Organic Chemistry Flashcards
_______________
- detection and study of electromagnetic radiation absorbed by an organic molecule
Absorption spectroscopy
In absorption spectroscopy, the most important regions are ___________, __________, & __________.
Infrared (IR)
Ultraviolet /visible (UV/Vis)
Radio frequency (RF)
_______________ spectroscopy
- uses radiation from middle of infrared spectrum
- Energies of photons in this region correspond to energy differences between vibrational states (modes) in covalent bonded molecules
IR
The 2 type of vibrational modes in spectroscopy
____________
____________
Bends (bond angles change)
Stretches (bond lengths change)
2 types is stretches are __________ & __________
Symmetric
Asymmetric
4 types of bends are __________, __________, __________, & __________
Rocking
Scissoring
Wagging
Twisting
An IR spectrum is plotted as percent transmittance vs frequency & instead of using reciprocal time (s^-1), the frequency is given in reciprocal wavelengths called _________________
Wave numbers
IR spectrum
4,000-1,300 cm^-1 is called the ____________________ region
1,500-500 cm^-1 is called the _______________ region
Functional group region
Fingerprint region
____________ energy absorption
- leads to a change in a molecules electron configuration
- In organic compounds with double bonds the absorption results in promotion of electrons from Bonding molecular orbitals to higher energy Anti-bonding molecular orbitals
UV/Vis energy absorption
The energy change in which electrons from Bonding molecular orbitals are promoted to higher energy Anti-bonding molecular orbitals is called ____________
π —> π* transition
Other kinds of electron transitions can occur when radiation is absorbed, if certain functional groups are present
- If a C=O Bond is present then an n —> π* transition is observed where n is a _______________ molecular orbital
Non-bonding molecular orbital
Energy absorbed during electron transitions is measured & interpreted in order to provide ____________ information about the molecule being irradiated (also degree of unsaturation & conjugation)
Structural information
__________ spectra of organic compounds
- Recorded by a radiating samples with continually increasing wavelengths of radiation (higher to lower energy)
- The energy of radiation is sufficient to promote an electron to a higher energy level then the energy is absorbed & absorption is observed as a positive peak
- Spectra displayed with wavelength in nanometers at the bottom of the graph & relative absorption (unitless) along left vertical axis
UV/Vis
________ spectroscopy
- Detection & presentation of absorbed RF radiation
- Signals are due to absorption of RF radiation by nuclei
- Only nuclei with nuclear spin are suitable for this spectroscopy (such as H & C-13)
- All nuclei are positively charged
- Those that spin create their own magnetic field which can interact with external magnetic fields
NMR spectroscopy
Proton (H) NMR signals
- usually spins of protons are randomly oriented and when exposed to a strong external magnetic field they become aligned with it called _________ or against it called _________
Parallel
Anti-parallel
When a lower energy proton in the parallel state, absorbs the right amount of energy supplied by the radio-frequency radiation then it can be promoted into the higher energy anti-parallel state and the proton is _____-_______ & is in resonance with the applied radio-frequency radiation
Spin-flipped
Energy absorbed during a spin-flip is represented as a ________ in the spectrum
Peak
______________ spectra
- plotted with relative intensity of RF absorption peaks on the vertical axis & position of peaks on the horizontal axis
- Peak positions are plotted from high frequency to low frequency (from left to right)
- Absorption peak positions are measured relative to a reference signal produced by tetramethylsilane (TMS)
H NMR
_____________ defines position of NMR signals which are measured in ppm
Chemical shift
Ratio of ____/_____ leads to a parts per million (ppm) unit system
The ________ signal is assigned 0 ppm
TMS
The number of absorption peaks seen in spectrum indicates number of magnetically (equivalent OR non-equivalent) protons in a molecule
Non-equivalent
In position of the peaks (chemical shifts), the magnetic environments of protons are __________ or __________
Shielded
Unshielded
__________ protons feel the external magnetic field less & signals found upfield (closer to the TMS peak)
__________ protons feel the external magnetic field more & signals appear downfield (farther from the TMS peak)
Shielded
De-shielded
____________ is caused by non-equivalent neighboring Hydrogens’ magnetic fields interacting & if a hydrogen has no immediate neighbors then its absorption signal is a single peak (singlet)
Splitting
