18A.2 Flashcards

1
Q

What are the reactions that benzene undergoes as a hydrocarbon

A
  1. Hydrogenation
  2. Combustion
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2
Q

how does hydrogenation reaction of Benzene occur, under what conditions, and with what catalyst used

A

by mixing benzene with hydrogen and heating under pressure with a Ni catalyst

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3
Q

what is the skeletal and molecular formula of the hydrogenation of Benzene

A

page 226 (product is cyclohexane)

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4
Q

what is observed with the combustion of benzene

A

a smoky flame forms, which is typical for compounds with high carbon-to-hydrogen ratio

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5
Q

what is the formula for the combustion of Benzene

A

benzene burns in air to form

C6H6 + 7.5O2 —> 3H2O +6CO2

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6
Q

what are the reactions of Benzene as a arene

A
  1. Bromination
  2. Nitration
  3. Friedel-Crafts reactions: alkylation, and acylation
  4. Sulfonation
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7
Q

the most important reaction of benzene are

A

substitution

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8
Q

in substitution of benzene the products are

A

aromatic

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9
Q

Bromination refers to

A

Putting bromine into a molecule

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10
Q

what are the condition for Bromination of Benzene

A

Bromine and Benzene are heated under reflux, with the presence of a catalyst called hydrogen-carrier

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11
Q

what is a hydrogen carrier

A

a compound such as AlX3, or FeX3 (metal-hydrogen), where X is a halogen, that can catalyse the halogenation of arenes. they produce a stronger electrophile, such as Br^+

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12
Q

what is the halogen carrier used to catalyse the Bromination of benzene

A

iron fillings as they can react with some of the bromine to form Iron(iii) bromide

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13
Q

what is the reaction for the Bromination of Benzene

A

page 226

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14
Q

what this nitration mean

A

the replacement of a hydrogen group by a nitro group (NO2) (note don’t mistake with nitrogen dioxide gas)

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15
Q

how does reaction Nitration of Benzene occur, under what conditions, and with what catalyst used

A

By warming benzene (to about 50 - 60c) with a mixture of concentrated nitric acid and sulfuric acid. nitric acid can be considered the source of the nitro group and sulfuric acid is catalyst of the reaction

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16
Q

what is the Nitration of benzene (reaction)

A

page 226 products are water and nitrobenzene

17
Q

why is the nitration of benzene taking place between temp of 50 to 60

A

because any lower would be too slow and any higher would form dinitrobenzene or even trinitrobenzene

18
Q

what are the 3 things to consider with alkylation and acylation

A
  1. using a regent of XY one of the hydrogen atoms in Benzene is substituted by Y and the other product is HX
  2. A catalyst is needed (halogen carrier) often Aluminium Chloride, but other halogen carriers such as Iron(iii) chloride and Iron(iii) bromide also work
  3. anhydrous condition are needed because water would react with the catalyst and sometimes also with organic compound
19
Q

what are the two Friedel-Crafts reactions we need to know

A

alkylation, and acylation

20
Q

when using a halogen carrier catalysts conditions need to be … and and why

A

anhydrous because water can react with the catalyst

21
Q

what is alkylation

A

the substitution of one hydrogen atoms of Benzene with a alkyl group

22
Q

what is alkylation of benzene reaction (regent, products)

A

regent is a halogenoalkane, and the products are hydrogen X and Alkylbenzene page 227

23
Q

what is acylation

A

the substitution of one hydrogen atoms of Benzene with an acyl group

24
Q

what is acylation of benzene reaction (regent/product)

A

regent acyl chloride and the products are ketone, and HCl

25
Q

what sulfonation

A

the replacement of one hydrogen atom by a SO3H group

26
Q

how does reaction sulfonation of Benzene occur, under what conditions, and with what catalyst used

A

benzene is warmed with fuming sulfuric acid at 40c for 20 to 30 minutes, i think catalyst is fuming sulfuric acid

27
Q

what is the sulfonation of Benzene reaction

A

product water and benzenesulfonic acid page 227

28
Q

how is fuming sulfuric acid made

A

by dissolving sulfur(VI) oxide (sulfur trioxide SO3) in concentrated sulfuric acid

29
Q

the addition reaction between benzene and bromine can occur in the presence of

A

UV radiation

30
Q

what is there to note about sulfonation

A

sometimes you can use SO3 electrophile as a regent but it depends of the question say it is reaction with the SO3 or H2SO4,

31
Q

what is the equation for the sulfonation of benzene using SO3

A

page 227 same products without HCl

32
Q

what is the only new rule there is when naming a aromatic product

A

benzene ring is resented as Phenyl (or phen) of attached to another functional group