AS Organic Chemistry Introduction Flashcards
What is a hydrocarbon?
A compound consisting solely of carbon and hydrogen
What is the functional group of an organic compound?
- A group of atoms that determines the compound’s chemical and physical properties
- Compounds can have multiple functional groups, though they have different priorities
What are the rules for drawing skeletal formulae?
- Single lines represent single bonds
- Double and triple lines represent double and triple bonds respectively
- The lines changing direction signifies a carbon atom
- All heteroatoms are shown like they are in displayed formulae
- Hydrogens are assumed to be present where a carbon atom has not already formed four bonds
What does R denote?
An alkyl group (alkane missing a hydrogen that is usually bonded to another carbon)
What do the functional groups for the homologous series alkene, halogenalkane, alcohol, aldehyde, ketone, carboxylic acid, ester, amine and nitrile look like?
What are the rules for the systematic nomenclature of aliphatic (straight-chain) compounds?
- The longest continuous carbon chain and the highest priority functional group dictate the suffix
- The carbon chain is numbered starting with the end closest to the highest priority functional group or alkyl groups if it’s an alkane
- Add the groups attached to the longest carbon chain as prefixes and indicate the number of the carbon on the longest carbon chain the group is attached to
- The prefixes should be in alphabetical order, regardless of position
- If multiple of the same group are present on the longest carbon chain, a prefix like di, tri or tetra is used, and the numbers of the carbons the groups are attached to are put before this new construction, separated by commas
- Dashes are used to separate numbers and groups and multiple prefixes, but not prefixes and suffixes
- Example: 3,4-dichloro-2,2-dimethylhexane
What are the suffixes of the functional groups for the homologous series alkene, halogenalkane, alcohol, aldehyde, ketone, carboxylic acid, ester, amine and nitrile?
What is the definition of homologous series?
A group of organic compounds that have the same functional group, the same general formula and the same chemical properties
What do curly arrows indicate in reaction mechanisms?
- The movement of electron pairs
- A curly arrow with a single head denotes the movement of a single electron, though this is less common
What is the difference between saturated and unsaturated compounds?
- Saturated compounds contain only single bonds, so each carbon is bonded to the maximum number of hydrogen atoms possible
- Unsaturated compounds have double or triple bonds involving carbon; this meansthese carbon atoms could bond to additional hydrogen atoms were the double or triple bonds not present
What is the difference between homolytic and heterolytic fission?
- Homolytic fission is when a covalent bond breaks and both atoms involved receive an electron from it, forming two radicals
- Heterolytic fission is when a covalent bond breaks and one atom (usually the more electronegative one) takes both atoms, forming a cation and an anion
What is the definition of a nucleophile?
- An electron rich species that is able to donate a pair of electrons
- Nucleophilic refers to a species that is a nucleophile or a reaction involving a nucleophile
What is the definition of an electrophile?
- An electron-deficient species that can accept a pair of electrons
- Electrophilic refers to a species that is an electrophile or a reaction involving an electrophile
What compounds are produced or used in condensation and hydrolysis reactions?
Almost always water, but sometimes other small molecules like HCl
What does [O] denote?
- One atom of oxygen from an oxidising agent
- In organic chemistry, oxidation usually involves the addition of (an) oxygen atom(s)
What does [H] denote?
- One atom of hydrogen from a reducing agent
- In organic chemistry, reduction often involves the addition of (a) hydrogen atom(s)
- This is because H is less electronegative than carbon, so reduces its oxidation number
How are the pi bonds arranged around a carbon atom with sp hybridisation bonded to another carbon with sp hybridisation?
- The carbon features a triple bond with another carbon
- Therefore, there are two pi bonds, the sideways overlap of p orbitals
- In one pi bond, the lobes of the two p orbitals lie above and below the plane of the sigma bond
- In the other pi bond, the lobes of the two p orbitals will lie in front of and behind the plane of the sigma bond to maximise overlap
What is a planar molecule?
A molecule that has all its atoms in the same plane, e.g. ethene
What are the two primary types of isomerism?
- Structural isomerism
- Stereoisomerism
What are the three types of structural isomerism?
- Explain what would differ between isomers of each type of structural isomerism
- Structural isomers have the same number and type of atoms but different connections between them (same molecule formulae but different structural and displayed formulae)
- Chain isomerism - same molecular formula but different longest carbon chain; caused by branching
- Positional isomerism - same molecular formula but different position of functional group
- Functional group isomerism - same molecular formula but different functional groups altogether
What are the two types of stereoisomerism?
No details required
Stereoisomers are compounds that have the same molecular and structural formula and the same connectivity of atoms, but differ in the spatial arrangement of these atoms
- Geometric isomerism
- Optical isomerism
All types of stereoisomers, geometric and optical, usually have different chemical and physical properties to one another
How does geometric isomerism arise due to the presence of a double bond?
- A double (or triple) bond has restricted rotation, so it matters which side of the double bond groups or atoms are bonded to
- This is because rotating the double bond would break it, requiring a large amount of energy
- Geometric isomerism arises when each carbon atom involved in a double bond has two different groups or atoms bonded to it
Ring compounds can also exhibit geometric isomerism as they cannot freely rotate
How are names assigned to geometric isomers?
- Cis or Z isomers have the two highest priority groups (one on each carbon) on the same side of the double bond
- Trans or E isomers have the two highest priority groups (one on each carbon) on opposite sides of the double bond
- Priority is determined by the magnitude of atomic number (moving down the chain to break ties; for example, CH₂OH is higher than CH₃ as its chain goes CHHO instead of CHHH)
- For example, cis-1,2-ethenediol would have the two hydroxyl groups on the same side of the double bond
What is a chiral centre?
A carbon atom with four different groups or atoms bonded to it
