F322-Alkenes Flashcards
Unsaturated
Containing at least one Carbon to Carbon multiple bond
Hydrocarbon
Compounds containing Carbon and Hydrogen atoms only
General formula for Alkene
CnH2n
Homologous Series
A series of organic compounds having the same functional group but with each successive member differing by CH2
Chemical bonding between Carbon & Hydrogen atoms
Covalent bonds
First 9 Alkenes
Ethene Propene Butane Pentene Hexene Heptane Octene Nonene Decene
Structural Isomer
Compounds with the same molecular formula but different structural formula
Stereoisomers
Compounds with the same structural formula but with a different arrangements of the atoms in space
E/Z Isomerism
An example of stereoisomerism. In terms restricted rotation about a double bond and the requirement for two different groups to be attached to each carbon of the C=C group.
Cis-Trans Isomers
A special case of E/Z isomerism in which two of the substituent groups are the same
Name the shape around the carbon atom in an Alkene
Trigonal Planar
Functional Group
A group of atoms responsible for the characteristic reactions of a compound
Electrophile
A species attracted to an electron rich centre where it accepts a pair of electrons to form a new covalent bond
Hydrogenation catalyst.. Including function.
Nickel Catalyst - lowers activation energy by making bonds weaker
Equation for Hydrogenation
Alkene + H2 > Alkane
Temperature/use of Hydrogenation
150*C & is important in the manufacture of margarine (hardening of veg oils)
What happens to Alkenes during Hydrogenation
Alkenes are reduced by Hydrogen Gas
What happens to Alkenes during Halogenation
Alkenes react rapidly with Bromine/Chlorine
What is halogenation a test for?
A test for unsaturation- alkenes decolourise bromine water
Equation for Halogenation
Ethene + Br2/Cl2 > 1,2 -dibromoethane/ 1,2 -dichloroethane
What does the reaction with halides form?
Halogenoalkanes
What is the equation for a reaction with hydrogen halides?
Ethene + HCl/HBr > chloro/bromoethane
What are alkenes reacted with in Hydration?
Steam
What catalyst is used in Hydration?
Phosphoric Acid Catalyst (H3PO4)
What does Hydration result in?
Alcohols
What is Hydration a major industrial process for?
The manufacture of ethanol in UK
Overall equation of Electrophillic Addition
CH2=CH2 + Br2 > CH2BrCH2Br
What is the first step of Electrophillic addition?
Heterolytic Fission- the breaking of a covalent bond where the shared pair of electrons are not split equally forming a cation (p) and an anion (n)
Curly Arrow
The movement of an electron pair, showing either the breaking or formation of a covalent bond
What occurs in step 2 of Electrophillic Addition?
A highly reactive Carbocation is formed which then rapidly forms a covalent bond with the bromide ion
Electrophillic Addition-
Electrons in the double bond repel electrons in the bromine molecule…
Inducing a dipole
Give the formula of Ethyne
C2H2 …. H-C(triple bond)C-H
General formula for alkynes
CnH(2n-2)
Describe the overlap of p-orbitals to form a pi bond
The pi-bond is formed by sideways overlap of p-orbitals above and below the plane of the molecule
What matches a Z-isomer
Cis-isomer
What matches an E-isomer?
Trans-isomer
