Module 6 - Definitions

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Benzene
C6H6, a colourless, highly flammable liquid, classified as a carcinogen.
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Kekule Model Of Benzene
Suggested that benzene was a six carbon compound with alturnative double and single bonds
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Evidence to Disprove Kekule Model Of Benzene
1. Benzene is stable (doesn't decolourise bromine water 2. The length of bonds are the same 3.Has a lower bond enthalpy than suggested
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Delocalised Model of Benzene
1. Planar, cyclical, hexagonal hydrocarbon 2.Overlapping adjacent p-orbitals. form ring of electron density above and below plane 3.Delocalised pi-bonds are formed by overlapping orbitals
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Electrophile
An atom which is attracted to a electron-rich atom, where it accepts a pair of electrons to form a covalent bond
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Electrophilic Substitution
A type of substitution reaction in which a electrophile is attracted to a electron-rich atom, where it accepts a pair of electrons to form a covalent bond
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Nitration Of Benzene
Benzene reacts with nitric acid at 50c, with a sulfuric acid catalyst to add one -NO2 group. If temp is higher produces dinitrobenzene. (Mechanism)
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Halogenation Of Benzene
At RTP with a halogen carrier (FeBr3/FeCl3) benzene bects with a halogen, to form a halogenbenzene and H(halogen) (Mechanism)
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Alkylation of Benzene
The substituton of H in the benzene ring by a alkyl group, using a haloalkane and a friedel-crafts catalyst
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Acylation of Benzene
Benzene reacts with a acyclchloride with a AlCl3 catalyst, in a electrophillic substitution reaction, formsa phenyl compound
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Comparing the reactivity of Benzene and alkene
Benzene is less reactive than alkenes. This is because the delocalised pi-bond has a lower electron density than the localised C=C bond. When a polar molecule approaches there's insufficient density to polarise bromine.
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Phenol
C6H5OH, has a -OHgroup attached to a benzene ring which influences the reactions it undertakes
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Phenol as a Weak Acid
Is less soluble in water than alcohols due to the non-polar benzene. Phenol is more reactive thanalcohols but less reactive than carboxylic acids.
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Bromination of Phenol
Phenol rects with Br(aq) to form a white precipitate. This reaction decolourises the bromine water. No catalyst
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Nitration of Phenol
Phenol rects readily with diute nitric acid at RTP to form 2-nitrophenol and 3-nitrophenol
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Comparing the Reactivity of Phenol and Benzene
Phenol is more rective than bezene. This is because the lone pair of e- on the oxygen is donated to the pi-bond, increasing the electron density. So the electrophile is more susceptable to attack for phenol than benzene
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Carbonyl
Aldehydes and ketones both contain the carbonyl group C=O
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Aldehyde
The carbonyl group is on the end of the C chain. The structural formula is CHO
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Ketones
The carbonyl group is joined within the C chain. The structural formula is CO
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Oxidation of Aldehydes
Can be oxidised into carboxylic acids under eflux with potasium dichromate and H2SO4
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Nucleopile
An atom which is attracted to a electron-deficient atom, where it accepts a pair of electrons to form a covalent bond
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Nucleophillic Addition
A nucleophile is added to an atom with a electron-deficient atom, where it accepts a pair of electrons to form a covalent bond
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Why carbonyls undergo Nucleophillic Addition?
The C=O bond in a carbonyl is polar, becaus ethe oxygen is more electronegative than C.The polarity attracts nucleophiles, which attack the slightly positive C resulting in a addition
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Reactions of Carbonyls withNaBH4
Aldehydes are reduced to form primary alcohols. Ketones are reduced to form secondary alcohols
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Reactions of Carbonyls with HCN
Ketones react with HCN to form a hydroxynitrile. This is a nucleophillic addition reaction (mechanisms)
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Testing for a Carboxyl group
2,4-DNP is added in excess into a testube. Add a few drops of the unknown solution, if a orange precipitate forms a carbonyl group is present
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Distinguishing between a Aldehyde and Ketone
Pour equal volumes of Tollens reagent and the unknown solution into a test tube and warm above 50c, if a silver precipitate forms a aldehyde is present. This is because the aldehyde is oxidised forming a carboxylic acid and silver ions are reduced
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Solubility of Carboxylic Acids
The C=O and O-H bonds are polar, so form hydrogen bonds with water, so carboxylic acids are soluble. As the C increases solubility decrease, as the overall polarity falls.
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Reactions of Carboxylic Acids with metals
Aqueous COOH do a redox reaction with metals to form a carboxylate salt and H2
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Reactions of Carboxylic Acids with Metal Oxides
Neutralisation: Form a salt and water
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Reactions of Carboxylic Acids with Alkalis
Neutralisation: Form a salt and water
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Reactions of Carboxylic Acids with Carbonates
Neutralisation: Form a salt, water and carbon dioxide
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Test for a Carboxyl Group
Reactions of Carboxylic Acids with Carbonates form a white precipitate to distinguish a carboxyl group
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Esterification
