Ch. 20: Organic Chemistry I: Structures Flashcards
What is the name for molecules you can smell?
odourants
How do we smell odourants?
the odourants bind with olfactory receptors in our nose and a nerve signal is sent to the brain
Define organic molecule
A molecule containing carbon combined with several other elements including hydrogen, nitrogen, oxygen, or sulphur
Define organic chemistry
The study of carbon-based compounds
name three reasons why carbon is unique
- it tends to form 4 covalent bonds
- it is able to form single, double and triple bonds
- it has a tendency to catenate (form chains)
define structural isomers
Molecules with the same molecular formula but different structures
define structural formula
A molecular formula that shows how the atoms in a molecule are connected or bonded to each other
define alkane
A hydrocarbon containing only single bonds
define alkene
A hydrocarbon containing one or more carbon-carbon double bonds
define alkyne
A hydrocarbon containing one or more carbon-carbon triple bonds
define saturated hydrocarbon
A hydrocarbon containing no double (or triple) bonds in the carbon chain
define unsaturated hydrocarbon
A hydrocarbon that includes one or more double or triple bonds
define conjugation
a sequence of alternating single and double bonds that results in delocalized pi bonding
define aromatic hydrocarbon
A class of organic molecules that contain rings with alternating single and double C-c bonds
conjugation leads to a _____ molecular structure
planar
what are polycyclic aromatic hydrocarbons (PAHs)?
hydrocarbons that have two or more rings that are connected
define functional groups
A characteristic atom or group of atoms that imparts certain chemical properties to an organic compound
define family
a group of organic compounds with the same functional group
halogens are _____ ____ than carbon, which means that the halogen-carbon bonds are ____
more electronegative
polar
all organic halides are polar molecules except when…?
individual bond dipoles cancel out
define inductive affect
the through-bond donation or withdrawal of electron density
In halides the carbon bonded to the halogen atom has a partial ____ charge and the halogen has a partial ____ charge
positive
negative
the bond dipole between carbon and the halogen atoms ____ (does or does not) affect the polarity of adjacent bonds
does
Define R groups
general representation of an alkyl group in an organic compound
what is an amine
a nitrogen that has three single bonds to hydrogen or R groups
what is the hybridization of amines?
sp3
what is the electron geometry of amines?
tetrahedral
what is the molecular geometry of amines?
trigonal pyramidal
why are amines polar?
due to the electronegativity of the nitrogen atom
define alcohol
a memember of the organic family of compounds that contain a hydroxyl functional group (-OH)
what is the general form of alcohols?
R-OH
what is the hybridization of the Oxygen in alcohols?
sp3
what affect do the lone pair electrons on the oxygen of an alcohol have on the bond angles?
the bond angles are slightly less than perfect tetrahedral
what causes the very polar bond between carbon and oxygen in an alcohol?
carbons aren’t electronegative and oxygens are very electronegative
what does the polar bond between hydrogen and oxygen in alcohols cause?
strong hydrogen bonding between alcohols
due to the ____ of alcohols they are miscible in water, but as the hydrocarbon gets bigger the alcohol becomes ___ soluble
polarity
less
a atoms polarity makes its boiling point ____ than a non polar version of itself
higher
what is the general form for ethers?
R-O-R’
what is the hybridization of the oxygen in ethers?
sp3
are ethers polar?
yes they are slightly polar however not polar enough to dissolve in water
what group do both aldehydes and ketones contain?
a carbonyl group O=C
what is the general formula of a aldehyde?
R-C-H
||
O
what is the general formula of a ketone?
R–C–R
||
O
aldehydes has one R group and one H with the exception of ____ which has…?
methanal
two H atoms
what is the hybridization of the oxygen in an carbonyl?
sp
what is the hybridization of the carbon in an carbonyl?
sp2
define aldehyde
a functional group with the formula RCHO, in which the R group may also be a hydrogen atom
define ketone
a functional group in which a carbon is double-bonded to an oxygen atom, and two R groups
define carbonyl group
a functional group consisting of a carbon atom double-bonded to an oxygen atom (C=O)
define acyl group
a functional group with the group RCO, in which the carbon atom is also bonded to a polar group
do carbonyls have resonance structures?
yes
what is the general structure of carboxylic acid?
