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Organic All Reactions for I, II & III

Organic Reactions: All 

Organic 1: 

 

Alkanes (Not on Spec)

  • Free Radical Substitution

    • Presence of UV light 

    • React with halogen to replace hydrogen atoms 

    • Halogen splits via homolytic fission 

    • Initiation (fission), Propagation (continual formation of other free radicals and substitutions o ccur), Termination (two free radicals interact)

    • Cl2 + CH4 → CH3Cl +  HCl (or multiple till CCl4)

  • Combustion with Oxygen:

    • Condition: Ignition in oxygen 

    • CH4 + 2O2 → CO2 + 2 H2O 

      • NOTE:  nitrogen in air can react in car engines for combustion leading to N2 + O2 → 2NO which is a pollutant

    • Can be incomplete which leads to CO (carbon monoxide) or C (soot) formed if there is not an excess of O2

Alkenes: 

  • Reaction with Hydrogen/Free radical Addition

    • Reagent: Hydrogen 

    • Conditions: Nickel Catalyst at 150˚C

    • Product: Alkane 

    • Reaction Type: Free radical addition (hydrogenation) 

    • Use: also used in the formation of margarine and a variety 

    • Reaction: R-C=C-R + H2 → R-C-C-R

  • Reaction with Halogens to produce Di-halogenoalkanes

    • Reagent: Halogen (Cl2, Br2, I2)

    • Conditions: room temperature and pressure

    • Observation: Goes colourless

    • Product: Di-Halogenoalkane

    • Reaction Type: Electrophilic Addition 

    • Reaction: C2H4 + Br2 → CH2Br-CH2Br

  • Reaction with Bromine Water:

    • Reagent: Bromine dissolved in water

    • Conditions: Room temperature and Pressure 

    • Observation: Decolouration 

    • Reaction Type: Electrophilic Addition 

    • RCH=CH2 + Br2(aq) → RCH(OH)CH2Br + H+ 

  • Reaction with Hydrogen Halides:

    • Reagent: Hydrogen Halides

    • Conditions: Room temperature and pressure 

    • Product Halogenoalkane 

    • Electrophilic Addition (heterolytic bond fission) - also note markovnikov's rule that the hydrogen goes the carbon which has more carbons on it as secondary carbocation is more stable and so is formed preferentially 

  • Reaction With Gaseous Water (STEAM) with an alcohol to produce an alcohol

    • Reagent: Steam, very hot water, 

    • Conditions: Alkene must be vaporised and passed over steam with an acid catalyst like phosphoric acid, H3PO4, also must be conducted in such a way that the alcohol is distilled off as the reaction is an equilibrium to prevent the rate of reaction slowing 

    • Product: Alcohol (OH attaches to 1 carbon and the H attaches to second carbon in C=C)

    • Example: R-CH=CH-R + H2O → R-CHOH-CH2-R

  • Reaction with Potassium Manganate (VII) 

    • Reagent: acidic pH Potassium manganate (VII) solution 

    • Condition: Shake at room temperature and pressure 

    • Observation: Purple solution will go colourless of brown 

    • Product: Diol 

    • Reaction Type: Oxidation 

    • Reaction: R-CH=CH-R + [O] + H2O → R-CHOH=CHOH-R

  • Polymerisation:

    • One alkene can break the pie bond in another alkene molecule and this forms the polymer 

    • This is through addition polymerisation 

    • Conditions: Heat under pressure of 1000 atm with low amounts of O2

 

Halogenoalkanes:

  • Reaction with aqueous KOH (potassium hydroxide) to produce an alcohol 

    • Reagent: Potassium/Sodium Hydroxide 

    • Conditions: Heated/Warmed under Reflux in an aqueous solution 

    • Product: Alcohol 

    • Reaction Type: Nucleophilic Substitution 

    • (OH- attacks the slight positive carbon on the haloalkane and OH- is the nucleophile this releases a halide ion)

  • Reaction with Aqueous Silver Nitrate with water as a nucleophile

    • Nucleophile: Water (lone pair on the oxygen on the water molecule → slower than OH-) 

    • First Reaction: R-X + H2O → R-OH +  H+  + X-

    • Second Reaction: X- + Ag+ → AgX  (this is the silver halide) 

    • The silver halide is a precipitate which varies in colour (NOTE: chloro react slower and iodo react faster) Colours:

      • Cl → White

      • Br → Cream 

      • I → Yellow

 

  • Reaction with Potassium Cyanide

    • Reagent: Potassium Cyanide, KCN

    • Conditions: warmed under reflux in aqueous ethanolic solution (ethanol)