________________ rule
- The number is peaks from an absorption signal equals the number of its neighboring Hydrogens + 1
n + 1 rule
_______________
- selective partitioning of substance into a phase that is easily removed
Extraction
____________ extraction
- Use of 2 immiscible liquids to selectively partition a compound into 1 of the liquids
- Neither liquid can react in irreversible way with desired compound
- Extracting liquid added to the compound solution must have a higher affinity for the solute than the solvent in which the solute is dissolved (the higher partition coefficient is better)
- A partitioned solute needs to be easy to remove
Liquid-liquid extraction
____________ funnel
- Laboratory glassware used for liquid-liquid extraction
Separatory funnel
The extraction of weak acids & weak bases are often accomplished by using _______________ extraction (both of these classes of compound can be converted to water soluble salts)
Liquid-liquid extraction
_______________
- preferential vaporization of a liquid with a high vapor pressure & then condensing the vapor back to a liquid to collect it
- used to separate 2 or more miscible liquids
- The larger the difference between the liquid boiling points then the easier the separation
Distillation
__________ distillation
- used to separate low-temperature boiling liquids that have large differences in between their boiling points
Simple distillation
_______________ distillation
- used for separation of liquids that boil above 150°C
- Pressure is lowered by a vacuum source so that liquids vapor pressures increase (can boil at lower temperatures)
- Can prevent heat induced decomposition
- Requires a boiling point difference of at least 30°C for good separation
Vacuum distillation
_______________
- can separate liquids whose boiling points are closer to each other than 30°C
- Uses a fractionating column placed between the still head & pot
Frictional distillation
_______________
- separation techniques involving use of a stationary phase & mobile phase
Chromatography
_______________
- stationary phase is a thin layer of medium coated onto glass, plastic, or metal plate
- common media are silica gel, alumina (highly polar)
Thin layer chromatography
_______________
- sensitive procedure that uses a gas chromatogram & the stationary phase is a viscous silicone oil that coats the inside of a long thin glass column housed inside the instrument
- mobile phase —> gas He or N2
Gas liquid chromatography
_______________
- automated packed column chromatography that uses prepacked media columns with high separation ability for nonvolatile compounds (those with high boiling points)
- Mobile phase is a solvent system
High-performance liquid chromatography
_______________ methods
- used to separate mixtures of enantiomers
- When a mixture of enantiomers is passed through a column packed with a traditional stationary phase then the enantiomers travel at the same rate & there is no separation
- if chiral packing is used then stereoisomers move at different rates & are separated
Chromatographic methods
_______________ methods
- large molecules such as enzymes may have a preference for only one optical isomer & will use only that is in reactions at catalyzes
- the other isomer is unreacted & unchanged which results in different compounds with different properties that can be separated by traditional methods
- Used for separation of enantiomers
Enzymatic methods
_______________
- a hydrocarbon compound that is referred to as a saturated hydrocarbons because they contain the max number of Hydrogen atoms possible for their molecular structures
Alkane
Naming of Alkanes can be divided into 2 categories of compounds : __________ structures & __________ structures
Normal structures & cyclic structures
Melting & boiling points of normal alkanes show a regular (increase or decrease) as the number of carbons in their chains increases
Increases
All alkanes are (hydrophobic or hydrophilic) with relatively low densities & are flammable
Hydrophobic
True or false
Alkane combustion reactions are of commercial importance
True
_______________
- a hydrocarbon compound that is referred to as unsaturated because it contains a C=C double bond (so structure does not have max number of Hydrogens)
Alkene
True or False
The chain from which the alkene’s name is derived must be the longest in the molecule that contains the double bond
True
Alkene’s may have more than 1 double bonds & if so then a prefix must be added: diene means _____ double bonds
triene means _____ double bonds
2
3
True or false
If stereochemistry around a double bond is shown then it must be specified in the name (cis/trans or E/Z)
