Flashcards
6.1.1 Aromatic compounds
Cards in this deck (33)
- 1What is the structure and formula of Benzene?
- 2What is the empirical formula of benzene?CH
- 3What is the state of benzene at room temperature?Liquid
- 4What is the bond angle of benzene?120
- 5What are the 3 features of benzene that don’t support Kekule’s model?● Benzene is resistant to addition reactions
● Enthalpy change of hydrogenation of benzene
is more stable than predicted
● All the carbon bonds are same length - 6What technique was used to find the bond lengths of benzene?X ray diffraction
- 7What happens to the 4th electron in the p-orbital of each carbon atom in benzene?It delocalises to form rings of electron density above and below the hexagon, forming rings of delocalised electron density above/below the hexagon.
- 8How do the rings of electron density affect the stability of Benzene?Makes benzene very stable, even though it is unsaturated (aromatic stability)
- 9Draw the skeletal structure of cyclohexa-1,3,5-triene.
- 10Why does benzene have a relatively high melting point?Close packing of flat hexagonal molecules when solid
- 11Is benzene soluble in water? Explain why?No because it is non polar
- 12Dangers of benzene - why it is not used in schools?It is a carcinogen
- 13How do you name compounds containing a benzene ring?-benzene, or phenyl- ; can designate position on ring using numbers if there is more than one substituent
- 14Why is benzene attacked by electrophiles?High electron density above/below ring due to delocalised electrons
- 15Draw a general electrophilic substitution mechanism of benzene, using El+ to represent an electrophile.
- 16Nitration of benzene is what type of reaction?Electrophilic substitution reaction
- 17Which ion is used to nitrate benzene?NO2 +
- 18What is the catalyst in nitration of benzene?Sulfuric acid
- 19How is this NO + ion generated? (conditions and 2 equations)Concentrated H2SO4 and concentrated HNO3
H2SO4 + HNO3 → H2NO3 + + HSO4 -
H2NO3 + → H2O + NO2 +
Overall: H2SO4 + HNO3 → HSO4 - + NO2 + + H2O - 20How is the H2SO4 catalyst regenerated in the nitration of benzene?HSO4 - + H+ → H2SO4 (H+ from benzene
ring) - 21Draw a mechanism and write an overall equation for the nitration of benzene.
- 22What type of catalyst is used for a Friedel-Crafts reaction?A halogen carrier (e.g. AlCl3)
- 23Why does benzene not react directly with halogens?The aromatic ring is too stable
- 24What is happening when AlCl4 - is formed in terms of electrons?The lone pair of electrons on the chlorine atom is forming a coordinate bond to Al
- 25How is the AlCl3 catalyst reformed?AlCl4 - + H+ → HCl + AlCl3 (H+ from benzene)
- 26How could you use a Friedel-Crafts mechanism to add a methyl group to a benzene ring?Use a halogenoalkane and AlCl3 to create an electrophile that can attack benzene
- 27Draw the structure of phenol?
- 28What reactions can you carry out to show the weak acidity of phenol?A neutralisation reaction with NaOH occurs but absent when you react phenol with carbonates
- 29Write the equation of the reaction between phenol with bromine to 2,4,6-tribromophenol?
- 30Write the equation for the reaction between phenol with dilute nitric acid.
- 31What is the relative ease of electrophilic substitution of phenol compared to benzene and why?It is easier for electrophilic substitution to occur with phenol because oxygen lone pair of electrons from the -OH group are partially delocalised into ring therefore this increases the electron density of the ring thus electrophiles are more attracted phenol
- 32What is the directing effect of electron donating groups OH and NH2?They direct group to the 2 and 4 position of the ring in electrophilic substitution of aromatic compounds
- 33What is the directing effect of electron withdrawing group NO2?NO2 directs atoms to the 3 position of the ring in electrophilic substitution of aromatic compounds
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- A level Chemistry (Module 6 – Organic Chemistry & Analysis) Flashcards on 6.1.1 Aromatic compounds, created by Aania Bokhari on 05/03/2019.
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- Aania Bokhari
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