R-C-OH
||
O
what is the difference between the carbonyl group and a acyl group?
there is a substituent group on the acyl group which is not a hydrogen or alkyl group bonded to the central carbon atom. instead it has a polar group
why are amides relatively unreactive compared to other acyl funtional groups?
the are stabilized by their resonance structures
define constitutional isomers
a molecule that has the same molecular formula, but atoms are connected in a different sequence
what is the general formula for a hydrocarbon chain?
CnH2n+2
what is the general formula for a cycloalkane?
CnH2n
compounds that have the same molecular formula bu different funtional groups are…?
constitutional isomers
define stereoisomerism
molecules in which the atoms are bonded in the same order, but have a different spatial arrangement
what are the two categories of isomerism
conformational and configurational
define conformational isomerism
a type of stereo isomerism that is the result of bond rotations
define configurational isomerism
a type of stereoisomerism in which atoms or funtional groups are connected in the same sequence, but there is a difference in the spatial locations of atoms or groups
define conformers
a conformational isomer
define rotamers
a conformational isomer
define three-dimensional formula
a representation of a molecular shape in three dimensions, showing some bonds as solid and hashed wedges
define Newman projection formula
a representation of a molecular conformation in which one looks down the C-C bond of interest
define staggered conformation
the rotational conformation around a C-C bond in which the groups are located 60° fro, each other
define eclipsed conformation
the rotational conformation about a C-C bond in which the groups are located 0° from each other
define torsional strain
the difference in potential energy of staggered and eclipsed conformations
define steric strain
a repulsive interaction between groups bonded to adjacent carbon atoms that hinders bond rotation
define antistaggered conformation
the rotational conformation about a C-C bond in which the bulky groups are located 180° from each other
define gauche-staggered conformation
the rotational conformation about a C-C bond in which bulky groups are located 60° from each other
define chair conformation
the most stable conformation of cyclohexane
define equatorial bonds
In the chair conformation of cyclohexane, the bonds that are pointed outward, to the sides of the ring
define axial bonds
In the chair conformation of cyclohexane, the bonds that are pointed vertically above and below the ring
define enantiomers
two molecules that are non superimposable mirror images of one another
define diastereomers
configurational isomers that are not mirror images (and are nonsuperimposable)
define cis-trans isomerism
cis-isomers have the same funtional groups on the same side of a bond and trans-isomers has the same funtional groups on the opposite sides of the bond
define E,Z system
the protocol for assigning stereochemical configuration of an alkane with three or more different groups
define chirality
the type of isomerism in which moleucles are nonsuperimposable mirror images
define chirality center
a carbon atom with four different substituents in a tetrahedral arrangement
define optical activity
the ability of a chiral compound to rotate plane-polarized light
define levorotatory isomer (L-isomer)
capable of rotating the plane polarized light counter clockwise
define dextrorotatory isomer (D-isomer)
capable of rotating the plane polarized light clockwise
define racemic mixture
an equimolar mixture of two enantiomers that does not rotate the plane of polarization of light at all
define absolute configuration
the exact three-dimensional spatial arrangement of atoms at a chirality center
define R,S system
the protocol for assigning stereo-chemical configuration of achirality center
how fast to the C-C bonds rotate at room temperature?
extremely fast, to the order of the pico second
eclipsed conformers are ____ in energy than staggered conformers
higher
eclipsed conformers are higher in energy than staggered conformers and this results in a ____ ____ for the rotation of the C-C.
energy barrier
what is one explanation for torsional strain?
staggered conformers are more stable than eclipsed conformers
antistaggered conformation has ___ steric strain than Gauche-staggered conformation
less
define angle strain
???
to intercovert between two conformatinal isomers what needs to happen?
the C-C bond must rotate
to intercovert between two configurational isomers what needs to happen?
covalent bonds must break
what are the three CIP rules for assigning priority
(1) determine priority based on atomic mass
(2) if the the atoms connected to the carbons are the same then look at the next atom’s atomic mass and so on
(3) if the substituent contains a double of triple bond, treat it as though there are two (or three if its a triple bond) attached to it
