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MCAT OChem
| Term | Definition |
|---|---|
| methane | CH4 |
| ethane | C2H6 |
| propane | C3H8 |
| butane | C4H10 |
| saturated | this describes compounds in which all carbons have a maximum number of hydrogens attached; C(n)H(2n+2); no double bonds |
| unsaturated | this describes compounds in which there are double bonds; a DOU is introduced each time an H is removed (a pi bond is formed) |
| decreases | stability ______________ as energy increases, reactivity increases, and life time decreases |
| increases | stability ____________ as energy decreases, reactivity decreases, and life time increases |
| induction | this describes how electrons in a sigma bond shift toward a more electronegative atom |
| accept | electronegative substituents, such as oxygen and halogens, will (accept/donate) electron density |
| donate | electropositive substituents, such as alkyl (R) groups, will (accept/donate) electron density |
| resonance | stabilization via ______________ occurs due to delocalization of eletrons/charge; occurs when a +/- charge/lone e- pair is adjacent to a pi bond |
| octet, lowest, electronegative | the major resonance structure is one in which all atoms have a complete _________, have the __________ formal charge, and the negative charge is localized on the most ______________ atom |
| decreases, decreases | ring strain describes what occurs when the angle between two atoms ____________, thus electrons are closer together, and the electron repulsion increases, which _______________ stability |
| nucleophiles | these are compounds that are proton loving; normally electron rich with a full/partial charge; generally a Lewis Base (donates an electron) |
| decreases | nucleophilicity increases as electronegativity ___________ |
| increases | nucleophilicity increases as size ___________ |
| increases | nucleophilicity increases as charge ___________ |
| electrophiles | these are compounds that are electron-loving; generally electron deficiency with a partial/full positive charge; generally a Lewis Acid (accepts electrons) |
| good | __________ leaving groups are stable in a solution, resonance stabilized, weak bases, or neutral compounds |
| bad | _________ leaving groups are unstable in a solution, strong bases, or alkanes |
| isomers | molecules with the same molecular formula |
| constitutional | type of isomer with the same molecular formula but different atomic connectivity and thus different chemical and physical properties; aka. structural |
| conformational | type of isomer with the same molecular formula and atomic connectivity but differ by a rotation of a sigma bond; cannot be isolated (cis/trans) |
| lowest, highest | the staggered (anti) conformation of a molecule is the ____________ energy state, whereas the eclipsed (syn) conformation of a molecule is the _____________ energy state |
| equitorial | substituents on a cyclohexane, especially large ones, are favored to be in the _____________ position in order to reduce steric repulsion |
| chiral | a _____________ molecule is not super-imposable on its mirror image, has no plane of symmetry (has 4 different substituents) |
| chiral center | a _________ __________ (aka. stereocenter) will be a carbon with sp3 hybridization, tetrahedral geometry (no carbanions), and four different substituents |
| D | (D/L) are chiral molecules that rotate plane-polarized light clockwise (+) and are optically active |
| L | (D/L) are chiral molecules that rotate plane-polarized light counterclockwise (-) and are optically active |
| R | in assigning absolute configuration to a molecule, if you trace an arc from the highest priority to the lowest priority group and the loop is clockwise, going towards the right, it is in the ___-configuration |
| S | in assigning absolute configuration to a molecule, if you trace an arc from the highest priority to the lowest priority group and the loop is counterclockwise, going towards the left, it is in the ___-configuration |
| stereoisomer | type of isomer with the same molecular formula and same atomic connectivity, but differ in spatial arrangement of substituents, usually around a chiral center |
| enantiomers | type of isomers that are non-superimposable, mirror images; have the opposite configuration for all chiral centers; chemical and physical properties are identical; can be separated via resolution |
| racemic | a ___________ mixture is a 50:50 mixture of enantiomers; has no optimal activity (0° rotation) |
| equal, opposite | each set of enantiomers has optical rotations of ___________ magnitudes but __________ signs |
| diastereomers | type of isomers that are non-superimposable, non-mirror images of each other; have the opposite configuration for at least one, but not all, chiral centers; all chemical and physical properties are different |
| geometric | type of isomer that is a subset of diastereomers; the molecule is restricted in rotation about a double bond or a ring; doesn't require a chiral center; all chemical and physical properties are different; cis and trans |
