18A.2 Flashcards
What are the reactions that benzene undergoes as a hydrocarbon
- Hydrogenation
- Combustion
how does hydrogenation reaction of Benzene occur, under what conditions, and with what catalyst used
by mixing benzene with hydrogen and heating under pressure with a Ni catalyst
what is the skeletal and molecular formula of the hydrogenation of Benzene
page 226 (product is cyclohexane)
what is observed with the combustion of benzene
a smoky flame forms, which is typical for compounds with high carbon-to-hydrogen ratio
what is the formula for the combustion of Benzene
benzene burns in air to form
C6H6 + 7.5O2 —> 3H2O +6CO2
what are the reactions of Benzene as a arene
- Bromination
- Nitration
- Friedel-Crafts reactions: alkylation, and acylation
- Sulfonation
the most important reaction of benzene are
substitution
in substitution of benzene the products are
aromatic
Bromination refers to
Putting bromine into a molecule
what are the condition for Bromination of Benzene
Bromine and Benzene are heated under reflux, with the presence of a catalyst called hydrogen-carrier
what is a hydrogen carrier
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^+
what is the halogen carrier used to catalyse the Bromination of benzene
iron fillings as they can react with some of the bromine to form Iron(iii) bromide
what is the reaction for the Bromination of Benzene
page 226
what this nitration mean
the replacement of a hydrogen group by a nitro group (NO2) (note don’t mistake with nitrogen dioxide gas)
how does reaction Nitration of Benzene occur, under what conditions, and with what catalyst used
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
what is the Nitration of benzene (reaction)
page 226 products are water and nitrobenzene
why is the nitration of benzene taking place between temp of 50 to 60
because any lower would be too slow and any higher would form dinitrobenzene or even trinitrobenzene
what are the 3 things to consider with alkylation and acylation
- using a regent of XY one of the hydrogen atoms in Benzene is substituted by Y and the other product is HX
- A catalyst is needed (halogen carrier) often Aluminium Chloride, but other halogen carriers such as Iron(iii) chloride and Iron(iii) bromide also work
- anhydrous condition are needed because water would react with the catalyst and sometimes also with organic compound
what are the two Friedel-Crafts reactions we need to know
alkylation, and acylation
when using a halogen carrier catalysts conditions need to be … and and why
anhydrous because water can react with the catalyst
what is alkylation
the substitution of one hydrogen atoms of Benzene with a alkyl group
what is alkylation of benzene reaction (regent, products)
regent is a halogenoalkane, and the products are hydrogen X and Alkylbenzene page 227
what is acylation
the substitution of one hydrogen atoms of Benzene with an acyl group
what is acylation of benzene reaction (regent/product)
regent acyl chloride and the products are ketone, and HCl
