2. Chemical Reactivity Flashcards
What is aniline?
Aniline is an organic compound consisting of a phenol group attached to an amino group
What is an aromatic ring?
A cyclic, planar molecule with a ring of resonance bonds that exhibits more stability than other geometric or connective arrangements with the same set of atoms
What is an aryl group?
A functional group derived from a simple aromatic ting compound where one hydrogen atom is removed from the ring
What is benzene?
An organic chemical compound the chemical formula C6H6. Because of the cyclic continuous pi bond between the carbon atoms, benzene is classed as an aromatic hydrocarbon
What is a carbocation?
An ion with a positively charged carbon atom
What is a covalent bond?
A chemical bond that involves the sharing of electron pairs between atoms
What are electrophiles?
A positive or neutral species having vacant orbitals that are attracted to an electron rich centre
What is Huckel’s Rule?
A compound with a planar ring system and a delocalized π-system containing (4n + 2) π-electrons, where n is an integer. Include neutral molecules, anions and cations and is aromatic
What is hybridisation?
When atomic orbitals combine to form a new atomic orbital
What is Markovnikov’s Rule?
In additions of HX to alkenes, H adds to the carbon with the greater number of hydrogens
What are nucleophiles?
A chemical species that donates an electron pair to an electrophile to form a chemical bond in relation to a reaction
What is nucleophilic substitution?
Any reaction in which one nucleophile is substituted for another
What is the ortho position?
When the functional group is on the carbon adjacent to another carbon with a functional group
What is a phenol?
A class of chemical compounds consisting of a -OH group bonded directly to an aromatic hydrocarbon group
What is regioselective?
One direction of bond-forming or bond-breaking occurs in preference to all other directions
What is resonance theory?
Theoryby which the actual normal state of a molecule is represented not by a single valence-bond structure but by a combination of several alternative distinct structures.
What does stereoselective mean?
Reactions in which one stereoisomer is formed or destroyed in preference to all others that might be formed or destroyed
What does the reaction mechanism describe?
The formation and breakage of bonds
What makes a carbocation primary, secondary or tertiary?
Depends on the number of carbons bonded to the carbon bearing the positive charge
Are carbocations Lewis acids or Lewis bases?
Lewis acids - they accept electron pairs
What types of carbocations are very stable?
secondary and tertiary
What types of carbocations are never observed?
Methyl and primary
True or False: Benzene is a planar molecule
True
What special characteristic associated with planar ring systems allows for aromacity?
Delocalised p-orbital system
What are the criteria for Huckel’s rule?
A ring must:
- Have one 2p orbital on each of its atoms
- Be planar, or almost planar, so that there is overlap between all 2p orbitals
- Have 2, 6, 10, 14, 18 and so on π electrons in the cyclic arrangement of 2p orbitals
Why is phenol more acidic than aliphatic alcohols?
Because the phenoxide ion is delocalised over the whole aromatic ring so it is very easy to remove the H ion
How do you name an amine?
Replace the suffix -e of the parent alkane with -amine
Are amines acidic or basic?
Basic
All acceptable electron redistrobutions (bond break/make) must:
- Have the same number of valence electrons
- Obey the rules of covalent bonding
- Differ only in distribution of valence electrons
- Have the same number of paired and unpaired electrons
- Have a charge balance following redistribution
What determines whether an alcohol is primary, secondary or tertiary?
The number of carbons attached to the carbon attached to the -OH group.
1 carbon = primary
2 carbons = secondary
3 carbons = tertiary
How is an alcohol converted into an alkyl halide?
Substitution of halogen for -OH
What are the most common reagents for the conversions of alcohol to alkyl halide?
The halogen acids (i.e. HCl, HF etc.) and Thionyl chloride (SOCl2)
Which type of alcohol (primary, secondary, tertiary) is very reactive with the halogen acids?
Tertiary
What do primary alcohols oxidise to?
Aldehydes or carboxylic acids
What do secondary alcohols oxidise to?
Ketones
What do tertiary alcohols oxidise to?
They don’t, they are resistant to oxidation
Why is benzene more stable than the triene model suggests?
The resonance energy makes benzene stronger than expected
For a phenol, which positions on the molecule are negatively charged?
The -OH group pushes electron density onto the ortho- and para- positions
Why are aromatic amines weaker bases than aliphatic ones?
The resonance interactions spreads the electron density therefore it is less able to pull a H ion away from another molecule
what is the formula for chromic acid
H2CrO4
