LQ3 Flashcards
The maximum number of stereoisomers is 2n
stereogenic centers
These are two types of stereoisomers
Enantiomers and diastereomers
A type of stereoisomers that are mirror images
Enantiomers
A type of stereoisomers that are not mirror images
Diastereomers
It is an achiral compound that contains tetrahedral stereogenic centers
Meso compound
These can be used to determine whether two compounds are identical, enantiomers, diastereomers
R,S configuration
It has exactly opposite R,S designations
Enantiomers
It has the same R,S designation for at least one stereogenic center and the opposite for at least one of the other stereogenic centers
Diastereomers
It has the same molecular formula but the atoms are bonded to different atoms
Constitutional isomers
cis and trans are always
diastereomers
It is an ordinary light consists of electromagnetic waves that oscillate in all planes perpendicular to the direction in which the light travels
plane-polarized
Passing light through a polarizer allows light in only one plane to come through resulting in
plane-polarized light
It has electric vector that oscillates in a single plane
Plane-polarized
It is an instrument that allows plane-polarized light to travel through sample tube containing an organic compound
Polarimeter
The light exits the sample tube unchanged, and the plane of the polarized light is in the same position it was before entering the sample tube
Achiral compounds
A compound that does not change the plane of polarized light is said to be
Optically inactive
With chiral compounds, the plane of the polarized light is rotated through an angle measured in degrees called
observed rotation
A compound that rotates the plane of polarized light is said to be
Optically active
If the rotation is clockwise (to the right from the noon position), the compound is called _____. The rotation is labeled d or (+)
dextrorotatory
If the rotation is counterclockwise (to the left from the noon), the compound is called _____. The rotation is labeled I or (-)
Levorotatory
How does the rotation of two enantiomers compare?
Two enantiomers rotate plane-polarized light to an equal extent but in the opposite direction
An equal amount of two enantiomers is called a ________
racemic mixture
Formula of enantiomeric excess =
% of one enantiomer - % of the other enantiomer
It is the most abundant simple carbohydrate, is the building block for starch and cellulose and a major sweet-tasting component of honey
Glucose
refers to the three dimensional structure of a molecule
Stereochemistry
It is a measurement of how much one enantiomer is present in excess of the racemic mixture
Enantiomeric excess
It is the heart of organic chemistry
Reactions
It is a reaction in which an atom or a group of atoms is replaced by another atom or group of atoms
Substitution
It is a reaction in which elements of starting material are “lost” and a pi bond is formed
Elimination
It is a reaction in which elements are added to the starting material
Addition
These are exactly opposite.
Addition and elimination
It is a detailed description of how bonds are broken and formed as starting material is converted into product
Reaction mechanism
A type of reaction is called a concerted reaction. No matter how many bonds are broken or formed, a starting material is converted directly to a product
One-step
A reaction involves more than one step
Stepwise
A starting material is first converted to an unstable intermediate which then goes on to form the product
reactive intermediate
Regardless of how many steps are there are in a reaction there are only ________ to break (cleave) a bond
two ways
the electrons in the bond can be divided ____________ between two atoms of the bond
equally or unequally
breaking a bond by equally diving the electrons between two atoms in the bond is called
homolysis or homolytic cleavage
It generates two uncharged species with unpaired electrons
Homolysis
A reactive intermediate with a single unpaired electron is called
radical
These are highly unstable because they contain an atom that does not have an octet of electrons
radicals
Heterolysis of a C-Z bond generates a
carbocation or a carbanion
It is an unstable intermediate containing a carbon surrounded by only six electrons
Carbocation
It is unstable intermediate having a negative charge on carbon, which is not a very electronegative atom
carbanion
carbocations are ______ because they contain an electron-deficient carbon
electrophiles
carboanions are________ because they contain carbon with a lone pair
nucleophiles
As a chemical reaction proceeds from reactants to products, it passes through an unstable energy maximum called
Transition state
The energy difference betweeen the transition state and the starting material is called the
energy of activation, Ea
The larger the Ea the greater the amount of energy that is needed to break bond
and the slower the reaction rate
the structure of the _______ is somewhere between the structures of the starting material and product
transition state
Transition states are drawn in brackets, with a superscript
double dagger
The use of half-headed curved arrow is sometimes called
fishhook
Giving two electrons to Z and none to carbon generates a positively charged carbon intermediate called
carbocation
Giving two electrons to C and none to Z generates a negatively charged carbon species called
carbanion
It is the energy needed to homolytically cleave a covalent bond
Bond dissociation
The stronger the bond the ___________ its bond dissociation energy
higher
It describes the energy and equilibrium
Thermodynamics
It describes the rated or how fast reactants converted to products?
Kinetics
It is a schematic representation of the energy changes that take place as reactants are converted to products
Energy diagram
It plots the energy on the y axis versus
the progress of reaction, often labeled as the reaction
coordinate, on the x axis.
Energy diagram
The energy difference between reactants and products is
ΔH°
transition state.
The energy difference between the transition state and the starting
material is called the energy of activation, E a .
transition state
the greater the amount of energy that is needed to
break bonds, and the slower the reaction rate.
The larger the E a
It is the minimum amount of energy needed to break bonds in the reactants
energy of activation
The step with the highest-energy transition state is called
rate determining step
The higher the ______, the faster the rate
concentration
The higher the ________ the faster the rate
Temperature
ΔG°, ΔH°, and Keq ____ determine the rate of a reaction
do not
These quantities indicate the ________ of the equilibrium and the relative energy of reactants and products
direction
A ____ shows the relationship between the reaction rate and the concentration of the reactants
Rate law or rate equation
It is experimentally determined by measuring the decrease in concentrations of reactants or the appearance of products over time
Rate law
Fast reactions have _______
large rate constants
Slow reactions have _______
small rate constants
A rate equation contains concentration terms for all reactants in
One-step mechanism
A rate equation contains concentration terms for only the reactants involved in the _______ step in a multistep reaction
rate-determining
The _____ of a rate equation equals the sum of the exponents of the concentration terms in the rate equation
order
For a reaction mechanism with multiple steps, the rate law can often be used to identify the the rate-determining step (the slowest step in the mechanism).
Elementary Steps
The presence of intermediates can sometimes be inferred if the rate law includes terms that do not match the overall stoichiometry of the reaction.
Intermediates
Some reactions do not proceed at a reasonable rate unless a _________ is added
catalyst
It is a substance that speeds up the rate of a reaction
catalyst
It is recovered unchanged in a reaction, and it does not appear in the product
Catalyst
It lowers the activation energy, thus increasing the rate of the ____ reaction
Catalyzed
The energy of reactants and products is the same in both the catalyzed and uncatalyzed reactions
the position of equilibrium is unaffected
These are biochemical catalysts composed of amino acids held together in a very specific three-dimensional shape
Enzymes
An enzyme contains a region called its active site which blinds an organic reactant, called a _________
substrate
The resulting unit is called
the enzyme-substrate complex
Once bound, the organic substrate undergoes a very specific reaction at an enhanced rate
Enzymes
The products are then released
Enzymes
These are organic molecules containing a halogen atom bonded to an sp3 hybridized carbon atom
Alkyl halides
The halogen atom in halides is often denoted by the symbol
X
These are classified as primary, secondary, tertiary, depending on the number of carbons bonded to the carbon with the halogen atom
Alkyl Halides
Have a halogen atom (X) bonded to a C-C double bond
Vinyl Halides
