Organic Chemistry Flashcards Flashcards by Dack Punke

_______________
- detection and study of electromagnetic radiation absorbed by an organic molecule

Absorption spectroscopy

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In absorption spectroscopy, the most important regions are ___________, __________, & __________.

Infrared (IR)
Ultraviolet /visible (UV/Vis)
Radio frequency (RF)

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_______________ 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

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The 2 type of vibrational modes in spectroscopy
____________
____________

Bends (bond angles change)
Stretches (bond lengths change)

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2 types is stretches are __________ & __________

Symmetric
Asymmetric

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4 types of bends are __________, __________, __________, & __________

Rocking
Scissoring
Wagging
Twisting

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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

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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

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____________ 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

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The energy change in which electrons from Bonding molecular orbitals are promoted to higher energy Anti-bonding molecular orbitals is called ____________

π —> π* transition

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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

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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

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__________ 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

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________ 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

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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

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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

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Energy absorbed during a spin-flip is represented as a ________ in the spectrum

Peak

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______________ 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

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_____________ defines position of NMR signals which are measured in ppm

Chemical shift

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Ratio of ____/_____ leads to a parts per million (ppm) unit system

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The ________ signal is assigned 0 ppm

TMS

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The number of absorption peaks seen in spectrum indicates number of magnetically (equivalent OR non-equivalent) protons in a molecule

Non-equivalent

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In position of the peaks (chemical shifts), the magnetic environments of protons are __________ or __________

Shielded
Unshielded

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__________ 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

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____________ 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