True
Alkenes are similar to Alkanes except they are slightly more (polar or nonpolar) due to the π portion of double bonds
Polar
Trans- alkenes are usually less polar than cis- alkenes due to __________
symmetry
Alkenes can be prepared by __________ reactions such as dehydration of alcohols & dehydrohalogenation of alkyl halides
elimination
2 common mechanisms for alkene forming elimination reactions are ____________ elimination & ___________ elimination
Monomolecular elimination (E1)
Bimolecular elimination (E2)
____________ elimination
- 1st order kinetics
- 2 steps:
1. rate determining step where formation of intermediate carbocation from loss of H2O molecule or halogen ion
2. fast step where loss of a proton adjacent to carbocation produces an alkene
Monomolecular elimination (E1)
_______________ elimination (E2)
- 2nd order kinetics
- 1 step
1. A proton is abstracted from a carbon next to a carbon with a leaving group then as the proton is abstracted the remaining electron pair moves between adjacent carbons thus the leaving group depart with a pair of electrons producing an alkene
Bimolecular (E2)
_______________
- oxygen atoms are added to double bond carbon atoms (sp2 hybridized)
- double bond may be completely cleaved
Alkene oxidation
_______________
- a hydrocarbon compound that contains a carbon-carbon triple bond functional group & also referred to as unsaturated
Alkyne
Principal chain from which alkyne’s name is derived must be the longest in the molecule that contains the triple bond & multiple triple bonds are indicated by using _______________
Greek prefixes
Because carbons in the triple bonds are sp hybridized then these groups (do or do not) exhibit stereochemical isomerism
Do not
Alkynes are similar to Alkanes and Alkenes except they are slightly more (polar or nonpolar) due to their triple bonds
Polar
- triple bonds are even more polarizable
Synthesis of alkyne functional groups is limited to a few _____________ reactions
Elimination
_______________ compounds
- contains the arene functional group
- 6-membered carbon ring with 3 alternating C=C double bonds
- many IUPAC accepted common names for monosubstituted aromatic compounds
Aromatic compounds
2 types of arene-type functional groups :
__________ aromatic compounds
__________ aromatic compounds
Heterocyclic aromatic compounds
Polycyclic aromatic compounds
__________ aromatic compounds
- 1 or more carbon atoms are replaced with heteroatoms (e.g., N)
Heterocyclic
__________ aromatic compounds
- 2 or more arene rings fused together
Polycyclic aromatic compounds
_______________
- contains hydroxyl group bonded to sp3-hybridized carbon atom
Alcohol
Alcohol nomenclature :
replace the -e suffix of an alkane with the suffix ________
-ol
(methane becomes methanol)
The longest carbon chain is considered the __________ chain
Principal chain
For complex alcohols you identify the longest carbon chain containing the carbon with the hydroxyl group & then its position is given the lowest possible number & the root name is derived from the __________ chain
Principal chain
The conversion of alkenes to alcohols uses _______________ reactions
alkene addition reactions
_______________
- a type of reaction that involves a lone pair
of electrons on a nucleophile attacking an electron deficient electrophilic center & the nucleophile bonds to the electrophilic center, resulting in the expulsion of a leaving group
- can be used for alcohol synthesis
Bimolecular nucleophilic substitution
_______________
- a type of reaction that involves replacing a functional group or atom with another negatively charged atom or group & the reaction proceeds through a two-stage mechanism, with heterolysis preceding the reaction with the nucleophile
Unimolecular nucleophilic substitution
Unimolecular nucleophilic substitution also produces an alcohol but often low yield & if a branched alkyl halide is reacted with a hydroxide base in a polar solvent then the products are primarily __________
Alkenes
Alcohol reactions are varied but the most important are __________ reactions
Oxidation reactions
Alcohol substitution reaction rates are improved by transforming __________ to mesylate or tosylate
hydroxyl
Aromatic alcohols are called ________ and have a hydroxyl group attached to arene ring
Phenols
The nomenclature of phenols are named in the same way as substituted benzene compounds but the root name is always __________
phenol
__________ is readily oxidized to benzoquinone & is important because benzoquinone is easily reduced to hydroquinone (critical for cellular respiration)
Phenol
Aldehydes & Ketones contain the _________ functional group which has a C=O double bond
Carbonyl
Aldehyde nomenclature replaces the -e suffix of alkane with the suffix _______
