Question | Answer |
Ethanoic acid with NaOH. Products? | Sodium Ethanoate and water; remember to NOT show the charges on the Sodium Ethanoate |
Ethanoic acid with NaOH. what are the conditions? | room temperature |
Carboxylic acid with Sodium carbonate.Products? | Sodium Ethanoate, water and carbon dioxide |
what are the observations? | colourless gas produced can turn limewater cloudy (this is the test for carboxylic acids) |
Ethanoic acid with Sodium Carbonate. What are the conditions? | room temperature |
How do you convert a carboxylate salt back to a carboxylic acid? (reagents) | Dilute HCl |
How do you convert a carboxylate salt back to a carboxylic acid? what are the conditions? | room temperature |
Esterification. what are the reagents? | alcohol with carb acid with CONC. H2SO4 |
Esterification. what are the conditions? | Heat under reflux |
Products of Hydrolysis of Ethylmethanoate with dil HCl? | Ethanol and Methanoic Acid |
Products of Hydrolysis of Ethylmethanoate with dil NaOH? | Ethanol and SodiumMethanoate |
what are the conditions for the Hydrolysis of Esters? | heat under reflux |
What is the reagent to convert Propanal into Propanoic acid? | ACIDIFIED (conc H2SO4) K2Cr2O7 |
What is the reagent to convert Propanal into Propanoic acid? | heat under reflux |
A carbonyl compound is placed with potassium dichromate and conc. H2SO4. The colour of the mixture turns from orange to green. What is your inference? | The compound has been oxidised; the compound must be an aldehyde |
How do you distinguish between aldehydes and ketones? (reagents, conditions and observation) | Tollens reagent creates a silver mirror from a colourless solution.OR Fehlings solution, heated, turning from blue to brick red precipitate |
How do you convert Propanal to Propanol? (reagents, conditions) | NaBH4 with heat |
What is the product when Propanal reacts with HCN? | 2-Hydroxy Propane Nitrile |
What type of reaction: Carbonyl with HCN? | Nucleophilic Addition |
What type of reaction: Aldehyde into Carboxylic Acid? | Oxidation |
What type of reaction: Aldehyde into Alcohol? | Reduction |
What is the product of the reaction between an Acyl Chloride and Ammonia? | Amide and HCl |
What is the product of the reaction between an Acyl Chloride and an Amine? | Amide and HCl |
What is the product of the reaction between an Acyl Chloride and an Alcohol? | Ester and HCl |
What observation during acylation? | Misty fumes |
CHALLENGE: evaluate the use of Acyl Chloride vs Anhydrides and Carboxylic acids to produce esters | Acyl Chloride do not require heating to require (saves energy) BUT Acyl chloride produce acidic fumes that will need neutralising; Anhydrides are best (room temp but no acidic fumes) |
Write the equation for the oxidation of CH3CH(OH)CH3 using [O] | CH3CH(OH)CH3 + [O] --> CH3COCH3 + H2O |
Write the equation for the oxidation of CH3CH2CH2OH using [O], under reflux | CH3CH2CH2OH + 2 [O] --> CH3CH2COOH + H2O; the propan1ol is oxidised TWICE |
Write the equation for the oxidation of CH3CH2CH2OH using [O], when distilling | CH3CH2CH2OH + [O] --> CH3CH2CHO + H2O |
Write the equation for the reduction of CH3CH2CHO using [H] | CH3CH2CHO + 2[H] --> CH3CH2CH2OH |
Write the equation for the reduction of CH3COCH3 using [H] | CH3COCH3 + 2[H] --> CH3CH(OH)CH3 |
CHALLENGE: evaluate the use of NaBH4 as a reducing agent compared to H2/Ni | NaBH4 reduces selectively ONLY carbonyls; H2/Ni reduces carbonyls; alkenes; aromatic compounds |
Write the equation for the nucleophilic addition of CH3COCH3 with HCN | CH3COCH3 + HCN --> CH3C(OH)(CN)CH3 |
Write the equation for the nucleophilic addition of CH3CH2CHO with HCN | CH3CH2CHO + HCN --> CH3CH2CH(OH)(CN) |
Describe the mechanism of Nucleophilic Addition of NaBH4 onto a carbonyl | 1)show lone pair on H- and polarised C=O; 2) attack of lone pair onto the partially positive C (ensure arrows touch at start and end) 3) C=O bond fold onto O; 4) redraw as you see 5lone pair on O- attacks H from H2O 5) polarised H-O from water folds |
Describe the mechanism of Nucleophilic Addition of HCN onto a carbonyl | 1)show lone pair on C from CN- and polarised C=O; 2) attack of lone pair onto the partially positive C (ensure arrows touch at start and end) 3) C=O bond fold onto O; 4) redraw as you see 5) lone pair on O- attacks H+ |
Write the equation for the reaction between CH3COOCH2CH3 and HCl | CH3COOCH2CH3 + HCl --> CH3COOH + CH3CH2OH |
Write the equation for the reaction between CH3COOCH2CH3 and NaOH | CH3COOCH2CH3 + NaOH --> CH3COONa + CH3CH2OH |
Write the equation for the reaction between ethanoic anhydride CH3COOCOCH3 and CH3CH2OH | CH3COOCOCH3 + CH3CH2OH --> CH3COOCH2CH3 + CH3COOH |
Write the equation for the reaction between CH3COOH and CH3CH2OH (with Conc H2SO4) | CH3COOH + CH3CH2OH --> CH3COOCH2CH3 + H2O |
Write the equation for the reaction between CH3COCl and CH3CH2OH | CH3COCl + CH3CH2OH --> CH3COOCH2CH3 + HCl |
CHALLENGE: How to distinguish between primary, secondary and tertiary alcohols? | add potassium dichromate (vi) acidified with dilute h2s04; if no observation: orange ––––> green then tertiary; do fehlings/tollens on the distilled products of oxidation |
CHALLENGE: Explain the trend in boiling point of an alkane, carbonyl compound and an alcohol of similar RMM | similar RMM so vdw imf dont influence the boiling point; carbonyls: they have polar c=o, hence they have permanent dd im forces which increases bp; Alcohols can H bond between molecules, therefore they have a higher bp than both alkanes and carbonyls. |
Why are carbonyls soluble in water? | They can form H bonds with water |
