Chem219 Unit 4 Test with Questions
Solved 100% Correct | Latest Update
By using nucleophilic substitution, a vast array of different types of
compounds can be created starting from a simple alkyl halide.
What is the substrate in a nucleophilic substitution reaction? -
✔✔The molecule on which the substitution occurs
What is the leaving group in a nucleophilic substitution reaction? - ✔✔An
atom (or group of atoms) that is replaced by another when the substitution
occurs (the halogen).
What is the nucleophile in a nucleophilic substitution reaction? - ✔✔The
replacing group.
A chemical species that seeks positive charge (nucleo = nucleus/positive
charge, phile = love).
What is the solvent in a nucleophilic substitution reaction? - ✔✔The solution
in which the reagents are combined.
Generic formula for nucleophilic substitution reaction - ✔✔Nucleophile: +
Substrate - Leaving Group --> Nucleophile - Substrate + Leaving Group:
,During a nucleophilic substitution reactions what bond are broken and what
bonds are formed? - ✔✔The bond between the leaving group (halogen) and
the carbon is broken, and a new bond between the nucleophile and the carbon
is formed.
What causes the new bond to form between the nucleophile and the
substrate during a nucleophilic substitution reaction? - ✔✔The polarization
of the C-X bond.
Due to the polarization of this bond, the carbon possesses a + charge and is a
site for the positive charge-loving nucleophile to "attack".
Why are nucleophiles positive charge-seeking? - ✔✔Due to the presence
of one or more lone pairs present on an atom in the nucleophile.
What types of atoms can be nucleophiles? - ✔✔Typically, heteroatoms such as
O, N, and S act as nucleophilic atoms - leading to the formation of C-O, C-N, and C-
S bonds.
Nucleophiles can also be anions of carbon (C: -), and these nucleophiles can
form C-C bonds as well. The nucleophile is often negatively charged (anionic) but
can also be neutral.
How do negatively charged nucleophiles and neutral nucleophiles differ in
their substitution reactions with the substrate? - ✔✔A negatively charged
nucleophile is more reactive than a neutral species because it seeks positive
charge more strongly.
, In reactions where a neutral molecule acts as the nucleophile, a second molecule
is usually involved, typically to act as a base to remove a proton to help form the
final product.
Which type of substrates are unreactive in nucleophilic substitution reactions, and
why? - ✔✔- Aryl and vinyl halides
- substrates in which the halogen is attached to a carbon that is part of a multiple
bond.
These types of substrates have the halogen attached to a carbon with a
hybridization other than sp3 and prevent the nucleophile from reacting with
the substrate.
mechanism - ✔✔Mechanisms show the flow of electrons between
molecules and ions as the reagents are converted to products.
A term used by organic chemists to describe and explain how reactions happen
at the molecular level. Sometimes, mechanisms are referred to as "roadmaps" of
chemical reactions because they describe the stepwise formation of products
from the reactant molecules, just as a road map can provide street-by-street,
stepwise directions to get from place A to place B.
How are mechanisms shown? - ✔✔Curved arrow notation is used to draw
mechanisms in organic chemistry, just like when showing electron resonance.
What factors affect which type of mechanism occur for a substitution reaction? -
✔✔- The structure of the substrate: is it a methyl, primary, secondary, or
tertiary alkyl halide? (this is the most influential factor)
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