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For the best resources/ past papers please visit:
http://www.nobraintoosmall.co.nz/html/senior_chemistry/NCEA3_chemistry_organic.html
https://www.nzqa.govt.nz/ncea/assessment/view-detailed.do?standardNumber=91391
External Exam
Friday 18th November, 9:30am
5 literacy Credits
The following topics will be covered in the first 6 weeks of term 1. The 7th week will be spent revising and bringing everything from this topic together and time permitting we will have a practise exam.
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Level 2 Organics recap
(Pg 120- 134)Level 2 Organics recap
A lot of yr13 organics builds on what you did last year. I highly suggest going through the yr12 organics page on my site as well as you SciPad to refresh your memory.
Find your A3 revision sheets!
Yr12 in a nut shell:
Yr12 in a nut shell:
Naming molecules and classifying them as primary, secondary or tertiary
All of the reactions- look at the big reaction scheme!
Markovnikov's and Saytzeft's Rules
Structural and geometric isomers (cis/ trans)
M/P and B/P related to strength of bonds.
Optical Isomers
(Pg 135, 136)Optical Isomers
Optical isomers have the same formula but they are non-superimposable mirror images.
A molecule will have optical isomers if it has a chiral carbon- a carbon atom with 4 different groups attached to it. Usually identified with an *.
Optical isomers are completely identical in their physical properties apart from one. The enantiomers will rotate plane-polarized light in opposite directions.
A pair of optical isomers are called enantiomers
che_91391 enantiomers.pdfAlcohols
(Pg 146-149)Alcohols
Molecules with an-OH group, name ending in -ol.
M/P and B/P increasing with carbon chain length.
Small alcohols are polar.
As you increase the non-polar carbon chain the molecule becomes increasingly non-polar.
Distinguishing between classified alcohols.
(Pg 150, 151)Distinguishing between classified alcohols.
Using Lucas' reagent which is zinc chloride in HCl. We can work out whether an alcohol is primary, secondary or tertiary.
The tertiary alcohol will undergo the reaction quickly because it is the most stable and can happily substitute the OH with the Cl. The haloalkane is insoluble in water, hence two layers will form.
The primary alcohol will not undergo this reaction as it is unstable and hence no layers will form as an alcohol is soluble in water.
Tertiary will form 2 layers instantly.
Secondary will form in a few minutes.
Primary will do nothing.
Converting Alcohols to Chloroalkanes
(Pg 152- 154)Converting Alcohols to Chloroalkanes
Specifically going from an alcohol to a chloroalkane you can use a few different options, all of them do the same job. Either SOCl2, PCl3 or PCl5.
Fractional distillation is used to separate out two or more liquids and is used to purify the haloalkane solution. This takes advantage of its low boiling point as it will evaporate and condense down first. Leaving impurities behind.
Converting Haloalkanes to Alcohols
(Pg 158-159)Converting Haloalkanes to Alcohols
To undergo this reaction you need KOH (aq)- Yr12 Organics. However, the year 13 element is to know that this reaction needs to be done under reflux conditions.
Reflux forces an evaporated substance back into the reaction vessel. This is useful because the haloalkane has a low boiling point so it would become a gas before it has a chance to react with the KOH (aq).
Aldehydes and Ketones
(Pg 163- 165)Aldehydes and Ketones
Aldehydes and ketones are part of the carbonyl homologous series C=O. An aldehyde has the C=O on the end carbon, it's name ends in -al. A ketone has the C=O on a middle carbon, it's name ends in -one.
Reactions and preparation
(Pg165, 168, 169)Reactions and preparation
Both aldehydes and ketones are oxidised from an alcohol.
An aldehyde comes from oxidising a primary alcohol using distillation. Distillation is used so the aldehyde is removed before it continues to oxidise to form a carboxylic acid.
A Ketone comes from oxidising a secondary alcohol using reflux. Reflux is used so the alcohol cannot escape and it will continue to react.
