Aronatic Chmistry
27.| ARENES 27.2 PROPERTIES
Acenes are hudroLarbons based On
other benzene, Cot. An arene Lan hawe
tunctional groups replacng
structue
One or more hydrogen atom, in ts
Benzene
- althouah
unsatwated,ts very stable
hexagono cng structue,20° bond
-
planar shape angle
(-C bonds cauain length
-
between sinqle and double bond
Each carbon has 3 covalent
bonda
spare eletrons n p obitay overlap to torm
delocalised eletrons
Ly one tron eah carbon
Evdence
+ H, AH - 120Jmol
Expeted Hhydaogenabcr
+3H, ’
ot cyclohexa bnene : -360
DH -360kJmol Actual DH tor benzene is
less exothemc by lS2kma
+ 3H,
AH:203Jmol Benzene mort stable
Physical Properties!
Benzene Is a colourless iquid at room tempLrature
Hiajh meltng pont planar molecules packtogetlh e wel ina sald
Mixes ith hydroLaraons and non polar solveats, but not water
Combustion
Arenes burn with asmoky tlane, due to the hgh carbon to
hydroqen ratio. Unburnt carben produces soot
27.| ARENES 27.2 PROPERTIES
Acenes are hudroLarbons based On
other benzene, Cot. An arene Lan hawe
tunctional groups replacng
structue
One or more hydrogen atom, in ts
Benzene
- althouah
unsatwated,ts very stable
hexagono cng structue,20° bond
-
planar shape angle
(-C bonds cauain length
-
between sinqle and double bond
Each carbon has 3 covalent
bonda
spare eletrons n p obitay overlap to torm
delocalised eletrons
Ly one tron eah carbon
Evdence
+ H, AH - 120Jmol
Expeted Hhydaogenabcr
+3H, ’
ot cyclohexa bnene : -360
DH -360kJmol Actual DH tor benzene is
less exothemc by lS2kma
+ 3H,
AH:203Jmol Benzene mort stable
Physical Properties!
Benzene Is a colourless iquid at room tempLrature
Hiajh meltng pont planar molecules packtogetlh e wel ina sald
Mixes ith hydroLaraons and non polar solveats, but not water
Combustion
Arenes burn with asmoky tlane, due to the hgh carbon to
hydroqen ratio. Unburnt carben produces soot
