Flashcards in Alkenes Deck (38)
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1
What is a C=C double bond?
An area of high electron density
2
Why are alkenes highly reactive?
Their C=C double bond
3
How is the C=C double bond formed?
The overlap of a spare unbonded singly filled p-orbital present on each carbon atom in the bond
4
Can a C=C double bond be rotated?
NOPE
5
What is the general formula for alkenes?
Cn H2n
6
What is the bond angle and shape name for the C=C double bond in alkenes?
120
Planar
7
When naming alkenes what must you always check for?
E/Z isomerism
8
What is the only mechanism in the alkenes topic?
Electrophilic addition
9
Are alkenes or alkanes more reactive?
Alkenes
10
What is an electrophile?
A species that Accepts a pair of electrons
11
What area of alkenes is easily attacked by electrophiles?
Why?
The C=C double bond
It has a high electron density
12
Describe the mechanism to turn alkenes to alkanes briefly
Give this mechanism’s name
An electron pair is donated to the electrophile which causes C=C double bond to break, allowing each C to form bonds with other species
Electrophilic addition
13
Describe the electrophilic addition mechanism with the electrophile X-Y
1) an e- pair from the C=C bond forms a covalent bond with the delta positive X, breaking the X-Y bond and forming a :Y- ion. An intermediate with a *ve carbocation is formed
2) lone pair on :Y- forms a covalent bond with +ve carbon
14
In electrophilic addition with Bromine water, what does the :Br- ion act as?
A nucleophile
15
Bromine water is non-polar. How does electrophilic addition occur?
Electron rich double bond induces a dipole and delta positive Br acts as the electrophile
16
In a H-X molecule, where X is a halogen atom, which is delta positive?
The H is delta positive
17
How to write sulphuric acid for electrophilic addition
H-OSO3H
18
What is hydrolysis?
Splitting a molecule with water or another small molecule
19
What does the addition of ethyl hydrogen sulphate to water cause and produce?
What is the overall equation?
What does H2SO4 act as? Why?
Hydrolysis
Ethanol
CH2=CH2 +H2O —-> CH3CH2OH
A catalyst. It is not used up?
20
What is the most stable carbocation?
The least stable?
Tertiary
Primary
21
What is the major product formed from?
The more stable carbocation
22
How do you determine the class of the carbocation?
The number of carbon atoms directly bonded to the positively charged carbon atom
23
What is the stability of carbocations related to?
Why?
The presence of alkyl groups (CH3, CH2, CH)
Electron releasing relative to the hydrogen atoms and help to stabilise the positive charge on the carbocation
24
What is the electron releasing property of alkyl groups called?
Positive inductive effect
25
Will asymmetrical alkenes form equal amounts of each product?
No. The more stable carbocation intermediary will form more products than the less stable one
26
What is the mechanism to form a polymer ?
Addition polymerisation
27
What is the repeating unit for poly (ethene)?
H. H
|. |
-(-C-C-)-
|. |
H. H
28
Give the IUPAC name for PVC?
poly(chloroethene)
29
Describe normal PVC
Hard and rigid as there are permanent dipole-dipole forces between chains due to delta positive C and delta negative Cl
30
