Synthesis Flashcards
What is bond fission?
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
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
What are nucleophiles?
negatively charged ions or neutral molecules that are electron
rich, such as
Cl^- , Br^- , OH^- , CN^-
, NH3 and H2O
What are nucleophiles attracted to?
attracted towards atoms bearing a partial or full positive charge
What are electrophiles?
positively charged ions or neutral molecules that are electron
deficient, such as
H^+, NO2^+ and SO3
What are electrophiles attracted to?
attracted towards atoms bearing a partial or full negative charge
What is an SN1 reaction?
SN1 is a nucleophilic substitution reaction with one species in the rate
determining step and occurs in a minimum of two steps via a trigonal
planar carbocation intermediate
What is an SN2 reaction?
SN2 is a nucleophilic substitution reaction with two species in the rate
determining step and occurs in a single step via a single five-centred,
trigonal bipyramidal transition state
What molecules favours SN1 reactions?
Tertiary molecules
What molecules favours SN2 reactions?
Primary molecules.
Why do ethers have lower boiling points than alcohols?
Due to the lack of hydrogen bonding between ether molecules, they
have lower boiling points than the corresponding isomeric alcohols
Why are larger ethers insoluble in water?
Larger ethers are insoluble in water due to their increased molecular size.
Why are ethers often used as solvents?
Ethers are commonly used as solvents since they are relatively inert chemically and will dissolve many organic compounds.
What does Markovnikov’s rule state?
Markovnikov’s rule states that when a hydrogen halide or water is added to an unsymmetrical alkene, the hydrogen atom becomes
attached to the carbon with the most hydrogen atoms attached to it
already.
Why do primary and secondary amines have higher boiling points?
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hydrogen bonding. As a result, primary and secondary amines have
higher boiling points than isomeric tertiary amines.
Why are amines soluble in water?
hydrogen-bond
with water molecules, thus explaining the appreciable solubility of the
shorter chain length amines in water.
What has sp3 hybridisation
C-C single bonds
What has sp2 hydridisation?
C-C double bonds
What has sp hybridisation?
C-C triple bonds
What do monohaloalkanes react with to form Alcohols?
Aqueous alkali such as KOH or NaOH
What type of reaction is monohaloalkanes to alcohols?
nucleophilic substitution
What is inductive effect?
The alkyl R group have a positive inductive effect. They are electron donating and push electrons towards the positive charge on the varbon which helps to stabilise it.
What is steric effect?
The size of the alkyl group on the haloalkane causes and important effect. In SN2 mechanism the nucleophile attacks from the opposite side of the halogen. Tertiary haloalkanes with resist the attack as it is sterically hindered and the three bulky alkyl groups prevent access to the positive carbon
