DAT Organic Chemistry

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Extraction
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Separates dissolved subs. Based on differential solubility in aqueous vs. organic solvents
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Filtration
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Separates solids from liquids
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Recrystallization
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Separates solids based on diff. solubilities; temperature is important
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Sublimation
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Separates solids based on their ability to sublime
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Centrifugation
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Separates large things (ex. Cells, organelles, macromolecules) based on mass and density
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Distillation
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Separates liquids based on boiling point (depends on intermolecular forces)
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Chromatography
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Uses stationary and mobile phases to separate compounds based on how tightly they adhere (generally due to polarity, but sometimes size as well)
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Electrophoresis
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Used to separate biological macromolecules (such as proteins or nucleic acids) based on size and sometimes charge
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Simple Distillation
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Separate liquids that boil BELOW 150C (at least 25C apart)
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Vacuum Distillation
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Seperate liquids that boil ABOVE 150C
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Boiling Point Trends
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1. Increases with chain length due to dispersion forces 2. Decreases with branching
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Melting Point Trends
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1. Increases with branching because the molecules can pack tightly 2. Increases with chain length again due to dispersion forces
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Chemical Lab Test: Concentrated H2SO4
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– Alkenes, alkynes, and alcohols dissolve when added to cold H2SO4 -Alkanes and alkyl halides are insoluble
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Chemical Lab Test: Br2/CCl4
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-Alkenes and alkynes give a positive test, in which the orange-brown color of Br2/CCl4 decolorizes
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Chemical Lab Test: Dilute KMnO4
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-Alkenes and alkynes give a positive test, the deep purple KMnO4 becomes brown
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Chemical Lab Test: AgNO3 in alcohol
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-This is a test for alkyl and allylic halides. A precipitate of AgX is formed
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Chemical Lab Test: Ag(NH3)2OH
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-This is a test for alkynes with terminal triple bonds
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Chemical Lab Test: Iodoform Test I2/OH-
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– A methyl ketone or methyl carbinol give a positive test. A yellow precipitate of CHI3 (iodoform) forms
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Chemical Lab Test: Tollens Test
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-Primarily a test for aldehydes. We use Ag(NH3)2+. The walls of the reaction flask become coated with a “mirror of silver.” Sometimes Ag2O is written with NH3(aq)
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Chemical Lab Test: Chromate Oxidations
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-Primary and Secondary alcohols are oxidized. The reddish-orange dichromate or chromate agent gives a greenish solution. Jones oxidation gives the same result
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Formula: Alkanes
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C(n)H(2n+2)
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Formula: Alkenes
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C(n)H(2n)
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Formula: Alkynes
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C(n)H(2n-2)
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Formula: Cycloalkanes
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C(n)H(2n)
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Carbocation Stability
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3* > 2* > 1* > Methyl
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Radical Stability
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3* > 2* > 1* > Methyl
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Carbanion Stability
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Me > 1* > 2* > 3*
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Branching usually _________ boiling point, but usually _________ the melting point
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1. decreases b.p (because it lowers the surface area) 2. increases m.p
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Ranking Priority for Functional Groups:
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1. Carboxylic Acid Derivatives 2. Aldehydes 3. Ketones 4. Alcohols 5. Amines 6. Alkenes/Alkynes
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__________ compounds have non-superimposable (non-identical) mirror images called ____________
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1. Chiral 2. Enantiomers
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__________ compounds have mirror images that are superimposable (identical)
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Achiral
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Are chiral compounds optically active?
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Yes
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Are racemic mixtures optically active?
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No
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Sn2 Rate
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rate = k[substrate][nucleophile]
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Sn1 Rate
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rate = k[substrate]
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E2 Rate
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rate = k[substrate][base]
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E1 Rate
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rate = k[substrate]
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Electron donators / Activators (strongest to weakest):
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-O-, -NR2, -NH2, -OH, -OR, -R
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Electron Withdrawers / Deactivators (strongest to weakest):
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-NO2, -NR3+, -NH3+, -SO3H, -CN, -CO2H, -CO2R, -COH, -X
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All __________ AND halogens are ortho-para directors
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Activators
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____________ (not halogens) are meta-directing
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Deactivators
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Sn2 reactions have a ______________ transition state (not intermediate)
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Pentavalent
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An antiperiplanar confirmation is associated with what kind of reaction?
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E2
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What is Ag(NH3)2 + used for?
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Tollen’s Reagent – used as a “test” for the presence of aldehydes. Oxidizes aldehydes into acids
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A ____________ is a constant boiling mixture that is made up of substances in a certain ratio that simple distillation cannot separate
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Azeotrope
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Type of Reaction: Alkenes
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Electrophilic Subsititution
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Type of Reaction: Alkanes
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Radical Substitution
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Type of Reaction: Esters
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Nucleophilic Acyl Substitution
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Type of Reaction: Ketones
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Nucleophilic Addition
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Type of Reaction: Aromatics
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Electrophilic Substitution
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Which electrophilic substitution reaction is reversible?
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Sulfonation
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What is the joining of glucose + fructose called?
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Sucrose (which makes it a non-reducing sugar, contains an acetal linkage, and it will NOT mutarotate)
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Oxidizing agent that oxidizes 1* alcohols into aldehydes and 2* alcohols into ketones?
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PCC
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A conjugated diene is when the double bonds are separated by ________ single bond
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one
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An __________ carbon is a carbon atom bonded to a carbon atom that in turn is doubly bonded to another carbon atom
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Allylic
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What functional group molecule is derived from a carboxy acid?
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Ester
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During the bromination of benzene, which catalyst is employed?
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FeBr3
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Grignards will react with anything with an acidic hydrogen available – which group doesn’t have an acidic hydrogen?
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Ethers (ex: Diethyl Ether)
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If two compounds boil within a few degrees of one another, a _____________ distillation would be a likely technique for separation
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Fractional
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Acidity of functional groups?
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Aromatic Acids > Carboxy Acids > Alcohols > Ketones ….. then Aldehydes > Alkynes > Alkenes > Alkanes
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What kind of fatty acids are found in great abundance in animal fat?
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Saturated fatty acids (high mp)
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What kind of fatty acids are found in fish and plant oils?
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Unsaturated fatty acids (low mp, fluid-like, “kinked”)
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___________ are diastereomers in which the two molecules differ in configuration about one carbon?
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Epimers
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Nitriles react with Grignards to give what?
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Ketones
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What device is used to measure the effect of plane-polarized light on optically active compounds (enantiomers)?
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Polarimeter
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Diastereomers have different physical properties, unlike __________
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enantiomers
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What method would MOST effectively separate two volatile compounds?
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Gas-Liquid Chromatography
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Why must Grignard reactions be performed in aprotic solvents?
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Grignard reagents are strongly basic and react violently with protic solvents
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SOCl2
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thinoyl chloride

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