Halogenoalkanes Flashcards
What is a halogenoalkane?
when we have at leats one hydrogen in an alkane, replaced with a halogen.
What determines wether a halogenoalkane is primary, secondary, or tertiary?
depends on the number of alkyl groups that are bonded to the halogen containing carbon.
do halogenoalkanes have polar bonds?
yes, carbon and halogen bond.
describe the melting point of haloalkanes as size increases.
asnthe length of the chain increases, the number of electrons also increases, thus stronger wan der waals forces, which require more energy to break, and thus higher melting point.
describe what happens to the solubility of haloalkanes as we increase chain size.
As we increase chain size, number of carbon - carbon bonds, and number of carbon - hydrogen bonds, increases. This means that there is a larger non - polar region when compared to polar. This means that solubility decreases as we increase chain size.
what are the intermolecular forces that halogeno alkanes experience?
dipole - dipole forces, and van der waals forces.
what is a nucleophile?
a substance which donates an electron pair, to form a covalent bond.
what is the general formula of a haloalkane?
CnH2n+1X
which compounds can haloalkanes perform nucleophilic substitution with?
OH-, Cyanide, and NH3
state the conidtions, product(s) and reagents for when haloalkanes react with hydroxides.
aqueous ( dissolved in water)
potasium hydroxide (KOH).
Heat the mixture.
product: An alcohol.
state the conidtions, product(s) and reagents for when haloalkanes react with cyanide.
Potassium cyanide, which is dissolved in liquid ethanol.
Heat
product: A nitride.
state the conidtions, product(s) and reagents for when haloalkanes react with ammonia.
Ammonia that is dissolved in ethanol.
heat mixture.
High pressure.
ammonia in excess.
product:
Explain why it is necessary to have potassium cyanide dissolved in ethanol?
because if we dissolve it in water, we could end up producing an alcohol with the OH- from the water.
explain why we need a high pressure, excess ammonia, and ammonia dissolved in ethanol when reacting ammonia with a haloalkane.
high pressure: So that the ammonia remains dissolved in the ethanol, and so it doesnt evaporate out of the mixture.
Dissolved in ethanol: So that the NH3 doesnt recat with water, and forms OH-, which can give us an alcohol.
Excess NH3: So that we increase our chances of ammonia reacting with the halogenoalkane, rather than the amine group at the product.
state and explain the rate of reactions in haloalkanes as we go down group 7.
As we move down the halogens, bond enthalpy decreases, which means that less energy required to break the bond, thus a faster rate of reaction.
