Topic 6-ORGANIC

• ALCOHOLS: general formula---- OH replaces an H in hydrocarbon skeleton


  Cn H2+1 OH
• ALCOHOLS: primary, secondary,tertiary

  A) C-OH

  B) 2C

  
• ALCOHOLS: isomers

  A) positions

  B) branching

  C) chain isomer

  D) positional isomer

  
• ALCOHOLS: physical properties

  A) e- increases

  B) london forces

  C) increases

  D) permanent dip-dip

  E) h- bond

  F) high

  G) hydrogen bond

  
• ALCOHOLS: Boiling point is higher for straight chain isomers, because they have bigger surface area--- so more points of contact --- stronger london forces. boiling point also increases as chain length increases, and branching increases.
• ALCOHOLS Solubility: Alcohols with low molecular Mr are miscible with water due to hydrogen bonding with water. Heavier alcohols are less miscible with water but more miscible with organic water. 


  alcohols are also good solvents --- dissolve in both polar and non- polar molecules
• REACTIONS OF ALCOHOLS: COMBUSTION

  Alcohols burn in air with a clean blue flame. C2H5OH(l) + 3O2 (g) → 2CO2 (g) + 3H2O(l)
• REACTIONS OF ALCOHOLS: COMBUSTION

  Alcohols make useful fuels. have high enthalpies of combustion.

  Advantages (compared to alkanes): do not contain sulphur so there is less pollution can be obtained from renewable resources
• OXIDATION OF ALCOHOLS

  A) aldehydes

  B) carboxylic

  C) ketones

  
• Reaction of Alcohols with Sodium

  A) H2

  B) effervescence

  C) sodium dissolves

  D) white

  
• OXIDATION OF ALCOHOLS

  A) acidified potassium dichromate

  B) aldehydes

  C) reflux

  D) ketone

  
• 1' alcohols get oxidised to form...

  aldehydes BY DISTILLATION , then carboxylic acid BY REFLUX
• OXIDATION OF PRIMARY ALCOHOLS

  A) DISTILLATION

  B) REFLUX

  C) lower

  D) condenses

  E) h2o

  F) oxidised

  
• Observation of 1' ALCOHOL: the orange dichromate ion (Cr2O7 2-) reduces to the green Cr 3+ ion
• Tertiary alcohols cannot be oxidised at all by potassium dichromate: This is because there is no hydrogen atom bonded to the carbon with the OH group
• OXIDATION OF SECONDARY ALCOHOLS. Reaction: secondary alcohol---ketone Reagent: potassium dichromate(VI) solution and dilute sulfuric acid. Conditions: heat under reflux

  A) orange

  B) green

  C) sulfuric

  
• OXIDATION OF PRIMARY ALCOHOLS TO CARBOXYLIC ACIDS:

  A) reflux

  B) ethanol

  C) K2Cr2O7 and H2SO4

  
• OXIDATION TO ALDEHYDES: DISTILLATION

  A) EXCESS

  B) SULFURIC

  C) OXIDISING

  
• HALOGENATION- CHLORINATION: substitute the –OH group for a halogen. Add solid phosphorous pentachloride to a dry alcohol at room temperature. 


  CH3CH2OH + PCl5 → CH3CH2Cl + POCl3 + HCl(g) observe misty fumes of HCl produced.
• BROMINATION Heat alcohol under reflux with KBr and 50% conc. H2SO4 to produce Br. (acid is 50% to prevent the HBr from being oxidised by the acid to bromine)


  KBr + H2SO4 → KHSO4 + HBr then CH3CH2OH + HBr → CH3CH2Br + H2O
• IODINATION Warm damp red phosphorous and iodine. This produces phosphorous trioiodide


  2P + 3I2 → 2PI3 then 3CH3CH2OH + PI3 → 3CH3CH2 I + H3PO3 The reaction of KI and conc H2SO4 can’t be used to produce HI because the sulfuric acid will oxidise the hydrogen halides to other products.
• DEHYDRATION OF ALCOHOL TO ALKENES (ELIMINATION OF WATER)