CHALLENGE: Explain the trend insolubility with increasing chain length of a carbonyl compound | As chain length increases, molecule becomes dominated by the hydrocarbon chain/ the VdW forces between the molecules become stronger than the H-bond, hence the c=o group becomes a smaller portion of the molecule, hence it becomes less soluble in water. |
Explain why is the high mean bond enthalpy of c=o surprising | Because high mean bond enthalpy suggests that it is unreactive, however c=o is polar hence it is reactive. |
Explain why NaBH4 is a selective reducing agent | NaBH4 will reduce c=o but not c=c, this is because the hydride ions provided by NaBH4 arent attracted to the region of high electron density around the c=c (like charges repel). However, the hydride ions are attracted to the delta +ve carbon on the c=o. |
Why can't you use HCN as a reagent for nucleophillic addition with a cyanide ion? | HCN is a toxic gas that binds irreversibly with the haemoglobin in place of oxygen and hence prevents aerobic Respiration. It is also a weak acid so only partially dissociates, hence doesn't provide enough H+ |
What reagent and conditions do you use instead of HCN for nucleophillic addition? | reagents: KCN OR NaCN; Conditions: dilute acid (hcl) to provide H+. |
1)Why is nucleophillic addition with a cyanide ion useful? 2)What is the problem for the chemist with the products? | 1) It can lengthen the carbon chain 2) It can lead to the production of two optical isomers which are difficult to separate |
CHALLENGE: During nucleophilic addition, two optical isomers are produced, yet the mixture is optically inactive. Explain why | Equal probability of the nucleophille attacking from above or below the planar c=o. So racemic mixture forms: theres is equal amounts of both enantiomers present, each rotate the plane of polarisation of light by equal amounts in opposite directions. |
What is the test for a carboxylic acid? | Add sodium hydrogen carbonate: if there is a carboxylic acid present you will observe effervescence due to the production of Co2. |
What is the equation for esterification and what are the reagents and conditions for this reaction? | alcohol + carboxylic acid < = > ester + H2O reagents: CONCENTRATED H2SO4 or CONC HCl conditions: warm, 50–60, conc h2s04/hcl acid catalyst |
CHALLENGE Explain why esterification have to have a warm temp of 50–60? (3 reasons) | 1) Increased rate: more successful collisions\n2) increased yield: forward reaction is endothermic 3) Practical: Ester more likely to evaporate hence you can smell it easier. |
What is the problem of producing esters by esterification and what is the alternative method? | The reaction is reversible hence doesnt go to completion thus meaning there is a low yield. You can also produce an ester via acylation |
What the the three uses of esters? (and why they are used for these things) | 1) solvents (pd-pd imf hence since like dissolves like they dissolve other molecules) 2) plasticisers (added to plastics during polymerisation to make them more flexible/ reduce effects of im forces between chains) 3) food flavourings/perfumes |
1)Why is base hydrolysis more favourable? 2)What is the one problem with it and how is it solved? | 1) the reaction goes to completion hence the yield is higher than the other which is a reversible reaction 2) it produces a carboxylate ion(+alcohol) instead of a carboxylic acid. Add excess h2s04 to turn carboxylate ion into carboxylic acid product |
Describe how to draw the structure of an oil or a fat | The E as a coat hanger; add C=O; add three fatty acid chains = TRIGLYCERIDE |
What is the (word) equation for hydrolysis of a triglyceride? | triglyceride + 3NaOH –––> 3xcarboxylate salts + glycerol |
What can the mixture of carboxylate salts produced during hydrolysis of fats be used as? | The mix of carboxylate salts can be used as soap |
Describe how the mixture of carboxylate salts works as soaps/ cleaning agents | They are ionic salts : Na+ and the –salt. The hydrocarbon chain on salt has weak VdW imf which allow it to bind with grease.The COO–/ ionic/polar head binds with H2O. Therefore the whole salt allows water and grease to mix= good cleaning agent |
What are the properties of glycerol and what is it used for ? | It has an –OH group so can hydrogen bond with water/is very soluble in water. It is used in cosmetics/creams/ointments/makeup because it forms H-bond with water easily and prevents the cream from drying out. Also used in toothpaste. |
Describe how biodiesel is manufactured | Extracted from natural ester (rape seed oil from plant): triglyceride + 3CH3OH –––> glycerol + biodiesel THIS IS NOT HYDROLYSIS OR ESTERIFICATION |
What is the type of mechanism taking place during acylation? | Nucleophillic addition–elimination |
What is the condition for any acylation reaction. Explain why | anhydrous otherwise the acyl chloride reacts with water to form the carboxylic acid and HCl |
Why are acid anhydrides better to use than acyl chlorides for acylation? (5 reasons) | 1) anhydrides are cheaper to produce 2) anhydrides products are less corrosive 3) anhydrides reacts less readily with water 4) safer bi–product = acyl chlorides produce HCl which is a toxic gas 5) acyl chlorides reacts vigorously with water |
CHALLENGE: What is the one reason acyl chloride is better to use than acid anhydride for acylation? | Its products are easier to separate because HCl is a gas, where as acid anhydrides always product carboxylic acids which are more difficult to separate |