9015158
Description
Flashcards by Kayla Price, updated more than 1 year ago
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Created by Kayla Price
over 7 years ago
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| Question | Answer |
| Define enthalpy change of hydrogenation | When two atoms of hydrogen add across a double bond of one mole of an alkene |
| What is the value for the enthalpy change of hydrogenation of cyclohexane? | -120kj/mol |
| What is the expected value for enthalpy of hydrogenation of the kekule structure for benzene? | 3 x -120 = -360kj/mol |
| What is the value for the experimental enthalpy of hydrogenation for benzene? | -208kj/mol |
| Explain the difference in the theoretical and experimental values for enthalpy of hydrogenation of benzene | The experimental value is less exothermic than the theoretical, showing that more energy is put in to break the bonds. This suggests that benzene is more stable than the kekule structure would be. This is thought to be due to a delocalised ring of electrons. |
| Why doesn't benzene undergo addition reactions easily? | The delocalised pi-bonds in benzene spread out the negative charge and make the ring very stable, so benzene is reluctant to break the ring. Benzene also has less attraction to electrophiles as the negative charge is reduced due to the ring. |
| Give the equation and observations for when benzene completely combusts | 2C6H6 + 15O2 --> 12CO2 + 6H2O Smoky flame - because of low carbon:hydrogen ratio |
| What are aromatic compounds? | Compounds containing a benzene ring |
| What reactions does benzene undergo? | electrophilic substitution |
| How does a halogen carrier work? | It makes compounds stronger electrophiles by accepting a lone pair of electrons from a halogen atoms on an electrophile, which polarises the molecule and makes it more electrophilic. |
| Write down the mechanism for the reaction between propanoyl chloride and benzene (including formation of electrophile). What is this reaction called? | Acylation (substitution by an acyl group) |
| How would you form nitrobenzene from benzene? | Warm with conc. nitric acid and conc. sulfuric acid. |
| What is the catalyst used in a nitration reaction? | Sulfuric acid - it reacts with nitric acid to form the electrophile (nitronium ion NO2^+) |
| At what temperature does a mononitration reaction take place? | Below 55 degrees |
| Why is phenol more reactive than benzene? | One of the lone pairs of electrons in a p-orbital of the oxygen atom overlaps with the delocalised pi-bonds in the benzene ring, which causes them to partially delocalise into the ring. This increases the electron density of the ring, making it more likely to be attacked by an electrophile. |
| What is the organic product of the reaction between phenol and bromine water? Give the observations | 2,4,6-tribromophenol Precipitate forms, smells of antiseptic |
| Describe how you would synthesise aspirin from salicyclic acid | Add some ethanoic anhydride and a few drops of phosphoric acid to salicyclic acid. Warm to 50 degrees and leave for 15 minutes. Then add cold water and cool on ice to allow aspirn crystals to form. Filter and recrystallise the crystals. |
| What is an amine? | An organic compound with the functional group NR2, where R is an alkyl group or a hydrogen |
| Name this compound | Dimethylamine |
| Name this compound | Phenylamine |
| Name this compound | Methylamine |
| Name this compound | Tetramethylamine ion |
| Name this compound | Trimethylamine |
| What are aliphatic compounds? | compounds without benzene ring structures |
| Give the mechanism for the formation of ethylamine from 1-chloroethane | |
| Why is a mixture of primary, secondary, tertiary amines and quanternary ammonium salts formed when a primary halogenoalkane is reacted with ammonia? | The nitrogen atom in the amine has a lone pair and so it undergos nucleophilic substitution reactions with other halogenoalkanes in the mixture. |
| What are the two ways you can form a primary amine from a nitrile? | Add lithium aluminium tetrahydride in dry ether, then some dilute acid or Use hydrogen gas at high temperature and pressure with a metal catalyst (catalytic hydrogenation) |
| How would you form an aromatic amine? | Heat with an aromatic nitro compound (eg. nitrobenzene), tin and concentrated hydrochloric acid under reflux. Then add sodium hydroxide. |
| Give the equation for the reduction of a nitrobenzene to form phenylamine | |
| How are primary aliphatic amines stronger bases than ammonia? | Alkyl groups shift electron density onto the nitrogen atom, making the lone pair more available to accept protons |
