alcohols and haloalkanes Flashcards
what is name for alcohols with 1,2,3 OH groups
1= ol
2=diol
3=triol
why are alcohols soluable in water and have low volatility (higher BP)
due to difference in electronegativity between O and H causes the molecule to become polar and creates H bonding
become less soluble as number of C’s increase
what’s the difference between a primary, secondary and tertiary alcohol
primary= OH attached to a C atom that’s only attached to one other C (2 H atoms)
secondary= OH attached to a C with 2 other C attached to it
tertiary= OH attached to a C with 3 other C attached to it
give equation for combustion of alcohols ( ethanol)
C2H5+3O2=2CO2+3H2O
exothermic
how do you oxidise an alcohol, what forms
from primary and secondary alcohol
primary alcohol heated with acidified potassium dichromate, aldehyde is formed, distill off aldehyde to prevent further oxidation into carboxylic acid or strongly heated under reflux to form carboxylic acid
secondary alcohol refluxed to form ketone
how do alcohols undergo dehydration reactions, what does it form
heating alcohol under reflux in presence of an acid catalyst (eg H2SO4)
remove OH and H to form alkene and water
how can alcohol groups be substituted
with halide ions when heated under reflux with presence if acid and a sodium halide
what is a nucleophile
an atom with negative charge or with delta- charge;they have a lone pair on an electronegative atom that can be used to form a covalent bond
an electron pair donor
what type of reactions do haloalkanes undergo
nucleophilic substitutions
how can haloalkanes get substituted
when reacting with NaOH or KOH, OH acts as a nucleophile
how do you measure the rate of hydrolysis
can be measured by carrying out reaction in presence of silver nitrate and ethanol
chloroalkanes form white precipitate slowly
bromoalkenes form cream precipitate faster then chloroalkanes
iodoalkanes form yellow precipitate rapidly
why are C-F bonds the most unreactive haloalkane bond despite being the most polar and readily attacked by a nucleophile
bond enthalpy more important determinant of reactivity
C-F is strongest bond so is most unreactive
C-I is weakest bond, so most reactive
why are CFCs (chlorofluorocarbons) bad for the environment
destroying ozone layer
UV radiation causes C-Cl bond to break forming Cl radical. The C-Cl bond breaks as has lower enthalpy than C-F. causes breakdown of ozone (O3)
what is the initiation, propagation and termination reaction of CFCs with ozone
initiation:
CF2Cl2–> Cl⦁ + CF2Cl⦁
propagation:
Cl⦁ + O3–> ⦁ClO + O2
⦁ClO + O3–> 2O2 + ⦁Cl
⦁ClO + O–> O2 + Cl⦁
termination:
O3 + O–> 2O2