| cis, Z | a geometric isomer in which two high priority groups are oriented on the same side of a double bond (give the name and the letter) |
| trans, E | a geometric isomer in which two high priority groups are oriented on the opposite side of a double bond (give the name and the letter) |
| epimers | type of diastereomers that differ in configuration at only one chiral center |
| meso | ______- compounds have stereocenters and an internal plane of symmetry but are not optically active (achiral center) |
| southern | a _________________ blot is used to separate DNA molecules; often used to genotyping different organisms |
| northern | a _________________ blot is used to separate RNA molecules; often used for quantifying gene expression |
| western | a _________________ blot is used to separate proteins; can also be used to quantify gene expression |
| chromatography | a method used to separate molecules over time; employs a stationary phase and a mobile phase |
| stationary | the ________ phase of chromatography acts to retain the compound and is normally a gel |
| mobile | the __________ phase of chromatography acts to move the compound and is normally a fluid |
| higher | if the compound has a _______ affinity to the stationary phase, it is retained longer |
| size exclusion, large, small | - chromatography - separation property = size - used to separate large proteins from small peptides - stationary phase = inert, porous beads - _________ particles elute first - __________ particles elute last |
| thin layer, polar, non-polar | - chromatography - separation property = polarity - for small amts of high HW compounds - stationary phase = silica gel - mobile phase = shallow solvent bath - capillary action - __________ comps. move the least - __________ comps. move the most |
| decrease | the Rf value from thin layer chromatography increases with increasing distance traveled, which denotes a __________ in polarity of the molecule |
| column, non-polar, polar | - chromatography (purifying) - separation property = polarity - for large amts of high HW compounds - stationary phase = silica gel - run mobile (non-polar) phase solvent down - ___________ compounds elute first - ___________ compounds elute last |
| HPLC | - chromatography (analytical and purifying) - separation property = polarity - for large amts of high HW compounds - normal and reverse types |
| normal, non-polar, polar | in a _________ HPLC - stationary phase = polar - mobile phase = non-polar - ___________ compound elutes first - ___________ compound elutes last |
| reverse, polar, non-polar | in a _________ HPLC - stationary phase = non-polar - mobile phase = polar - ___________ compound elutes first - ___________ compound elutes last |
| ion exchange | - chromatography - separation property = charge states - separates amino acids, proteins, and nucleotides - stationary phase = resin with anion/cation groups - mobile phase = buffered solution |
| cationic | when the resin (stationary phase) in ion exchange chromatography is __________, cations elute first |
| anionic | when the resin (stationary phase) in ion exchange chromatography is __________, anions elute first |
| affinity | - chromatography - separate property = lock-and-key interactions - separates proteins from a biological mixture - "immuno" type used for binding antibodies to proteins in a blood serum - "metal ion" type tags C or N term of a protein --> elutes 1st |
| gas | - chromatography - separation property = volatility/boiling pt (BP) - for small amts. of low BP compound - stationary phase = liquid absorbent - mobile phase = gas stream |
| increases | as volatility ____________, boiling point decreases |
| lowest, highest | in gas chromatography - compound with the ___________ boiling point elutes first - compound with the ___________ boiling point elutes last |
| distillation | - property of separation = volatility/ boiling pt. (BP) - purification method - for large amts of low BP compounds - 2 types: simple and fractional |
| increases | as the intermolecular forces of a compound increase, boiling point ________________ |
| increases, decreases | as branching increases, surface area ____________, therefore IMFs decrease and boiling point ____________ |
| simple | ___________ distillation is used to remove impurities from relatively pure liquid and is applicable with the compound's boiling point is > 30° C |
| fractional | ___________ distillation is useful in separating diastereomers; applicable when a compounds boiling point is <30°C |
| solvent extraction | - separation property = solubility in polar/non-polar solutions - used for high MW compounds with acidic/basic groups |
| carboxylic | for extractions, aqueous NaHCO3 (weak base) only deprotonates _____________ acids |
| phenols | for extractions, aqueous NaOH (strong base) deprotonates both ____________ and carboxylic acids |
