4B - Alkenes Flashcards Preview

AS Chemistry > 4B - Alkenes > Flashcards

Flashcards in 4B - Alkenes Deck (21):
1

Test for a C=C double bond?

Add bromine water to the solution.

Colour change = Orange brown → Colourless if C=C bond is present.

If no C=C bond is present then solution remains orange brown.

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2

Name the mechanism for which you use an alkene to form a haloalkane by: Alkene + Halogen

 

Give the conditions required for the reaction

Mechanism = Electrophilic addition reaction

Condition = RTP, No UV light

3

Draw the mechanism for the formation of 1,2-dibromoethane.

 

What is acting as the electrophile?

Electrophile in this reaction is the bromine.

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4

What type of bond fission is electrophilic addition?

Hetrolytic fission

5

Draw the mechanism for the synthesis of 2-bromopropane.

 

Why is 2-bromopropane the preferred product in terms of relative stabilities of the possible organic intermediates (carbocations)?

The hydrogen atom will add onto the carbon that has the most number of hydrogens already. 

 

2-bromopropane is the more stable carbocation as carbocation stability will increase as the number of hydrogens around the carbon atom increases.

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6

Name the reaction fo adding water to an alkene

Hydration reaction

7

Name the reagents, mechanism name and the organic intermediate when you have: Alkene + Water

 

Waht do you get as a product?

Alkene + H2O → Alcohol

 

Mechanism = Hydration reaction / electrophilic addition

Conditions = Heat + H3PO4 Catalyst

Reagents = Water (as steam), H3PO4 Catalyst

Organic intermediate = Alcohol

8

Name the reaction of when you add H2 to an alkene

Hydrogenation

9

Conditions for hydogenation

Nickel catalyst

423K

10

Why is 100% yield rarely achieved in organic reactions? (2)

-Transfer loss

-More byproduct is achieved than the desired product

11

How can the atom economy for the synthesis of a substance be imporved?

Reduce the number of byproducts being formed and only have the desired product forming.

12

How can percentage yield be improved?

Choose a reaction that doesn't produce many byproducts

13

Tetrafluoroethene

Common name + use

Common name = Teflon

Uses = Coating non-stick pans

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14

Phenylethene

Common name + use

Common name = Styrene

Uses = Packaging material

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15

Polypropene

Uses (2)

Used in the form of polypropene

 

Making children's toys

Fibres for ropes

16

Chloroethene

Use?

Used in the form of polychloroethene

Making PVC

17

This is a section of a polymer. What is the monomer?

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Propene

18

Probems associated with the vast quantities of plastics that are used worldwide? (4)

-Takes a long time to biodegrade

-Animals can ingest it and choke as they can't digest the plastics.

-Gets into water, pollutes the rivers/oceans

-Makes landscapes messy

19

Name the 3 alternative ways of treating the vasts amount of plastic waste that we get in our world

-PVC recycling

-Producing Potodegradable and biodegradable polymers

-Reuse of material as a feedstock for the chemical industry

20

How are addition polymers treated to allow them to be reused by the chemical industry?

They're recycled.

They're sorted into the various types of polymers and then copped into flakes, washed, dried and melted.

Recycled polymer is cut into pellets and used by manufacturers to repurpose into new products.

21

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