Org. Chemistry Reactions Flashcards
Heating ALKENE with H2 gas and Pt/Ni catalyst:
Alkane
Producing ALKANE from ALKENE
Hydrogenation by heating ALKENE with H2 gas and Pt/Ni catalyst
Complete combustion of ALKANE
… + O2 -> CO2 + H2O
Incomplete combustion of ALKANE
… + O2 -> CO + H2O
Producing HALOGENOALKANE from ALKANE
Free-radical substitution using UV light
Catalytic removal of carbon monoxide using oxygen
2CO + O2 -> 2CO2
CO oxidised into CO2
Catalytic removal of carbon monoxide and nitrogen
2CO + 2NO -> 2CO2 + N2
NO/NO2 reduced into N2
Catalytic removal of unburnt ALKANES
CnH2n+2 + (3n+1) [O] -> nCO2 + (n+1) H2O
Oxidation of alkane into CO2 and H2O
What does homolytic fission form?
2 free-radicals
What does heterolytic fission form?
1 cation and 1 anion
Producing halogenoalkane from ALKENE
Electrophilic addition of hydrogen halide (HX) or halogen (X2)
Process of electrophilic addition of hydrogen halide (HX) to ALKENE
- Electrons in the double bond attack the partially positive hydrogen (electrophile), forming C-H bond by donating the electrons.
- The negatively charged X (nucleophile) attacks the carbocation formed, forming C-X bond with the most substituted carbon atom.
Product: CnH2n+1X
Process of electrophilic addition of halogen (X2) to ALKENE
- Double bond induces a dipole on the X2 by repulsing electrons away from the closer X.
- Double bond electrons attack the partially positive X, forming C-X bond.
- Negatively charged X left behind attacks the carbocation formed, forming C-X.
Product: CnH2nX2
Reaction between alcohol and hydrogen halide (HX)
Substitution.
Forms halogenoalkane (CnH2n+1X) and water.
Reaction between alcohol and PCl3, heated
Substitution.
Forms halogenoalkane (CnH2n+1X) and phosphorus acid (H3PO3)
Reaction between alcohol and PCl5
Substitution.
Forms halogenoalkane (CnH2n+1X), hydrochloric acid (HCl) and phosphorus oxychloride (POCl3).
Reaction between alcohol and SOCl2
Substitution.
Forms halogenoalkane (CnH2n+1X), hydrochloric acid (HCl) and sulphur dioxide (SO2)
Define primary, secondary and tertiary halogenoalkane
Primary: carbon bonded with 2 hydrogen
Secondary: carbon bonded with 1 hydrogen
Tertiary: carbon bonded with no hydrogen
Reaction between halogenoalkane and NaOH(aq)
Substitution (hydrolysis).
Halogen atom replaced with OH.
Forms: alcohol and negatively charged halogen
Reaction between halogenoalkane and AgNO3(aq)
Substitution (hydrolysis).
Halogen atom replaced with OH.
Forms: alcohol and negatively charged halogen
Does NaOH(aq) react faster than AgNO3(aq) with halogenoalkane? Explain.
Yes, NaOH reacts faster because it is an alkali that donates OH- easier than water, which is only partially negative.
Reaction between halogenoalkane and ethanolic KCN
Substitution.
Halogen atom replaced by CN.
Forms nitrile and negatively charged halogen.
Reaction between halogenoalkane and ethanolic NH3 in excess
Substitution.
Halogen atom replaced by NH3, forming alkylammonium and negatively charged halogen.
One hydrogen atom is attacked by nucleophilic halogen, forming alkylamine and hydrogen halide.
Reaction between halogenoalkane and ethanolic NaOH, heated
Elimination.
Heterolytic fission between C-X, forming negatively charged Br.
Forms alkene, sodium halide and water.
Process of SN2 in halogenoalkane
Occurs in primary halogenoalkane.
1. Nucleophile attacks partially positive carbon C-X, electrons from the bond move to X.
2. Forms an intermediate, bond with X breaks and bond with nucleophile forms.
3. Produces alcohol and negatively charged halogen.
Process of SN1 in halogenoalkane
Occurs in tertiary halogenoalkane.
1. C-X breaks heterolytically, forming a carbocation and a negatively charged halogen
2. Nucleophile attacks carbocation
3. Forms alcohol and negatively charged halogen
Precipitate of AgNO3 added to Cl
AgCl, white precipitate, appears slowest
Precipitate of AgNO3 added to Br
AgBr, cream precipitate, appears slightly slow
Precipitate of AgNO3 added to I
AgI, yellow precipitate, appears the fastest
Producing ALKENE from halogenoalkane
Elimination.
Heated with ethanolic NaOH.
Produces alkene, water and sodium halide
Producing ALKENE from alcohol
Dehydration.