The reaction of a warm alcohol with a carboxylic acid to form a ester and water with a H2SO4 catalyst (name:alcohol carboxylic acid)
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Acid Hydrolysis of Esters
Ester is heated under reflux with dilute aqueous acid. The ester is broken down witrh water to form a carboxylic acid and alcohol
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Alkaline Hydrolysis of Esters
The ester is heated under reflux with aqueous OH- to form a carboxylate ion and alcohol
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Preparation of Acyl Chlorides
Carboxylic acid + SOCl2 = Acyl Chloride +SO2 +HCl
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Reaction of Acyl Chlorides with Alcohols
Acyl Chloride + primary alcohol = Ester + HCl
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Reaction of Acyl Chlorides with Phenol
Acyl Chloride + Phenol = ester and HCl
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Reaction of Acyl Chlorides with Water
Acyl Chloride + Water = Carboxylic Acid + HCl
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Reaction of Acyl Chlorides with Ammonia
Acyl Chloride + Ammonia = Primary Amide + NH4Cl. Ethanol is used as a solvent to prevent subtitution of water
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Reaction of Acyl Chlorides with a Primary Amine
Acyl Chloride + Primary Amine = Secondary Amide + ammoniumchloride
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Aliphatic Amine
The N is attached to one straight or unbranched C chain
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Aromatic Amine
The N is attached to a aromatic ring
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Primary Amine
The N is attached to one R-group
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Secondary Amine
The N is attached to two R-groups
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Tertiary Amine
The N is attached to three R-groups
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Amines as Bases
The lone electron pair on the N means that amines can form a dative covalent bond with a proton
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Preperation of Aromatic Amines
Reduce nitrobenzene with Sn, con HCl and excess NaOH to form a aromatic amine and water
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Amino Acids
A organic compound with a amine group (NH2) and a carboxyl group (COOH)
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Reaction of Amino Acids and Acids
The amine group acts as a base so forms a salt with any acid
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Reaction of Amino Acids and Alkali
The carboxyl group acts as a acid, so reacts with a alkali to form a salt
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Reaction of Amino Acids and Alcohols
Amino acids, undergo esterification when heated with a alcohol with a H2SO4 catalyst (The carboxyl group)
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Stereoisomers
Compounds with the same structural formula but a different arrangement of atoms
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Optical Isomers
Found in chiral centres, leading to two non-superimposable mirror image structures
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Chiral Atom
A atom with four different atoms or group of atoms (Draw 3-D structures)
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Condensation Polymer
The joining of monomers with the loss of a small molecule, usually with the loss of a small molecule
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Polyester
Monomers are joined together by ester linkages in a long chain to form a polymer. Can be made from a COOH and OH groups (O=C-O)
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Polyamide
Monomers are joined together by amide linkages in a long chains. These can be from a -COOH and -NH2 (O=C-N-H)
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Hydrolysis of Polyesters
Base: Forms a salt and alcohol. Acid: Forms a alcohol and carboxylic acid
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Hydrolysis of Polyamides
Base: Forms a carboxyl salt and amine group compound. Acid: Forms a carboxylic acid and NH3 compound
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Nitriles (CN) from Haloalkanes
Reacting haloalkanes with NaCN/KCN in ethanol to increase carbon chain leaving the halogen ion (mechanism)
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Nitriles (CN) Aldehydes and Ketones
Reacting a carboxyl with HCN with a sulfuric acid catalyst forming a hydroxynitrile (mechanism)
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Reduction of Nitriles
Nitriles can be reduced to form a amine, in the presence of a nickel catalyst
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Hydrolysis of Nitriles
Nitriles can be hydrolysed to form carboxylic acids by heating with dilute HCl
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Seperating a Solid from a Solvent
FILTRATION UNDER REDUCED PRESSURE - Connect a buchner flask to a buchner funnel,switch on vacuum pump, place a filter paper with the solvent used and pour sample to separate.
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Recrystalisation
Disolve the impure sample with the minimum volume of warm solvent . Allow to cool and crystals form, filter under reduced pressure to get crystals
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Chromotography
Separates a compound out into its constituent elements
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Thin Layer Chromotography (TLC)
Spot a small amount of solution onto the drawn base line. Add a small volume of solvent in a beaker add the TLC plate, and place watch glass on top. Leave it to rise, mark solvent front and components would separate out into its elements
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Other cards in this set

Card 2

Front

Suggested that benzene was a six carbon compound with alturnative double and single bonds

Back

Kekule Model Of Benzene

Card 3

Front

1. Benzene is stable (doesn't decolourise bromine water 2. The length of bonds are the same 3.Has a lower bond enthalpy than suggested

Back

Preview of the back of card 3

Card 4

Front

1. Planar, cyclical, hexagonal hydrocarbon 2.Overlapping adjacent p-orbitals. form ring of electron density above and below plane 3.Delocalised pi-bonds are formed by overlapping orbitals

Back

Preview of the back of card 4

Card 5

Front

An atom which is attracted to a electron-rich atom, where it accepts a pair of electrons to form a covalent bond

Back

Preview of the back of card 5
View more cards

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