Reminder: Oxidation requires the use of either acidified permanganate or dichromate- remember the colour changes!
Aldehyde or Ketone?
(Pg 166, 167)Aldehyde or Ketone?
There are multiple tests to distinguish between them mainly because an aldehyde can be oxidised to a carboxylic acid and a ketone cannot.
Need to know these visual results!
Properties of Aldehydes and Ketones
(pg171, 172)Properties of Aldehydes and Ketones
The melting and boiling points of these substances is relatively high. They both have temporary and permanent dipoles but do not have Hydrogen bonding.
Solubility follows the expected trend that smaller molecules will be very soluble due to the polarizing carbonyl group and as you increase the carbon chain length you decrease the solubility.
Amines
(pg 181-184)Amines
Naming molecules with an -amine ending. If is is a secondary or tertiary amine then the carbon group attached to the N is named in that manner. M/P and B/P are high as amines have temporary and permanent dipoles and Hydrogen bonding. Solubility is high for smaller molecules and as you increase the carbon chain length the solubility will decrease.
For example this molecule will be named N-methylethanamine
Carboxylic Acid and Derivatives
(pg 185,186)Carboxylic Acid and Derivatives
Carboxylic Acid
Carboxylic Acid
Named with an -oic acid. Very high M/P and B/P as it has temporary and permanent dipoles and Hydrogen bonding. Small carboxylic acids have very high solubility but as you increase the carbon chain length then the solubility will decrease.
For example this name is 2-methylpropanoic acid.
Acid Chlorides
(pg 187, 188)Acid Chlorides
Acid chlorides are formed by reacting a carboxylic acid with SOCl2. You name these molecules by ending it in -oyl chloride. M/P and B/P and solubility follow similar trends as other functional groups. An acid chloride will violently react with water, which is sometimes an exam question for identifying unknown chemicals.
For example this would be named propanoyl chloride
Amides
(pg 189-192)Amides
Acid chlorides can react with Ammonia to form an amide or with an amine to form a secondary amide. You name these molecules with an -amide ending.
For example this would be called N-methylpropanamide
Hydrolysis
(pg 193-195)Hydrolysis
Hydrolysis is when you hydrate something with water. If you are hydrating under acidic conditions then there will be an excess of hydrogen present. If it is under basic conditions then you are effectively adding OH-. The point of hydrolysis is to break one big molecule up into two smaller molecules.
Summary of carboxylic acid reactions
Summary of carboxylic acid reactions
Esters
(pg 196-203)Esters
Esters are formed by combining an alcohol with either a carboxylic acid or acid chloride. You need conc sulfuric acid as the reagent as it is a dehydrating molecule and helps remove water when the two molecules combine. They are made under reflux.
Amino Acids
(pg 205)Amino Acids
The structure of an amino acid is an organic compound which has both an amine and carboxylic functional group present. What is special about amino acids though is that they form a compound called a zwitterion. This is when the H from the carboxylic acid moves to the amine group to make a negatively charge O and a positively charged N. This highly polar molecule forms very strong bonds due to these charges.
Polymers
(pg215- 222)Polymers
Polymers are long chain molecules made up of repeating units called monomers. The polymer can be broken up via acidic or basic hydrolysis. You just have to think about where the smart place to split the molecule up would be to put an OH on one side and an H on the other (H2O)
Addition Polymers
(pg215)Addition Polymers
This is from Yr12. This is when a molecule which has a double bond, breaks that double bond and adds repeating units of itself together. You usually require heat and catalyst for the reaction to proceed.
Condensation Polymers
(pg216-219)Condensation Polymers
This polymer is made when two molecules come together and a small molecule (either H2O or HCl) is removed. This can cause polymers if there is more than 1 reactive site. This reaction will also need heat and a catalyst present in order to proceed.
A3 Revision Sheets
A3 Revision Sheets
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