| amines | for extractions, aqueous HCl (strong acid) protonates __________ |
| resolution | - this method separates enantiomers of a racemic mixture - converts them into diastereomeric salts with chiral resolving agents - separating salts uses conventional means, such as recrystallization |
| mass spectrometry | - this method of analysis is used to determine the MW of a compound - also determines the elemental and isotropic composition of it |
| UV/Visible spectroscopy, blue | - this method of analysis indicates the presence of a conjugated pi system in a molecule - as conjugation increases; λ absorbed increases = red-shift - as conjugation decreases; λ absorbed decreases = _____-shift |
| IR spectroscopy | - this method of analysis indicates the type of functional groups in a molecule - often used to monitor reaction progress - peaks are expressed in wave numbers |
| OH | the _____ functional group appears as a wide peak around 3200 - 3600 on an IR spectroscopy |
| C=O | the _____ functional group appears as a sharp, deep peak around 1700 on an IR spectroscopy |
| C-O | the _____ functional group appear as a semi-sharp, semi-deep peak around 1650 on an IR spectroscopy |
| C≡N/C≡C | the _____/_____ functional group appears as small humps around 2100-2260 on an IR spectroscopy |
| peaks | the number of __________ (signals) on a H NMR spec. represents the number of sets of non-equivalent hydrogens |
| splitting | the ____________ pattern (n+1) on a H NMR spec. represents the number of hydrogens on the adjacent atom |
| area | the ___________ under the peaks on a H NMR spec. represents the number of hydrogens represented by that signal |
| shift | the chemical _______ (ppm) on a H NMR spec. represents the chemical environment of the hydrogens |
| nucleophilic | ____________ substitution reactions are substitution reactions that exchange an atom/substituent with a nucleophile |
| negative, donate | nucleophiles have a more _________ charge, which is why they are better able to ________ an electron pair |
| positive, accept | electrophiles have a more ________ charge, which is why they are better able to _________ and electron pair |
| weaker | the ________ the base, the better the leaving group |
| SN2 | _____ rxns - 1 step: a simultaneous backside, nucleophilic attack + leaving group loss - pentavalent ‡ - inverted stereochem. - rate = k[E+][Nu-] --> affected by Nu-, favors strong, small Nu- - solvent: polar, aprotic (eg. DMSO, acetone, DMF) |
| alcohols | ________ and ethers may also undergo substitution, but require acid catalysis to make the OH group a good leaving group |
| SN1 | _____ rxns - 2 steps: form carbocation intermed(rate-limiting step) ---> Nu- sub. - fastest for 3° C - N/A for 2° and 1° C - racemization of configuration - rate = k[E+] --> not affected by Nu- - solvent: often Nu-, polar protic (eg. H2O, alcohol) |
| carbonyl, ketones, decrease | alcohol oxidation: - makes a ______ group (C=O) - aldehydes and _______ are commonly formed through alcohol oxidations - increase in C-O bonds and ________ in C-H bonds - oxidizing agents: PCC, anything with Cr (CrO3, H2CrO4) |
| carboxylic | a primary alcohol undergoes an alcohol oxidation reaction to first form an aldehyde and further undergoes alcohol oxidation to form a _________________ acid |
| ketone | a secondary alcohol undergoes an alcohol oxidation reaction to form a ___________ |
| no | does an alcohol oxidation occur to tertiary alcohols? |
| electrophile, acidic | carbonyls (C=O) have both resonance and induction, which causes a positive charge to build up on the carbonyl carbon ∴ the carbonyl C acts as an ____________ ∴ the alpha-C, which is adjacent to the carbonyl C is (acidic/basic) |
| tautomerism | this is the equilibrium between keto- (aldehyde/ketones) and enol- forms of a molecule |
| thermodynamic | (thermodynamic/kinetic) enolate is more substituted, more stable, and can preferably form with a strong base and at high temperatures |
| kinetic | (thermodynamic/kinetic) enolate is less substituted, less stable, forms faster because the alpha carbon is less bulky, and can preferably form with a bulk base (LDA) and at cold temperatures |
| sigma | in a nucleophilic addition reaction, you break 1 pi bond and form 2 _________ bonds |
| irreversibly | for a nucleophilic addition reaction with a strong nucleophile, the nucleophile adds _______________ |
| reversible | for a nucleophilic addition reaction with a weak nucleophile, the nucleophile adds _______________ |
| hydride | for __________ reactions, a :H- reacts with the carbonyl group of an aldehyde or ketone to give rise to an alcohol; reducing agents are :H- donors and typically contain B (NaBH4) or Al (LiAlH4) |
| organometallic | _______________ reagents, such as a grignard reagent, act as carbocations and therefore are strongly nucleophilic and basic |
| imine | an _____________ forms when a primary amine (RNH2) is the nucleophile; the reaction is a condensation reaction; =O --> =NHR |