    • Product: Nitrile 

    • Reaction Type: Nucleophilic Addition 

    • Reaction: R-Br + KCN → R-CN + KBr

  • Reaction with Ammonia 

    • Reagent: Excess Ammonia 

    • Conditions: Con. Ammonia at room temperature or heat in a sealed tube (if heated open the ammonia will escape)

    • Product: Amine/Aminoalkane 

    • Reaction Type: Nucleophilic substitution 

    • Reaction: R-Cl + 2NH3 → R-NH2 + NH4Cl

  • Reaction with Ethanolic Potassium Hydroxide to produce Alkenes

    • Reagent: Conc. Potassium Hydroxide in ethanolic conditions (distinction between aqueous conditions which produces an alcohol)

    • Conditions: Heat under reflux in solution of ethanol 

    • Product: Alkene 

    • Reaction Type: Elimination

    • Reaction: R-Cl + OH- → R-CH=CH2 + H2O + Cl- (or X-)

 

Alcohol: 

  • Reaction with Oxygen (Combustion)

    • Burn to form carbon dioxide and water

    • R-OH + O2 → CO2 + H2O

  • Halogenating Agents: All Substitutions 

    • Chlorinating 

      • PCl5: CH3CH2OH + PCl5 → CH3CH2Cl + POCl3 + HCl

        • Conditions: Dry alcohol 

        • Observation: White clouds of HCl fumes & some gaseous chloroalkane produced, POCl3 is also formed 

      • HCl: CH3CH2OH + HCl → CH3CH2Cl + H2O

        • Conditions: UNDER REFLUX, Excess Conc. HCl, shake until separate layers (note must be washed with sodium hydrogen carbonate to remove excess HCl) then distilled 

        • Observation: two layers

    • Brominating 

      • KBr & 50% H2SO4: KBr + H2SO4 → HBr + K2SO4 

           HBr + CH3CH2OH → CH3CH2Br + H2O 

  • Conditions: KBr & 50% H2SO4 heating under reflux 

  • 2 steps remember

  • PBr3: 3CH3CH2OH + PBr3 → 3CH3CH2Br + H3PO3

  • Iodonating

    • PI3: 3CH3CH2OH + PI3 →3 CH3CH2I + H3PO3

      • Conditions: warm a mixture of damp red phosphorus and iodine to produce the PI3 (2P + 3I2 → 2PI3). Just warm.

 

  • Reaction with Potassium Dichromate (VI) and H2SO4 

    • Reagents: Potassium Dichromate (VI) and H2SO4 

    • Conditions: Add K2Cr2O7 to hot alcohol and H2SO4 and 

    • Product: either 

      • Distil off → if primary produces aldehyde, if secondary produces ketone 

      • Reflux → if primary produces carboxylic acid, if secondary produces ketone 

    • Reaction Type: Oxidation 

  • Reaction with Phosphoric Acid to form alkene 

    • Reagent: Phosphoric (V) Acid 

    • Conditions: 2:1 ratio, heat gently (between 82˚C and 85˚C)

    • Product: Alkene 

    • ALT:

      • Pass over heated aluminium oxide 

 

Organic 2: 

 

Carbonyl Compounds: 

  • Fehlings and Benedicts and Tollens and Acidified Dichromate 

  • Aldehydes: 

    • Fehlings: Deep blue to deep red with aldehyde

    • Benedicts: Same as above 

    • Tollens: Silver Mirror with Aldehyde 

    • Potassium Manganate: Acidic conditions gives colourless and alkaline conditions gives brown precipitate 

  • Ketones:

    • Fehlings: No reaction so stays blue 

    • Benedicts: No reaction so stays blue 

    • Tollens: No reaction 

    • Potassium manganate: no reaction 

 

  • Lithium tetra hydrido aluminium oxide 

    • Reagent: LiAlH4

    • Conditions: Dry ether 

    • OR

      • Hydrogen and Platinum Catalyst, Alkenes only get reduced by this method REFER

    • Product: Ketone or aldehyde will be reduced to the secondary or primary alcohol respectively 

  • Reaction with HCN, in the presence of KCN

    • Reagent: Excess Potassium Cyanide + Some dilute sulfuric acid 

    • Conditions: pH 6-8, excess to assure enough CN- 

    • Product: Hydroxy Cyanide 

  • 2,4-DNPH

    • Aldehydes or Ketones will give you a yellow precipitate 

    • Aromatic Aldehydes and Ketones will give you an orange precipitate 

    • Filter Precipitate 

    • Conditions: Recrystallisation using hot ethanol 

    • Used to test by testing the melting temperature 

    • Yellow/orange precipitate with aldehyde and ketone 

  • Iodoform Reaction

    • Used to test for the CH3-C=O group 

    • Pale Yellow precipitate forms of iodoform 

    • Equation 

      • CH3COR + 3 I2 + 4NaOH → CHI3 + RCOONa + 3NaI + 3H2O

 