Heated with Al2O3 powder.
Produces alkene and water
Producing ALKANE from ALKENE
Electrophilic addition (hydrogenation)
Heated with Pt/Ni catalyst.
Producing alcohol from ALKENE
Electrophilic addition (hydration)
Heated with H3PO4 and steam
Producing halogenoalkane (CnH2n+1X) from ALKENE
Electrophilic addition.
At room temperature, with hydrogen halide
Producing halogenoalkane (CnH2nX2) from ALKENE
Electrophilic addition.
At room temperature, with halogen
Reaction of ALKENE with cold, dilute KMnO4
Alkene oxidised into diol.
Pale purple -> Colourless
Reaction of ALKENE with hot, concentrated KMnO4
(CH2, CHR, CR2)
Oxidation.
CH2 -> CO2
CHR -> aldehyde (CH=O) -> carboxylic acid (C=OOH)
CR2 -> ketone (C=O)
Process of electrophilic addition in ALKENE (e.g C2H4 + HBr)
- Double bond’s electrons attack electrophile, forming bonds between them and breaking bonds between H-Br
- Carbocation formed, negative Br attacks and bonds
How is Br2 made polar in electrophilic addition of Br2 to ALKENE?
Induced dipole caused by high density of electrons in the double bond, repelling electrons from the Br closest.
What is a test for double bonds?
Adding Br2 (orange-brown)
If turns colourless, double bond present.
If no change, double bond NOT present.
How is alcohol formed from ALKENE?
Hydration using steam and H3PO4.
C2H4 + H2O -> C2H5OH
How is alcohol (diol) formed from ALKANE?
Oxidation using cold, dilute KMnO4.
C2H4 + H2O + [O] -> C2H4(OH)2 (ethanediol)
How is alcohol formed from halogenoalkane?
Heating with NaOH (aq).
C2H5Br + NaOH -> C2H5OH + NaBr
How is alcohol formed from aldehyde or ketone?
By reducing with NaBH4 or LiAlH4.
C2H4OH + 2[H] -> C2H5OH
C3H6O + 2[H] -> C3H7OH
Which is a strong reducing agent, NaBH4 or LiAlH4?
LiAlBH4
How is alcohol formed from carboxylic acid?
By reducing with LiAlBH4.
CH3COOH + 4[H] -> C2H5OH + H2
How is alcohol formed from ester?
By hydrolysis with dilute acid or alkali.
Ethyl ethanoate + H2O -> ethanoic acid + ethanol
Ethyl ethanoate + NaOH -> sodium ethanoate + ethanol
Reaction between alcohol and hydrogen halide.
Substitution. Forms halogenoalkane and water
Reaction between alcohol and KBr + H2SO4/H3PO4
Substitution. Forms halogenoalkane and water
Reaction between alcohol and PCl3
Substitution. Heated. Forms halogenoalkane and H3PO3.
Reaction between alcohol and PCl5
Substitution. Room temperature. Forms halogenoalkane, HCl and POCl3.
Reaction between alcohol and SOCl2
Substitution. Forms halogenoalkane, HCl and SO2.
Reaction between alcohol and sodium
Forms sodium alkoxide and H2. Removal of H from OH, forming O- which attracts Na+
Oxidation of primary alcohol
Removes 2H to form aldehyde. Removes 1H and adds 1O to form carboxylic acid.
Oxidation of secondary alcohol
Removes 2H to form ketone.
How is ALKENE formed from alcohol?
Dehydration using Al2O3.
C2H5OH -> C2H4 + H2O
How is ester formed from alcohol?
Esterification using H3PO4 or H2SO4.
C2H5OH + CH3COOH -> CH3COOC2H5 + H2O
How are esters named?
Alkyl (from alcohol) alkynoate (from carboxylic acid)
How does K2Cr2O7 react with primary, secondary and tertiary alcohol?
Primary & secondary is oxidised, reducing K2Cr2O7. CC from orange to green.
Tertiary can not be oxidised, stays orange.
What is the interaction between iodoform and alcohols?
Alcohol is first oxidised into methyl ketone.
Methyl ketone is halogenated and then hydrolysed to form sodium salt and tri-iodomethane (CHI3) which gives it the yellow precipitate.
What is the colour change when K2Cr2O7 oxides alcohol?
Orange to green
What is the colour change when KMnO4 oxidises alcohol?
Purple to colourless
Process of aldehyde synthesis
Warm primary alcohol is slowly added to an oxidising agent (K2Cr2O7 OR KMnO4). Aldehyde can be distilled off, as it has a lower boiling point than alcohol, condensed into a liquid and collected.
How is aldehyde formed from alcohol?
Oxidising PRIMARY alcohol with K2Cr2O7 or KMnO4.
