
• Look at Individual Dipole Moments; Check for Net
Polar and Nonpolar Molecules (2)
Cl
Cl
Br
Br
Cl Cl
Br Br
NON POLAR POLAR
trans-dichloroethene
trans-dibromoethene
cis-dichloroethene
cis-dibromoethene
Functional Groups
1. Alkyl Groups(R)
Alkanes can be Generally Represented as R-H
Parent HC Alkyl Group Abbreviation
Methane methyl Me
Ethane ethyl Et
Propane propyl Pr
isopropyl iPr
Functional Groups
2. Alkyl Halides
ClCl
Cl
1o Halide 2o Halide 3o Halide
• Look at Carbon w/ Halide attached
• 1 C Attached—Primary; 2 C Attached—Secondary
3 C Attached--Tertiary
Functional Groups
3. Alcohols
• Look at Carbon w/ Alcohol attached
• 1 C Attached—Primary; 2 C Attached—Secondary
3 C Attached—Tertiary
• Replace O with S; now have a Thiol
OHOH
OH
1o Alcohol 2o Alcohol 3o Alcohol
Functional Groups
4. Ethers
OO
O
OO
dimethyl ether diethyl ether ethyl propyl ether
ethylene oxide tetrahydrofuran
• Name “sides” of ether in alphabetical order
Functional Groups
5. Amines
• Note: amines are utile as bases in organic reactions
1o Amine 2o Amine 3o Amine
NH2H3CHN N
NH2
NH
NH
ethyl amine diethyl amine piperidine
Functional Groups
6. Hydrazines
• Note: hydrazines react with aldehydes/ketones
H2N NH2 N NNH
NH
N
N NOT:
NH
HN
Functional Groups
7. Carbonyls: Aldehydes and Ketones
• Note: C=O common link between aldehydes/ketones
R H
O
R R
O
R R'
O
Aldehyde Ketones
H H
O
O
O O
O
Formaldehyde Acetone Cyclohexanone
Propanal Ethyl methyl ketone
Functional Groups
8. Carboxylic Acids
• Question: What helps makes this functionality acidic?
H
O
OH
O
OH
O
OH
O
OH
Formic Acid Acetic Acid
Benzoic Acid Propanoic Acid
Functional Groups
9. Esters
• Note: CYCLIC esters are a special case called LACTONES
O
O
O
O
O
O
O
O
ethyl acetate propyl acetate
ethyl propionate methyl benzoate
Functional Groups
10. Amides
• Note: CYCLIC amides are a special case called LACTAMS
• Amides have restricted rotation about the C-N bond. Why?
NH2
O
NH
O
N
O
acetamide N-methyl acetamide N,N dimethylacetamide
Functional Groups
11. Nitriles (Cyano)
• See Table 2.3 for a Good Summary of Functional Groups
CN CNCN
acetonitrile(ethanenitrile)
butanenitrile propenenitrile(acrylonitrile)
Multiple Functional Groups; 1 Molecule
O N
O
O
O
O
N OH
Cl
OMe
Cryptophycin 3
Intermolecular Forces
1. Van der Waals Interactions
2. Dipole-Dipole InteractionsConsider how molecules with permanent dipoles align
3. Hydrogen BondingVery strong electron delocalizations
4. IonicVery strong electrostatic interactions
Hydrogen Bonding
OH
H
O
O
H
O H
• H-Bonds nearly linear (O-H-O)
• Electrons from an O lone pair *(OH)