| Why are aromatic amines weak bases? | The lone pair of electrons on the nitrogen overlap with the delocalised ring of electrons in the benzene, so electron density on the nitogen decreases. This makes the lone pair less available to accept protons |
| Give the equation for the neutralisation of butylamine. Name the product | Butylammonium chloride |
| How does solubility of amines change as you increase the carbon chain length? | Solubility decreases as greater london forces form between amine molecules, which means more energy is required to overcome them to form new bonds with water |
| Give the colour change when a small amount of butylamine is added to copper sulfate solution followed by an excess and explain why this change occurs. | Blue -> Pale blue precipitate -> deep blue When a small amount is added, the amine acts as a base and takes two H+ ions from the aqueous copper(II) complex, which forms insoluble copper hydroxide. When an excess is added the precipitate dissolves to form a deep blue solution as butylamine molecules begin to replace the ligands, forming soluble complex ions. |
| Give the mechanism for the reaction between ethanoyl chloride and butylamine. Name the product | |
| What further reaction occurs after ethanoyl chloride and butylamine react? | The HCl produced goes on to react with butylamine to form butylammonium chloride |
| What are the observations for when ethanoyl chloride is added to conc. aqueous solution of an amine? | Violent reaction, produces solid white product |
| What is the functional group for an amide? | -CONH2 |
| Why do amides behave differently from amines? | The carbonyl group on the amide pulls electron density towards it and away from the NH2 group |
| What is an N-substituted amide? | When one of the H's on the N is substituted for an alkyl group |
| Name this compound | Propanamide |
| Name this compound | N-ethylpropanamide |
| How are primary amides formed? | Adding concentrated ammonia to ethanoyl chloride at room temperature |
| How are N-substituted amides formed? | Adding a primary amine to ethanoyl chloride at room temperature |
| What is condensation polymerisation? | The joining of two different types of monomers with at least two functional groups, each functional group reacts with a group on another monomer to form a link |
| What monomers react together to form polyamides? | Dicarboxylic acids and diamines |
| Give the equation for the formation polyamides | |
| Give the equation to show how amino acid monomers form protein chains | |
| How are amino acids hydrolysed? | By adding hot aqueous 6M HCl, then reflux for 24 hours. This forms the ammonium salts of the amino acids, which are neutralised using a base. |
| How are polyesters formed? Give the equation and label the ester link | Carboxyl groups react with hydroxyl groups to form ester links |
| Give the general structure of an amino acid | |
| What is a zwitterion? | An overall neutral molecule that has both a positive and a negative charge on different parts of the molecule |
| Under what conditions does an amino acid exist as a zwitterion? | At the pH where the overall charge on the amino acid is zero (at its isoelectric point) |
| How does the structure of amino acids change as pH increases? | In acidic conditions, the NH2 group is protonated, giving the amino acid acidic properties. At the isoelectric point, both the carboxyl group and the amino group are ionised, forming a zwitterion. In basic conditions, the carboxyl group is deprotonted, giving the amino acid basic properties. |
| What type of amino acid is naturally occurring? | 2-amino acids, amino group positioned on carbon-2 |
| What amino acid is not chiral? | Glycine |
| How are grignard reagents formed? | By refluxing a halogenoalkane with magnesium in dry ether |
| Give the equation and conditions for the reaction between grignard reagent and carbon dioxide | A new C-C forms between the C in the carbon dioxide and the C-Mg carbon from the grignard. One of the C=O bonds in the CO2 is broken to form a C-O-, which is then protonated by the acid to form a C-OH. |
| How are alcohols formed from grignard reagents? | An aldehyde or ketone is added - A new C-C bond forms between the C-Mg carbon and the C=O carbon, this breaks the C=O bond and when acid is added forms a C-OH group. |
| What reactions do alkanes tend to undergo? | Radical substitution |
| What reactions do alkenes tend to undergo? | Electrophilic addition |
| What reactions do aromatic compounds tend to undergo? | Electrophilic substitution |