Process of ketone synthesis
Warm secondary alcohol is slowly added to an oxidising agent (K2Cr2O7 or KMnO4). It is not further oxidised so it does not need to be distilled right after forming.
How to form alcohol from aldehyde?
Aldehyde is reduced (NaBH4 or LiAlH4) into primary alcohols.
How is alcohol formed from ketones?
Ketones are reduced (NaBH4 or LiAlH4) into secondary alcohols.
Reaction between aldehyde and HCN
Nucleophilic addition (CN- as the nucleophile)
- CN- attacks the carbonyl carbon, forming a negatively charged intermediate (CH3CH(O-)CN)
- Protonation of HCN by O- from the carbonyl, forming hydroxynitrile (e.g CH3CHOHCN)
*C=O bond is polarised, O being more electronegative and drawing electron density towards itself, making it slightly negatively charged.
Aldehyde and ketone reaction with 2, 4-DNPH
Condensation reaction. Forms a deep orange precipitate and water
Fehling’s solution reaction with aldehyde
Warmed. Aldehyde is oxidised to a carboxylic acid, Cu2+ ions in Fehling’s solution is reduced to Cu+.
The carboxylic acid is neutralised by alkali, into -COO(-) and forms a salt with a metallic cation (e.g Na+)
CC from clear blue solution into a red opaque precipitate due to copper(I) oxide
Does ketone give a positive result with Fehling’s solution?
No because it can’t be oxidised.
Tollens’ reagent reaction with aldehyde
Aldehyde is oxidised into a carboxylic acid, reducing the Ag+ into Ag. Carboxylic acid form carboxylate ions and salt under alkaline conditions.
CC into silver ‘mirror’ due to reduction of Ag+
What does iodoform react with?
CH3CO- in methyl ketones, secondary alcohol and ethanal
How are carboxylic acids formed from alcohol?
Oxidation of PRIMARY alcohol into aldehyde and then further oxidation into carboxylic acid with acidified K2Cr2O7 or KMnO4 and reflux
How are carboxylic acids formed from aldehydes?
Oxidation with acidified K2Cr2O7 or KMnO4 with reflux
How are carboxylic acids formed from nitriles?
Hydrolysis of nitrile (the C-N is converted into COOH)
Using dilute acid forming carboxylic acid and ammonium salt.
Using dilute alkali, forming sodium carboxylate salt and ammonia. Acidification changes the carboxylate ion into a carboxylic acid
How are carboxylic acids formed from ester?
Hydrolysis
By dilute acid, a reversible reaction to form an alcohol and carboxylic acid.
By dilute alkali, a irreversible reaction that forms an alcohol and sodium carboxylate salt, acidification changes the carboxylate ion into carboxylic acid.
Reaction between carboxylic acid and reactive metals
Redox
CH3COOH + Na -> CH3COO-Na+ + H2
Forms sodium salt (sodium -oate) and hydrogen gas
Reaction between carboxylic acid and alkali
Neutralisation
Forms sodium salt (sodium -oate) and H2O
Reaction between carboxylic acid and carbonates
Acid-base
2CH3COOH + Na2CO3 -> 2CH3COO-Na+ + H2O + CO2
Forms sodium salt, water and carbon dioxide
Reaction between carboxylic acid and alcohol
Esterification using H2SO4 catalyst
Forms ester and water
Reaction between carboxylic acid and LiAlH4
Reduction
Forms primary alcohol and water
How is ester produced?
Condensation reaction between carboxylic acid and alcohol with H2SO4 catalyst. Also produces water
How to break down ester?
Hydrolysis in a reversible reaction with H2SO4 catalyst, forming carboxylic acid and alcohol.
Alternatively, heating ester under reflux with dilute alkali is irreversible, forming sodium carboxylate salt and alcohol. Further acidification of sodium carboxylate forms carboxylic acid.
How to form amine from halogenoalkane?
Nucleophilic substitution. Heated under pressure with ethanolic ammonia.
Forms alkylammonium (e.g CH3CH2NH3) and halogen ion.
Negative halogen attracts one of the H, forming HX and alkylamine (e.g C2H4NH2)
How are nitriles formed from halogenoalkanes?
Nucleophilic substitution of the halogen. With ethanolic KCN heated under reflux. CN- acting as the nucleophile. Forms nitrile and potassium halide. *CN adds an extra carbon to the carbon chain
How are hydroxynitriles formed from aldehydes and ketones?
Nucleophilic addition using HCN. CN- as the nucleophile, attacking the carbon in C=O.
Followed by protonation of O- when it takes most of the electron density.
How are nitriles broken down?
Hydrolysis by dilute acid or dilute alkali followed by acidification.
Dilute acid forms carboxylic acid and ammonium salt.
Dilute alkali forms sodium carboxylate salt and ammonia, acidification changes the carboxylate ion into carboxylic acid.