Revision Flashcards
What is Bond fission?
When an organic reaction takes place, bonds in the reactant molecules are broken and
bonds in the product molecules are made. The process of bond breaking is known as bond
fission.
What is Homolytic bond fission?
- results in the formation of two neutral radicals
- occurs when each atom retains one electron from the sigma covalent bond and the bond breaks evenly
- normally occurs when non-polar covalent bonds are broken
- Requires UV to do so
What is heterolytic bond fission?
- results in the formation of two oppositely charged ions
- occurs when one atom retains both electrons from the sigma covalent bond and the bond
breaks unevenly - normally occurs when polar covalent bonds are broken
How is Homolytic bond fission indicated?
two single-headed arrows starting at the middle of a covalent bond indicate homolytic bond fission is occurring
How is heterolytic bond fission indicated?
two double-headed arrow starting at the middle of a covalent bond indicates heterolytic bond fission is occurring
What do double headed arrows indicate?
a double-headed arrow indicates the movement of an electron pair
What do single headed arrow indicate?
a single-headed arrow indicates the movement of a single electron
What are nucleophiles?
- negatively charged ions or neutral molecules that are electron rich
- attracted towards atoms bearing a partial positive or full positive charge
- capable of donating an electron pair to form a new covalent bond
What are some examples of nucleophiles?
Chloride ion, bromide ion, hydroxide ion, cyanide ion, ammonium and water
What are electrophiles?
- positively charged ions or neutral molecules that are electron deficient
- attracted towards atoms bearing a partial or full negative charge
- capable of accepting an electron pair to form a new covalent bond
What is skeletal formula?
In a skeletal structural formula, neither the carbon atoms, nor any hydrogens attached to the carbon atoms, are shown
What are haloalkanes?
Haloalkanes (alkyl halides) are substituted alkanes in which one or more of the hydrogen
atoms is replaced with a halogen atom
What are monohaloalkanes?
- contain only one halogen atom
- can be classified as primary, secondary or tertiary according to the number of alkyl groups attached to the carbon atom containing the halogen atom
What is SN1?
- nucleophilic substitution reaction
- one species in the rate determining step
- occurs in a minimum of two steps
- via a trigonal planar carbocation intermediate.
What is SN2?
- nucleophilic substitution reaction
- two species in the rate determining step
- occurs in a single step
- via a single five-centred, trigonal bipyramidal transition state