-al
(methane becomes methanal)
When the aldehyde group is a substituent then the prefix ________ is used
formyl-
Ketone nomenclature replaces the -e suffix of the alkane with ________
-one
(propane becomes propanone)
When the Ketone group is a substituent then the prefix ______ is used
oxo-
The polarized ________ group causes aldehydes & ketones to have an elevated boiling point due to dipole-dipole intermolecular attractive forces
carbonyl
True or False
The partially negatively charged Oxygen in the carbonyl acts as a hydrogen acceptor with molecules such as water & alcohols and the partially positively charged carbon in the carbonyl acts as an electrophile & makes hydrogens on carbons directly adjacent to it
True
Oxidation of primary alcohols –> gives __________
aldehydes
Oxidation of secondary alcohols –> gives __________
ketones
Oxidation cleavage of alkenes with a vinylic hydrogen –> gives __________
aldehydes
Oxidation cleavage of alkenes with no vinylic hydrogens –> gives __________
ketones
Hydroboration/oxidation of terminal alkynes –> gives __________
aldehydes
Hydroboration/oxidation of internal alkynes –> gives __________
ketones
Partial reduction of esters–> gives __________
aldehydes
____________ reaction for aldehydes & ketones
- attack of partially positive carbon (electrophile) in carbonyl group by neutral & negatively charged nucleophiles
Nucleophilic addition reaction
____________
- functional group contains hydroxyl group bonded to carbonyl carbon
Carboxylic acid
Carboxylic acid nomenclature replaces the -e suffix of alkane with __________
-oic acid
True of False
Carboxyl group is terminal & designated number 1 in principal chain of molecule
True
Oxidation of alcohols –> gives ________
Carboxylic acids
Oxidation of aldehydes –> gives ________
Carboxylic acids
Oxidative cleavage of alkenes –> gives __________
Carboxylic acids
Oxidative cleavage of alkynes –> gives __________
Carboxylic acids
Reduction reaction of a carboxylic acid produces a _______________
primary alcohol
The _______________ is a substitution reaction in which replaces a C-H bond on the alpha-carbon of a carboxylic acid with a C-Br bond (alpha-bromination)
Hell-Volhard-Zelinsky
Decarboxylation of a carboxylic acid is a process that removes carbon dioxide from carboxylic acids to produce ____________ (which has 1 less carbon atom than the original carboxylic acid)
Alkanes
(ethanoic acid to ethane)
Esterification reaction of a carboxylic acid produces an _________ & _______
Ester & Water
Esterification is a type of condensation reaction that occurs when a carboxylic acid reacts with an alcohol & is also known as the _______________ (during the reaction the oxygen atom becomes connected to a carbon on both sides forming an ester so carboxylic acid loses an OH & the alcohol loses a H which combine to form water)
Fischer esterification
The carboxylic acid derivative _____________ is a functional group that contains a chlorine atom bonded to a carbonyl carbon
Acid chloride
Carboxylic acid derivative Acid Chloride nomenclature changes the suffix ‘-ic acid’ to ___________
-yl chloride
Carboxylic acid derivative ____________ is a functional group that contains an Oxygen atom bonded to 2 carbonyl carbon atoms
Anhydrides
2 forms of Anhydrides are __________ & __________
Symmetrical & Mixed
Carboxylic acid derivative Anhydride nomenclature for symmetrical are named by replacing the suffix ‘acid’ with __________ & Mixed are named by __________ the names of both acids and replacing the suffix ‘acid’ with __________
anhydride
alphabetizing & anhydride
Carboxylic acid derivative __________ is a functional group that has an O bonded to carbonyl C atom & is sp3-hybridized C
Ester
Carboxylic acid derivative Ester nomenclature named as though ester derived from dehydration product of an alcohol reacting with carboxylic acid & part contributed from alcohol comes first in name and is usually an alkyl group & part contributed from carboxylic acid appears second in name and is an acyl group
- you change the suffix ‘-ic acid’ to a suffix _________
-ate
Carboxylic acid derivative __________ is a functional group that contains a nitrogen atom bonded to a carbonyl carbon atom (hydrogen atoms or other groups may be bonded to nitrogen)
Amide
Carboxylic acid derivative Amide nomenclature has the primary amides (no R groups) replace the suffix ‘-ic acid’ of carboxylic acid contributing the acyl group with the suffix _______
amide
With secondary & tertiary amides , the alkyl groups attached to the nitrogen atom must be named and If different groups are attached, then they are alphabetized & given a prefix ________
N-
The ____________ rearrangement transforms primary amides into primary amines
Hofmann
