org 1 Flashcards
Halogenoalkanes react with water to produce…?
an alcohol
What is the reactivity of halogenoalkanes?
Increases down the group
Explain the experiment to determine the rate of halogenoalkanes?
Place chloroalkane,
bromoalkane and
iodoalkane into 3 test
tubes. Add silver nitrate
solution and ethanol
(solvent) to each tube. Iodide forms a yellow precipitate first
Ag^+ + I- produces AgI
Then bromine (cream), lastly chlorine (white)
This is because the halide ion gets larger down
the group and this leads to a
weaker bond.
Do halogenoalkanes have a polar bond?
yes
How do halogenoalkanes react with hydroxide ions and what are the conditions?
Nucleophilic substitution
- Under reflux
- warm aqueous sodium hydroxide
What is the reaction with cyanide ions and the conditions?
Produce nitriles
- Under reflux
- warm ethanolic potassium cyanide
What is the reaction with ammonia and the conditions?
- heat with ethanolic ammonia
- must have excess ammonia
How do you make iodoalkanes?
react iodine with PI3 (phosphorous triiodide)
- made in - situ under reflux with the alchohol red phosphorous
How can alkenes be made from alcohols?
Dehydration
- involves use of an acid catalyst either sulfuric acid of phosphorous acid
What are the products of the dehydration of non primary alcohols?
- 3 different types of alkenes
e.g - but-1-ene
- E but-2-ene
-Z but-2-ene
What does heterolytic fission form?
form 2 different ions
What does homolytic fission form?
form 2 uncharged radicals
What is the mechanism when reacting an alkane and a halogen?
free radical sub
What are the products of thermal cracking?
alkenes
What is catalytic cracking and the conditions?
- high tmperature 450 degrees
- slight pressure
- a zeolite catalyst
- products are aromatic hydrocarbons useful in fuels for vehicles.
How are alkanes reformed into cycloalkanes and aromatic molecules?
Reforming
- cyclic and branched alkanes can be made from straight chain alkanes
- A platinum catalyst
What are the producst of incomplete combustion?
carbon monoxide and carbon
What are catalytic converters?
- are mainly found in vehicles to reduce harmful pollutant entering the atmosphere.
- ## produces water vapour, nitrogen and carbon dioxide
What are sigma and Pi bonds?
Which are stronger/ weaker?
- SIgma
2 s orbitals overlap - align horizontally
- strong electrostatic attraction due to high electron denisty
Pi
- parallel overlap
- weaker as the electron density is spread out above and below the nuclei = low bond enthalpy
When do we use E/Z isomerism?
when you need to work out which compound has higher/ lower priority
What is produced in the hydration of alkenes?
- conditions
- alcohol is produced
- make ethene by
phosphoric acid catalyst and steam