| enamine | an _____________ forms when a secondary amine (R2NH) is the nucleophile; the intermediate of the reaction is an iminium ion; these products are acidic at their alpha carbons; =O --> =NR2 |
| aldol | an __________ reaction occurs a nucleophilic enolate reacts with an aldehyde or a ketone to form a beta-hydroxy carbonyl which can then be irreversibly converted via a condensation reaction into an alpha,beta- unsaturated carbonyl; can be reversed |
| esterification | in an ______________ reaction, an organic acid (RCOOH) is combined with an alcohol (ROH) to form an ester (RCOOR)and water |
| saponification | a ______________ reaction is a process of cleaving esters into carboxylate salts and alcohols by the action of aqueous alkali (OH-); type of hydrolysis; generally irreversible; makes soap |
| anyhdride | an acid __________, a type of carboxylic acid derivative, can be synthesized from an acid chloride + carboxylate |
| halide | an acid __________, a type of carboxylic acid derivative, cannot be synthesized from any other carboxylic acid derivatives; it is the most reactive of the carboxylic acid derivatives; general reducing agents used to form this is SOCl2 or PX3 (X = Br, Cl) |
| ester | an __________, a type of carboxylic acid derivative, can be synthesized from an acid halide/acid anhydride + alcohol |
| amide | an __________, a type of carboxylic acid derivative, can be synthesized from an acid halide/acid anhydride/ester + amine; it is the least reactive of the carboxylic acid derivatives; cannot be made from carboxylic acids directly |
| L | in a fischer projection, the _____ conformation has the highest priority group pointing to the left |
| D | in a fischer projection, the _____ conformation has the highest priority group pointing to the right |
| L | ____- amino acids are naturally occurring |
| strecker | in ________ amino acid synthesis - nonstereoseletive synthesis - R group of the amino acid comes from the aldehyde - Process: imine formation --> nucleophilic addition --> make COOH group via hydrolysis |
| malonic | in the gabriel-_________ synthesis of amino acids - nonstereoselective synthesis - R group comes from an alkyl halide - Process: synthesize N-phthalimidomalonic ester --> add malonic ester (SN2) --> add alkyl halide --> + H3O+ --> decarboxylation |
| >, < | for a strong acid - Ka _____ 1 - pKa _____ 0 |
| <, > | for a weak acid - Ka _____ 1 - pKa _____ 0 |
| pI | ____ = pH at which an amino acid has no electric charge (it is a zwitterion) |
| spontaneous, enzyme | the formation of a peptide bond, aka. an amide bond, forms through an addition-elimination reaction (dehydration) and is NOT ______________ ∴ it requires an __________ |
| resonance | due to _________, a peptide bond acquires 1. a partial double bond character 2. cannot rotate 3. planar 4. amide-H is slightly acidic |
| hydrolysis | peptide bond _____________ is the process that breaks peptide bonds; extremely slow; normally doesn't occur; requires a protease |
| denaturation | ____________ of proteins is the process that disrupts a protein's 3D structure without breaking the peptide bonds; achieved via high temperatures, extreme pHs, change in salt concentration, or urea |
| saponification | fatty acids can be broken down into glycerol and sodium salts via the reaction called _______________ |
| micelles | fatty acids are amphipathic ∴ when they are placed in water, they circle up with the tails pointing in and the heads pointing up, forming a structure called a __________ |
| saturated | ___________ fatty acids pack together better ∴ they form solids |
| unsaturated | cis-______________ fatty acids don't pack well together ∴ increase fluidity ∴ form liquids |
| D | ____-sugars are naturally occurring |
| L | if the carbohydrate is not shown in the fischer projection, the _____- confirmation is assumed if the penultimate carbon is in the S configuration |
| D | if the carbohydrate is not shown in the fischer projection, the _____- confirmation is assumed if the penultimate carbon is in the R configuration |
| penultimate, carbonyl | the cyclization of a sugar occurs by the OH group on the ___________ carbon attacking the ___________ carbon |
| hemiacetal | if the cyclic sugar is a _____________ - in equilibrium with the linear carbon form - mutarotation occurs - is considered a reducing sugar |
| acetal | if the sugar is an ____________ - it is not in equilibrium with its linear form - mutarotation does not occur - is not a reducing surgar |
| carbonyl | you can determine if a sugar is a reducing sugar (hemiacetal) by looking at the ____________ carbon |
| alpha | is the sugar is an _________-anomer, then the OH on the penultimate carbon and the OH on the carbonyl carbon point in opposite (anti) directions |
| beta | if the sugar is a _________-anomer, then the OH on the penultimate carbon and the OH on the carbonyl carbon point in the same (syn) directions |
Created by:
coletty218
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