Further organic chemistry
- Created by: Acacia Sheppard
- Created on: 12-06-13 09:54
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- Further organic cemistry
- Isomerism
- Structural
- E/Z (only possible with a double bond
- Optical
- Mirror images (non-superimposable)
- Always two enantiomers
- A mixture of equal volumes gives a racemate
- Used to work out reaction mechanisms
- SN1 will give a racemate, as the nucleophile can attack from either side
- SN2 will give only one enantiomer, as the nucleophile can only join to one side.
- Aldehydes and Ketones
- Don't H bond with themselves, but do with water
- Hydrogen cyanide will react by nucleophilic addition with carbonyls
- HCN dissociates and the CN- attacks the slightly positive C in C=O
- Forms a hydroxynitrile (racemic mixture shows C=O is planar and can be attacked from either side)
- Brady's reagent (2,4 DNPH in methanol and conc H2SO4) forms a bright orange precipitate with an ald or ket
- The precipitate (a dreivative of the carbonyl) is purified by recrystalisation and the melting point compared to the data book
- Tollens form a silver mirror (from a colourless solution) with ald, not ket
- Fehling's goes from blue to brick red with alds, not kets
- Reflux an aldehyde with an oxidising agent eg potassium dichromate, and a carboxylic acid will form (orage to green)
- Heat a primary alcohol with an oxidising agent to form an acid
- Reduce an ald or ket to an alcohol with LiAlH4 (nucleophilic addition)
- If it has a methyl carbonyl group, it will from a yellow precipitate when heated with iodine (CHI3) and smell like antiseptic
- Carboxylic acids
- Heat a primary alcohol with an oxidising agent to form an acid
- Reflux a nitrile (C triple bond N) with dilute HCl (hydrolysis)
- React with alkalis and carbonates to form salts and water
- Can be reduced by LiAlH4 in dry diethyl ether to an alcohol
- Mix with PCl5 to form an acyl chloride
- Add alcohol to form an ester (in the presence of an acid catalyst eg conc H2SO4)
- Reversible reaction, so product is distilled off at 80' and added to sodium carbonate. The top layer is then separated
- Esters
- Name the alcohol section first and the acid section second, but draw it the opposite way.
- Reflux with dilute acid to form the alcohol and acid (rev, hydrolysis)
- Reflux with a dilute alkali to get a carboxylate ion and alcohol (rev, hydrolysis)
- Used to make soap (heat a fat or oil with conc NaOH, then ad NaCl. The soap will crust on the surface)
- React with alcohols to make new esters (replace the alcohol section)
- Used to make margarine to avoid hydrogenation, and in making biodeisel from vegetable oils.
- Carboxylic acid + a diol make a polyester, water is eliminated
- Used in carpets, clothes fizzy drink bottles. Strong and flexible
- Acyl chlorides
- React vigorously with water to form a carboxylic acid
- React vigorously with alcohol to form an ester
- Reacts violently with ammonia to form an amide (Cl is replaced with NH2)
- Reacts violently with amines to form an n-substituted amide( Cl is replaces with NH2CH3)
- Isomerism
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