| What reactions do alcohols tend to undergo? | Nucleophilic substitution, dehydration/elimination, esterfication, nucleophilic substitution |
| What reactions do halogenoalkanes tend to undergo? | Nucleophilic substitution, elimination |
| What reactions do amines tend to undergo? | Neutralisation, nucleophilic substitution |
| What reactions do nitriles tend to undergo? | Reduction, hydrolysis |
| What reactions do aldehydes tend to undergo? | Nucleophilic addition, reduction, oxidation |
| What reactions do ketones tend to undergo? | Nucleophilic addition, reduction |
| What reactions do carboxylic acids tend to undergo? | Neutralisation, esterfication, reduction |
| What reactions do esters tend to undergo? | Hydrolysis |
| What reactions do acyl chlorides tend to undergo? | Nucleophilic addition-elimination, condensation, friedel-crafts acylation |
| How would you form a halogenoalkane from and alkane? | X2 and UV light |
| How would you form a halogenoalkane from an alkene? | HX, room temperature |
| How would you form an alkene from a halogenoalkane? | Add KOH and ethanol and heat under reflux |
| How would you form an alkane from an alkene? | Add H2, nickel catalyst, 150degrees |
| How would you form a dihalogenoalkane from an alkene? | Add X2 at room temperature |
| How would you form a diol from an alkene? | Acidified KMnO4 at room temperature |
| How would you form an alcohol from an alkene? | Steam, H3PO4 catalyst, 300degrees, 60-70 atm |
| How would you form an alkene from an alcohol? | Conc. H3PO4, 170degrees |
| How would you form an ester from an alcohol? | Add carboxylic acid, acid catalyst, heat or Add an acyl chloride |
| How would you form an alcohol from an ester? | Add dilute acid or alkali and reflux |
| How would you form a bromoalkane from an alcohol? | Add KBr, 50% conc. H2SO4 at room temperature |
| How would you form a chloroalkane from an alcohol? | Add PCl5 or HCl at room temperature |
| How would you form an alcohol from a halogenoalkane? | Add warm aqueous KOH and reflux or Add Mg, dry ether, then dilute acid |
| How would you form a primary amine from a halogenoalkane? | Add excess ethanolic ammonia and heat |
| How would you form a nitrile from a halogenoalkane? | Add KCN and ethanol and reflux |
| How would you form a carboxylic acid from a halogenoalkane? | Add Mg, dry ether, CO2, then dilute acid |
| How would you form an iodoalkane from an alcohol? | Add red phosphorus, I2 (to make PI3), then reflux |
| How would you make an aldehyde or ketone from an alcohol? | Add K2Cr2O7 and sulfuric acid, distil primary for aldehydes and reflux secondary for ketones |
| How would you form an alcohol from an aldehyde/ketone? | Add LiAlH4 |
| How would you form a hydroxynitrile from an aldehyde/ketone? | Add KCN and H+ or HCN, then ethanol and reflux |
| How would you form a carboxylic acid from an alcohol? | Add acidified potassium dichromate and reflux |
| How would you form a carboxylic acid from a ketone? | Add I2 and NaOH |
| How would you form an alcohol from a carboxylic acid? | Add LiAlH4 |
| How would you form a primary amine from a nitrile? | Add LiAlH4, then dilute acid or H2, nickel or platinum catalyst and high pressure and temp |
| How would you form a carboxylic acid from a nitrile? | Add dilute HCl and reflux |
| How would you form an ester from a carboxylic acid? | Add alcohol, acid catalyst and heat |
| How would you form a carboxylic acid from an ester? | Add dilute acid or alkali and reflux |
| How would you form an ester from an acyl chloride? | Add alcohol at room temperature |
| How would you form a carboxylic acid from an acyl chloride? | Add cold water |
| How would you form an acyl chloride from a carboxylic acid? | Add PCl5 at room temperature |
| How would you form a primary amide from an acyl chloride? | Add NH3 at room temperature |
| How would you form an N-substituted amide from an acyl chloride? | Add a primary amine at room temperature |
| How would you form nitrobenzene from benzene? | Add conc. nitric acid and conc. sulfuric acid below 55degrees |
| How would you form phenylamine from nitrobenzene? | Add tin, conc. HCl, reflux then add NaOH |
| How would you form alkyl benzene from benzene? | Add a halogenoalkane, AlCl3 catalyst, reflux |
| How would you form a halobenzene from benzene? | Add X2, halogen carrier at room temp |
| How would you form phenylketone from benzene? | Add an acyl chloride, AlCl3 catalyst and reflux |
| How would you form a bromophenol from a phenol? | Add bromine water |
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