Chapter 13 Alkenes Flashcards
unsaturated
Containing a multiple carbon-carbon bond.
π-bond
A bond formed by the sideways overlap of two p-orbitals, with the electron density above and the plane of the bonding atoms.
stereoisomers
Compounds with the same structural formula but with a different arrangement of the atoms in space.
E/Z isomerism
A type of stereoisomerism in which different groups attached to each carbon of a C=C double bond may be arranged differently in space because of the restricted rotation of the C=C bond.
Each carbon in the double bond must be attached to two different groups
optical isomers
Stereoisomers that are nonsuperimposable mirror images of each other; also called ‘enantiomers’.
cis–trans isomerism
A special type of E/Z isomerism in which there are two non-hydrogen groups and two hydrogen atoms around the C=C double bond: the cis isomer (Z isomer) has H atoms on each carbon on the same side; the trans isomer (E isomer) has H atoms on each carbon on different sides.
Hydrogenation of alkenes
Alkene is mixed with hydrogen and passed over a nickel catalyst at 423K to form and alkene.
Addition reaction
Halogenation of alkenes
Alkene addition reaction with Cl or Br at room temp to form a dihaloalkane
Addition reactions of alkenes with hydrogen halides
react with gaseous hydrogen halides at room temp to form haloalkanes
Hydration of alkenes
alcohols are formed when alkenes react with steam in the presence of a phosphoric acid catalyst H3PO4
electrophilic addition
An addition reaction in which the first step is attack by an electrophile on a region of high electron density.
electrophile
An atom (or group of atoms) which is attracted to an electron-rich centre or atom, where it accepts a pair of electrons to form a new covalent bond.
carbocation
An ion that contains a positively charged carbon atom.
primary
On a carbon atom at the end of a chain.
secondary
On a carbon atom to which two carbon chains are attached.