  A) elimination

  B) reflux

  C) alkene

  D) conc. phosphoric acid

  E) aluminium

  F) h2o

  
• Reaction of Alcohols

  A) oxidation

  B) elimination

  C) substitution

  D) carboxylic acid

  E) aldehyde

  F) alkene

  G) halogen

  
• Organic techniques

  A) aldehydes

  B) potassium dichromate

  C) distil

  D) orange

  E) green

  F) vent

  G) excess alcolhol + K2Cr2O7 + H2SO4

  H) alcohol, excess of K2Cr2O7 + H2SO4

  I) WATER OUT

  J) WATER IN

  K) LIEBIG CONDENSER

  L) ANTI-BUMPING

  M) CONDENSING

  N) pressure

  O) carboxylic acid

  P) excess potassium dichromate

  Q) promote smooth even boiling

  
• Tests for - OH

  • Add PCl5 to the dry test substance. All –OH give steamy fumes of HCl(g). When a glass rod dipped in concentrated ammonia is held in the fumes, a white smoke of ammonium chloride is produced • To distinguish between alcohols and carboxylic acids, test the pH. Alcohols are neutral, acids have pH < 7.
• To distinguish between 1°,2° and 3° alcohols

  Heat with a solution of potassium dichromate and sulfuric acid: • 1° and 2° turn the solution from orange Cr2O7 to green Cr3+ • 3° don’t (orange solution stays orange)
• To distinguish between 1°and 2° alcohols use Fehling’s solutions (cointain copper (II) ions) 2 Cu2+ + 2OH- (deep blue)----Cu2O (red pptate) 


  1° alcohol → aldehyde IS OXIDISED( blue to red) 2° alcohol → ketone RESIST OXIDATION(stays blue)
• Bond angles in alcohols

  A) 109.5

  B) 104.5

  C) lone pairs

  D) reduced

  E) minimum repulsion

  
• HALOGENOALKANES: Boiling point Higher than alkanes of similar chain length. Greater branching = weaker London forces ---- SMALLER SURFACE AREA, LOWER BOILING POINT. Solubility Halogenoalkanes are soluble in organic solvents but insoluble in water-- cannot H-bond
• HALOGENOALKANES- NUCLEOPHILLIC SUBSTITUTION: Halogens are more electronegative than carbon so the C-X bond becomes polar. the carbon is thus open to attack by nucleophiles
• NUCLEOPHILE IS ...
Species with a lone pair of e- used to form a convalent bond with S+ atom in another molecule.

  
• NUCLEOPHILIC SUBSTITUTION: • The nucleophile it attacks the δ + carbon atom in the halogenoalkane. • The reagent forms a bond to the C using its lone pair of electrons and the halide ion is released.

  
• Substitution reactions a) Reaction with aqueous alkali. (Na is spectator ion)

  A) reflux

  
• Nucleophilic substitution with aqueous hydroxide ions

  A) alcohol

  B) sodium hydroxyde

  C) aqueous

  D) reflux

  E) OH-

  F) elimination

  G) nucleophile

  H) full negative

  
• Substitution reactions b) Reaction with water containing silver nitrate.

  A) cold

  B) hydrolyses

  C) white, cream, yellow ppt

  D) faster

  
• reaction of halogenoalkanes with silver nitrate solution.

  A) poor nucleophile

  B) weakest

  C) hydrolyses

  D) sustitution

  E) reactive

  F) silver halide

  
• Substitution reactions c) Reaction with ammonia

  A) amine

  B) ethanol

  C) conc. ammonia

  D) sealed

  E) ammonia

  F) further substitutions

  
• NUCLEOPHILIC SUBSTITUTION: AMMONIA

  
• NUCLEOPHILIC SUBSTITUTION: POTASSIUM CYANIDE

  A) potassium

  B) ethanol

  C) water

  D) reflux

  E) nitrile

  
• ELIMINATION REACTIONS- one or more atoms are removed from adjacent carbon atoms, forming an unsaturated compund.

  A) alkene

  B) ethanol

  C) base, OH-

  D) SUBSTITUTION

  E) E-Z isomerism

  F) unsymmetrical 2' and 3'

  G) 1'

  H) 3'