Carboxylic Acids

  • LiAlH4:

    • Reagent: LiAlH4 

    • Conditions: Dry ether 

    • Product: Primary Alcohol 

    • Equation: R-COOH + 2[H] → R-C-OH + H2O

  • Bases:

    • Reagent: Sodium Hydroxide 

    • Product: Salt 

    • Indicator: Phenolphthalein

    • Equation: R-COOH + NaOH → R-COONa + H2O 

  • Carbonates and Hydrogencarbonates:

    • Both similar reaction and observation is effervescence 

    • Equation: R-COOH + Na2CO3 → R-COONa + CO2 + H2O

    • Equation: R-COOH + NaHCO3 → R-COONa + CO2 + H2O

  •  Phosphorus (V) Chloride

    • Product: Ethanoyl Chloride 

    • Equation: R-COOH + PCl5 → R-COCl + POCl3 + HCl

    • Observation: HCl so misty fumes or if thionyl chloride used (SOCL2) SO2 formed as product

  • Alcohols with Acid Catalyst: 

    • Product: Ester 

    • Conditions: Acid catalyst such as concentrated sulfuric acid 

 

Acyl Chlorides: 

  • Water: 

    • Carboxylic Acid formed and HCl formed

    • Observation: White steamy fumes 

  • Alcohols: 

    • Product: Ester and HCl 

    • Observation: White steamy fumes 

  • Conc Ammonia:

    • Product: Amide 

    • Either forms HCl if not excess HCl which is seen as steamy fumes 

    • If excess ammonia then ammonium chloride forms which is a white smoke 

      • Note that cyclic amides can form of if the carbon chain length is long enough

  • Amines: 

    • Product: N-substituted amide

    • HCl is also produced and this is steamy fumes 

    • N-substituted is an ester with a nitrogen connecting  

  • LiALH4: 

    • Produces a alcohol and HCL 


 

Organic 3:

Carbonyl Compounds: 

  • Hydroxy Nitrile production

  • 2,4, DNPH tests for the carbonyl group 

 

Acyl Chloride: 

  • React with Water

    • Product: Carboxylic Acid 

    • Reagent: Water 

  • Reaction with Alcohols

    • Product: Ester  (can be degraded with UV light)

    • Reagent: Alcohol 

  • Reaction with Concentrated Ammonia

    • Product: Amide

    • Reagent Ammonia 

  • Reaction with an Amide

    • Product: N-substituted amide

Benzene: 

  • Halogenating: 

    • Chlorinating: Cl2 + AlCl3 + Benzene

AlCl3 acts as catalyst 

  • Brominating: Br2 + AlCl3 + Benzene 

AlBr3 as catalyst 

  • Alkylation: 

    • Haloalkane + AlCl3 Catalyst + Benzene  

  • Adding a R-CO: 

    • Acyl Chloride + AlCl3 Catalyst + Benzene 

  • Nitration: -NO2 group 

    • Concentrated HNO3 + Concentrated H2SO4

      • 2 step reaction 

      • HNO3 + H2SO4 → H2NO3 + HSO4- 

      • H2NO3+  → NO2+ + H2O 

    • This can be reduced to phenylamine 

      • H2SO4 regenerated using the hydrogen from the 

  • NOTE Ammonification 

  • Note if an ester reacts with LiALH4 the carboxylic acid part will be reduced and an alcohol group formed (from each). Even if there is a benzene ring it will not be reduced. 

  • Remember if a benzene ring is bonded to carbons which are bonded to very electronegative atoms then the group is electron withdrawing which leads to it being less reactive. 



 

Amines and Amides: 

  • Water: Forms ammonium ion and OH-

    • React with water to act as a base an form an ammonium ion and a hydroxide ion

    • E.g. butylamine + H2O → Butylammonium ion + OH-

  • Acid: forms a salt

    • More readily than with water rapidly accepts an H+ ion to form a substituted ammonium salt 

    • E.g. Butylamine + HCl → butylammonium chloride

    • Forms a whote smoke which settles as a white solid 

    • NOTE: phenylamine is only slightly soluble in water but dissolves in HCL aqueous as it reacts with H+ ions to phenylammonium which is soluble in aqueous mixture if a strong base is added the H+ is removed and the phenylamine reforms as a yellow solid

  • Halogenoalkanes: N-substituted amine 

    • REMEMBER: Amide has C=O and is like an ester while Amine is just NH2 etc.

