ALKENES AND CYCLOALKENES
Compounds with         C - C      0,154 nm     and   C – H    bonds
       C = C     0, 134 nm    and    =C-H    bonds
Bonding energy         C – C    351 kJ/mol s - bond
                                     C = C    610 kJ/mol       D = 259 kJ/mol p - bond

ALKENES AND CYCLOALKENES
Nomenclature
ethene, ethylene
ethenyl- , vinyl-
prop-2-en-1-yl, allyl-
prop-1-en-1-yl
prop-1-en-2-yl
Geometric isomerie
propene,
propylene
butene
but-2-ene
cis-but-2-ene                   trans-but-2-ene
application cis- and trans- is suitable only for simple molecules

ALKENES AND CYCLOALKENES
STABILITY of alkenes
cis-
trans-
stability of trans-isomer is higher
HEAT OF HYDROGENATION

ALKENES AND CYCLOALKENES
the more the systeme at the double bond is branched, the more is stable


ALKENES AND CYCLOALKENES
all cycloalkenes with less than 6 atoms in a ring are only known as cis- isomers
only stable is trans-cyclooctene

ALKENES AND CYCLOALKENES
THE MAIN DIRECTION OF ALKENE REACTIVITY
ADDITION   REACTION
Reactions are stereospecific
During addition of symmetrical molecule to non-symmetrically substituted olefine
enantiomers are created – reaction is stereospecific- trans- (anti-) addition

Stereospecific mechanism of additions



Regiospecific mechanism of additions



Regiospecific mechanism of additions



Regiospecific mechanism of additions