Key points Flashcards
Which compound is the least polar?
-pure hydrocarbons, then ethers, etc. charged compounds or with H bonds or extra electrons are polar (ie. an ether less polar than a carbocation)
Can a monosubstituted benzene ring act as an electrophile?
NO because aromatic compounds do not undergo nucleophilic aromatic substitution thus can only act as nucleophiles
When are two compounds diastereoisomers?
They have same stereochemistry on one stereocenter and opposing stereochemistry on the other. Cis/trans and E/Z compounds also display diastereoisomers
When do we use cis/trans and when E/Z notation?
Cis/trans used for rings and E/Z for alkenes
what is an acyl halide?
-C0Cl functional group (don’t confuse with alkyl halide which is a haloalkane)
How can we convert directly from nitrobenzene to (p)4-chloro-1-nitrobenzene?
We cannot directly do this; NO2 is meta directing
Define rate constant
proportionality constant (k) in rate law ie. For first order reaction rate, rate proportional to k (A)
Define first order reaction
Where the overall reaction order in the rate law is 1. The rate is directly proportional to the concentration of a reactant (rate=k(A))
define half life
the time take for the concentration of a reactant to fall to half of its initial value (give equation for 1st order R half life)
Define a heterogeneous/homogeneous catalyst
Catalysts are substances that speed up a reaction without being used up in the overall process. A heterogeneous catalyst is in a different phase to the reactants. For example Pt (solid) in the hydrogenation of alkenes (gas)
A homogeneous catalyst is in the same phase as the reactants (ie. gas catalyst in a gaseous reaction) homogeneous catalysts usually appear in rate law
Define transition state in an elementary reaction
Transition state in an elementary reaction is the point of highest energy between reactants and products (marked so# in a reaction profile-must draw a diagram to support this)
Explain the terms average and instantaneous rate
Average rate is the change in rate over a time interval (change in conc over time). However instantaneous rate is the rate at a specific point in time during the course of the reaction (give by a tangent to the curve of the conc vs time plot-must give a diagram for both)
define rate law
relationship between rate and concentration (ie.rate proportional to (A))
Define rate constant
proportionality constant in the rate law (give example)
define a third order reaction
Where the overall reaction order in the rate law is three. The rate is 3rd order in a single reactant or 2nd order in 1 and 1st order in another or 1st order in 3 reactants (and write the three possible equations)
Define activcation energy
Activation energy is the energy required by the reactants to reach the transition state (draw a diagram and label both Ea and #)
Define arrhenius equation
Arrhenius equation gives the relationship for the temperature dependence of the reaction rate constant (give the equation)
acid anhydride functional group
-COOOC-
nitrile fucntional group
NN (triple bond)
acyl vs alkyl halide
-COCl (acyl halide), -CCl (alkyl halide)
Enantiomers
mirror images of each other( have opposing stereochemistry at all stereocenters)
What happens when more than one functional group is present?
Name based on O containing functional group
ie. pent-3-en-2-one
Explain chromatography
Molecules separated based on polarity. Polar solutes are more attracted to the polar stationary phase and move slowly while non-polar are less attracted to the polar phase of the stationary phase and therefore move more rapidly (with the non-polar solvent)
Nucleophiles
Electron donors; are either -vely charged or neutral and will have either lone pairs of electrons or electrons in p bonds
Electrophiles
Electron acceptors; can be neutral (have a polar bond) or +vely charged
How do we calculate number of Hs?
(2 (C)+ 2)-(2*DBE)+1(N) -1(Halogen)
In which order do we write the atoms in the molecular formula?
1st C then H, the rest follow with alphabetical order