    • A haloalkane can be attacked by an amine by the lone pair of electrons on the nitrogen of the amine this then leads to the formation of an N-substituted amine and a hydrogen ion and halide ion 

    • Forms a secondary amine 

    • Can react further to form a tertiary or quaternary ammonium salt/further N-substituted amine with multiple substitutions 

  • Ethanoyl Chloride: N substituted Amide

    • REMEMBER: Amide has C=O and is like an ester while Amine is just NH2 etc. 

    • Forms an N subs amide with a C= group from the acyl chloride 

  • Transition metals/Copper (II) ions: forms complex ions

    • Forms a complex ion as the amide acts as a ligand

    • Can be monodentate or bidentate etc. 

    • Donates a pair of electrons in doing so 

    • If the amine is added to an aqueous solution of copper (II) sulphate solution a deep blue solution is formed which is where 4 amine molecules replace r water ligands this is similar to the ammonia complex 

 

NOTE: sodium borohydride only reduces aldehydes and ketones

 

Deuterium will replace the hydrogen on the OH and the NH2 groups which influences the mass spec 

 

3 ways to make an ester:

  • Acyl chloride (HCl given off as a gas so not reversibel but highest yield) only dry ether can also be stated as anhydrous but if water added to acyl chloride then fuming HCl formed (not wanted)  

  • Carboxylic Acid + Alcohol (reversible w conc H2SO4 and reflux) not the highest yield

  • Acid anhydride + any alcohol (ester and carboxylic acid also eq so reversible and heat up ) 


 

Grignard Reagent: 

 

  • Haloalkane plus magnesium forms a grignard reagent. This can enable us carbons slightly positive carbon which can then react to act to lengthen the chain 

  • React in the presence of an Acid to form the product 

  • Methanal forms primary 

  • Longer aldehydes form secondary alcohols 

  • Ketone will form a tertiary alcohol 

  • Carbon Dioxide will form a carboxylic acid 

  • If reacted with an ester it will act to form a tertiary alcohol and the mechanism is almost like a nucleophilic addition elimination

  • The grignard will attack the carbon of this and react to form a negative oxygen (as in addition-elim) from this a grignard salt is formed and then this causes a leaving group to leave to give a ketone or aldehyde. From this point the grignard will further react to form a tertiary structure with a negative oxygen 

  • This can be reacted with any acid to provide H+ to react to give an alcohol

  • Note the grignard base can be any alkyl group 

  • If there is no leaving group such as a halide or part of an ester or anything that may leave and be stable there will be no subsequent reactions. 

  • NOTE: a grignard with water produces an ALKANE and OHMgX as the water dissociates and the H+ reacts with the negatively charged Alkyl group to form the alkane and the OH with the +MgX to give the OHMGX




 

Mechanisms:

  • The reaction mechanisms which you have covered in this course are:

    • Free radical substitution

    • Electrophilic addition

    • Nucleophilic substitution

    • Elimination

    • Nucleophilic addition

    • Nucleophilic addition-elimination

    • Electrophilic substitution

    • Formation of amides

 

  • Free radical substitution → halogen added to alkane through free radical formation

  • Electrophilic addition → Alkenes, electrophilic as ‘bond attacks the species first’ then negatively charged species formed with lone pair and this attacks carbocation. Electrophilic because the electrons from pie bond in double bond attacks the adding species first

  • Nucleophilic substitution (2) → Nucleophile attack the carbon which has a slight positive charge WHEN BONDED TO AN ATOM/ION WITH A HIGHER ELECTRONEGATIVITY. As a result carbon has a slight positive which means nucleophile (positve liking) attacks the carbon. This cause the formation of an intermediate which is unstable and thus one bonded pair will break away resulting in a substitution  (2 rate determining steps)

  • Nucleophilic substitution (1) → This occurs when a carbocation forms spontaneously as one species bonded to the carbon is more electronegative so draws electrons toward it resulting in the formation of a carbocation. A nucleophile then attacks the carbocation resulting in the substitution (only 1 rate determining step)

  • Elimination can result in the formation of the alkene or the removal of a species.. It occurs as a species with a lone pair will attack a hydrogen, such as an OH-. This hydrogen then donates electrons to the c-c bond which results in the need for one species bonded to the other carbon in the bond (that did not have the hydrogen removed). The electrons in this bond are then donated to the other species tht is bonded resulting in a double bond formation. 

  • Nucleophilic addition-elimination

  • Electrophilic substitution 

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