6.3 Flashcards
what is R used to stand for in organic chemistry
an alkyl group
classify and name this halogenoalkane
CH3-CH2-CH2F
primary halogenoalkane
1-fluoropropane
classify and name this halogenoalkane
CH3-CHBr-CH3
secondary halogenoalkane
2-bromopropane
classify and name this halogenoalkane
(CH3)2CCl-CH2-CH3
tertiary halogenoalkane
2-choloro-2-methyl-butane
why are halogenoalkanes reactive
the halogen atom has a higher electronegativity than the carbon atom so the C-R bond is polar
define nucleophile
a species that donates a lone pair of electrons to form a covalent bond with an electron deficient atom
what is a hydrolysis reaction
a reaction in which water or hydroxide ions replace an atom in a molecule with an OH group
what is formed when a halogenoalkane undergoes hydrolysis by water and what does the reaction look like
an alcohol is formed
no colour change as all reactants and products are colourless liquids
how can a practical be carried out to tell how quickly hydrolysis reactions occur in halogenoalkanes
add silver nitrate solution
use ethanol as a solvent
control temp and conc
time the appearance of a precipitate
state the trend in reactivity of halogenoalkanes and explain it
iodobutane -fastest
bromobutane
chlorobutane - slowest
because bond enthalpy of C-R bonds decreases
what is elimination
reaction in which a molecule loses atoms attached to adjacent carbon atoms forming a C=C double bond
what is nucleophilic substitution
one in which an attacking nucleophile replaces an existing atom or group in a molecule
explain the reaction RX -> RNH2 in terms of producing primary amines, nucleophiles and the conditions of the reaction
the first step of the reaction produces a salt then excess ammonia reacts in a second step to produce the amine
nucleophile - NH3 molecule
conditions - heated in sealed tube so the ammonia gas doesn’t escape
what is a primary amine
compounds containing C-NH2 group
what is the attacking nucleophile and use of this reaction:
RX -> RCN
CN- ion
useful for:
extending carbon chain
synthesizing more complex compounds
