Unit 4 - Structure of Organic Compounds Flashcards
Bonding in Carbon Compounds
Carbon atoms contain 6 electrons - two in first shell and four in second shell
A carbon atom can form four covalent bonds with up to four other carbon atoms
Saturated vs Unsaturated Carbon Bonds
A molecule that contants only one single carbon-carbon bond is described as a saturated molecule
A molecule that contains a double or triple cabron-carbon bond is described as unsaturated molecule
Stability of Carbon Bonds
Bond energy is the measure of bond strength and is the amount of energy required to break the covalent bond
^Energy ^Bond Strength
Hydrocarbons
Some organic molecules are made up only carbon and hydrogen are defined as hyrdrocarbons.
Most organic molecules contain elements in addition to carbon and hydrogen including oxygen, nitrogen, sulfur or chlorine
Functional Groups
A functional group is defined as an atom or a group of atoms that gives a characteristic set of chemical properties to a molecule containing these atoms.
Class of Organic Compound - Alkane
Alakane
Functional group: none
Example: Ethane
Class of Organic Compound - Alkene
Alkene
Functional Group: Double bond carbon
Example: Ethene
Class of Organic Compound - Alkyne
Alkyne
Functional Group: Triple bond carbon
Example: Ethyne
Class of Organic Compoound - Haloalkane
Haloalkane
Functional Group: halogen (group 7 elements)
R-X (where R is the carbon bond and X = F, Cl, Br, I)
Example: Chloroethane
Class of Organic Compound - Alcohol
Alcohol
Functional group: Hyrdoxyl, R - OH
Example: Ethanol
Class of Organic Compound - Amine
Amine
Functional Group: Amino, R - NH2
Example: Ethanomine
Class of Organic Coumpound - Aldehyde
Aldehyde
Functional group: Carbonyl (attached to the a hydrogen atom)
O
II
R - C - H
Example: Ethanal
Class of Organic Compound - Ketone
Ketone
Functional Group: Carbonyl (attatched to a carbon atoms on either side)
O
II
R - C - R
Example: Propanone
Class of Organic Compound - Carboxylic Acid
Carboxylic Acid
Functional Group: Carboxyl
O
II
R - C - OH
Example: Ethanoic acid
Class of Organic Compound - Ester
Ester
Functional Group: Carboxylate
O
II
R - C - O - R
Example: Methyl ethanoate
Class of Organic Compound - Amide
Amide
Functional group: Carboxamide
O
II
R - C - NH2
Example: Ethanamide
Class of Organic Compound - Nitrile
Nitrile
Functional Group: Nitrile
R - C - (triple bond) - N
Example: Ethanentrile
General Groupings
Alkane + Alkene + Alkyne
Haloalkane + Alcohol + Amine
Aldehyde + Ketone + Carboxylic Acid + Ester + Amide
Naming with number placement
1 - Meth 6 - He
2 - Eth 7 - Hep
3 - Prop 8 - Oct
4 - But 9 - Nona
5 - Pent 10 - Dec
Homologous Series
A homologous series is a class of molecules in which each member differs by - CH2- from the previous member.
Alkanes, Alkenes, Alkynes all have homologous series
Compounds from the same homologous series contains:
- a similar structure
- a pattern to the physical properties
- similar chemical properties
- the same general formula
Chain Isomers
Chain isomers are a consequence of the branching that is possible in carbon chains. The more atoms in the molecule, the more structural isomers are possible
(E.g CH6. C2H6, C3H8, all have 0 chain isomers
C4H10 has 2 chain isomers)
Positional Isomers
Positional isomers only exist for molecules that contain a functional group and have a long enough carbon chain so that the different positions for the functional group are possible.
For these isomers, the molecular formula (C6H12) stay the same, however the naming increases or decreases (i.e hexane, hex-2-ane, hex-3-ane)
Stereoisomers
Two types: optical and geomertic isomers
Geometric Isomers
Called cis-trans isomers and can occur when there is restricted rotation somwhere in a molecule. Restricted rotation can occur about a carbon-carbon double bond or a ring
Cis - Trans Isomers
Because the way electrons are arranged in a double bond, groups attached to either side of the double bond are unable to rotate freely
these isomers can only occur when each carbon atom in the double bond is attached to two different groups
Cis - Trans Isomer Structure
A C
/ /
C= C
/ /
B D
Cis - Trans Isomers cannot occur if A and B are the same
Cis Isomers occur when A and C are the same
Trans Isomers occur when A and D are the same
Alkyl Groups
H
I
H - C
I
H
Determing primary, secondary and tertiary structures
Primary - The carbon bonded to the halogen is only bonded to one alkyl group
Secondary - The carbon bonded to the halogen is also bonded to two alkyl groups
Tertiary - The carbon bonded to the halogen is also bonded to three alkyl groups
(Same as alcohol)
Naming Structures (Points)
Naming aldehydes - add ‘al’ at the end
Naming ketones - add ‘one’ at the end
Naming carboxylic acid - add ‘oic acid’ at the end
Naming amides - add ‘amide’ at the end
IUPAC Naming Rank
**Highest **
Carboxyl - ‘oic acid’
Ester - ‘oate’
Amide - ‘amide’
Carbonyl (aldheyde) - ‘al’
Carboyl (Ketone) - ‘one’
Hydroxyl - ‘ol’
Amino - ‘amine’
Alkene - ‘ene’
Alkyne - ‘yne’
Halo -
**Lowest **
