Halogenoalkanes and aromatics Flashcards

1
Q

Nomenclature of halogen alkanes

A
  • The halogen and o e.g. floro, bromo
  • Location and number must be specified e.g. di, tri, tetra
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2
Q

What intermolecular forces do halogenalkanes have

A
  • Due to the high electronegativity of the halogen atom it will attract electrons making it slightly negative and the carbon will be slightly positive.
  • They have a permanent dipole so have permanent dipole-permanent dipole interactions
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3
Q

What is a chloroflourocarbon

A
  • Halogenalkene with all the hydrogens relaced by flourene or chlorine
  • CFC’s are damaging to the ozone layer
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4
Q

Whats homolytic fission

A

The breaking of a covalent bond such that both atoms have an unpaired electron

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5
Q

Initiation of chlorine

A

Uv light breaks the bond between a Cl2 molecule to produce 2 chlorine free radicals

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6
Q

Propogation of Cl

A

The reaction of any particals that produces a free radical so the reactions can keep occuring

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7
Q

Termination of Cl

A

Any reaction that doesnt form a free radical such as 2 free radicals coming together or 2 carbons bonding

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8
Q

Whats a nucleophile

A

A chemical species that donates an electron pair to an electron deficient centre

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9
Q

Nucleophilic substitution (SN2)

A
  1. The nucleophile attacks the electron deficient carbon atom
  2. An intermediate with both atoms bonded is formed
  3. The bond between the carbon and halogen breaks giving the halogen the electrons
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10
Q

Nucleophilic substitution (SN1)

A
  1. The bond to the halogen breaks
  2. A carbonium ion intermediate is formed
  3. The nucleophile attacks the carbon
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11
Q

How to test for halide ions

A
  1. The halogenalkane must be hydrolysed by boiling it in sodium hydroxide
  2. It is acified with dilute nitric acid
  3. Aqueous silver nitrate is added
  4. A precipitate is formed
  5. If chloride is its white, bromide is cream and iodide is yellow
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12
Q

Elimination of halogenalkanes

A
  • High temp without air
  • In the presence of a strong base
  • The halogen accepts the electrons breaking the bond between it and the carbon
  • The electrons between carbon and hydrogen then form a C=C and the base accepts the proton given off
  • Whats produced is an alkene, Base-H and lone halogen atom
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13
Q

Whats a leaving group

A
  • An atom that can accept electrons and leave a molecule
  • Often a halogen
  • A good leaving group has a high electronegativity
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14
Q

What is an aromatic compound

A

Any compound that contains atleast one benzene ring

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15
Q

Describe the bonding in a benzene ring

A
  • Sigma bonds between carbons
  • Pi bonds above and below due to P-orbitals
  • Rings of 6 delocalised electrons above and below the ring
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16
Q

Nomenclature of aromatic compounds

A
  1. Carbon number 1 is wherever the other molecule is attached
  2. OH = phenol, always on carbon 1
  3. Alphabetical order
16
Q

Nomenclature of aromatic compounds

A
  1. Carbon number 1 is wherever the other molecule is attached
  2. OH = phenol, always on carbon 1
  3. Alphabetical order
17
Q

Mechanism of chlorination of benzene

A
  1. AlCl3 accepts a pair of electrons from Cl2 to generate a Cl+ electrophile
  2. Electrons from the benzene ring go to the cl+ forming a bond, the ring will have a u+ inside
  3. The H-C bond is broken giving the electrons to the ring
  4. A H+ is produced
18
Q

Mechanism of Friedel-Crafts alkylation

A
  1. An electrophile (CH3+) is generated by reacting CH3Cl with AlCl3
  2. Electrons from the inner ring are transfered to the akyl group forming a bond
  3. The ring becomes a u+
  4. The C-H next to the akyl group is broken and the electrons are transfered to the ring
  5. The H+ is released as a product
19
Q

Acylation of benzene

A

The same as chlorinaton and akylation but with COCH3

20
Q

Substituent effects on benzene

A
  • Alkyls are activating
  • Halogens are deactivating
  • NO2 is deactivating
  • OH is activating
  • Activation occurs when electron density is increased
21
Q

General mechanism for electrophilic substitution to phenol and phenylamine

A

The reactants bond to the 2, 4 and 6 carbons and 3 hydrogens are produced

22
Q

Reaction of phenol with sodium

A
  • Na replaces the H in the alcohol to form a O-Na+
  • hydrogen gas is a product
23
Q

Why can phenol act as a nucleophile

A
  • Theres a lone pair on the O