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176 Cards in this Set
- Front
- Back
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amide
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carbonyl and amine
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geminal dihalide
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carbon with two halogens bonded to it
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vicinal dihalide
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two adjacent carbons both bonded to halogens
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alkoxy
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-OR
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hemiacetal
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carbon with an -OH and -OR group along with one -R group
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hemiketal
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carbon with an -OH and -OR group along with two -R groups
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mesyl group
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sulfur with single bonded methyl group and two double bonded oxygens
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tosyl group
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sulfur with single bond to aromatic cyclohexane group and two double bonded oxygens
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acetyl group
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carbon with a carbonyl group as well as a terminal methyl group
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acyl group
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carbon with a carbonyl group and an R group
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anhydride group
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Two carbons each connected to R groups as well as carbonyls, connected together via an oxygen
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aryl group
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aromatic cyclohexane
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benzyl group
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aromatic cyclohexane bonded to a methyl group
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hydrazine
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two nitrogens bonded together via single bonds
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hydrazone
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nitrogen double bonded to an R group as well as a single bond to another nitrogen
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vinyl group
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two double bonded carbons
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vinylic group
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two double bonded carbons with a halogen bonded to one
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allyl
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two double bonded carbons with a methyl group bonded to one
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nitrile
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carbon triple bonded to a nitrogen
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enamine
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carbon single bonded to an R group and single bonded to an NRH, and double bonded to a CR2.
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imine
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a tautomer of en enamine, wherein the double previously double bonded CR2 group's double bond shifts to a single bond, providing electrons for a C=N-R group to be created
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oxime
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carbon single bonded to two R groups, and a =N-OH group.
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nitro
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carbon single bonded to one oxygen and double bonded to another
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nitroso
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a nitrogen double bonded to an oxygen
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conformational isomers
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different spatial arrangements of the same molecule. rotations around a sigma-bond
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structural isomers
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same molecular formula but different bond-to-bond connectivity
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chirality
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molecules that differ in reflections
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achiral
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exactly the same reflections of molecules
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dextrotorary
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rotates plane polarized light clockwise
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levorotary
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rotates plane polarized light counter clockwise
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stereoisomers
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two molecules with the same molecular formula and the same bond-to-bond connectivity that are not the same compound
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what are two examples of stereoisomers?
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enantiomers and diastereomers
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what is resolution?
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the separation of enantiomers
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how do enantiomers relate chemically and physically?
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they have the same chemical and physical characteristics except with reactions with other chiral compounds and reactions with polarized light
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what are diastereomers?
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they have the same molecular formula, have the same bond-to-bond connectivity, are not mirror images of eachother and are not the same compound
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what is a geometric isomer?
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they exist due to hindered rotation about a bond. Cis-isomers and Trans-isomers are examples
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Do geometric isomers have different physical properties?
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Yes they do.
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Which, cis or trans, have a dipole moment?
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cis has a dipole moment, while trans does not.
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Which has stronger intermolecular forces?
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Cis has stronger forces due to the dipole moment.
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What does stronger intermolecular forces pertaining to geometric isomers infer about their physical properties?
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Cis molecules have higher boiling points
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What does a lack of symmetry among cis molecules infer about their physical properties?
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They are unable to form crystals as readily due to their lack of stackability
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Which has higher heats of combustion due to steric hindrance?
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Cis molecules have higher heats of combustion because they have higher energy levels due to steric hindrance
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Do diastereomers have different physical properties?
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They have different rotation of plane-polarized light, as well as different melting and boiling points as well as solubilities.
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What is the maximum number of optically active isomers found via?
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The equation is 2^n, where n is the number of chiral centers
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What are meso compounds?
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They are compounds where two chiral centers can offset eachother creating an optically inactive molecule
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Are meso compounds achiral?
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Yes
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Why are meso compounds considered achiral?
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Because they have an internal plane of symmetry
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What are epimers?
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They are diastereomers that differ at only one chiral carbon
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What are anomers?
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They are the two possible diastereomers that form during an epimeric ring closure.
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What is the chiral carbon of an anomer called?
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Anomeric carbon
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When the hydroxyl group on the anomeric carbon on glucose is oriented in the opposite direction to the methyl group, what is the anomer labeled as?
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alpha
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What about when the hydroxyl group is in the same direction?
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It is labeled beta.
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What governs boiling point trends in alkanes?
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Intermolecular forces
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When carbons are added to a single chain alkane, the molecular weight goes up increases intermolecular forces concurrently. What happens to the boiling point?
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It goes up.
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What does branching do to boiling point in alkanes?
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It lowers the boiling point
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Does melting point go up or down in alkanes with increased molecular weight?
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It goes up
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What does branching due to melting point of alkanes?
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It increases it
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Are alkanes soluble in water?
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No
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What are alkanes soluble in?
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They are solube in benzene, carbon tetrachloride, chloroform, and other hydrocarbons
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If an alkane contains a polar functional group, what happens to the polarity of the entire molecule and its solubility as the carbon chain is lengthened?
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It goes down
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Do alkanes have low density?
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Yes
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What happens during combustion?
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An alkane reacts with oxygen, producing CO2, H2O and most importantly heat
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Is combustion spontaneous?
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No, it requires heat to occur, usually via a flame.
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What type of reaction is combustion?
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It is a radical reaction
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If a molecule has a high heat of combustion, is it more or less stable than a similar molecule with a smaller heat of combustion?
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A high heat of combustion correlates to the energy level of a molecule, inferring a less stable molecule
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What happens if you react an alkane with F, Cl, and Br in the presence of heat or light?
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Halogenation
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Well what happens first in halogenation?
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The first step is initiation.
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What happens during initiation?
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Light or heat cleaves a covalent bond between a two bound halogens. They both split leaving two identical radicals
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What happens to these radicals after that, and what is the step called?
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The next step is called propagation, and what happens is the halogen radical removes a hydrogen from the alkane, resulting in an alkyl radical.
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What can this alkyl radical do to get rid of its radicalness?
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It can hookup with a diatomic halogen molecule creating an alkyl halide and a new halogen radical.
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Is this the end of our halo-radicals?
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No! This reaction can continue indefinately, or it can go through the third and final step of halogenation.
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What the third and final step of halogenation?
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Termination
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So what exactly happens in the termination step of halogenation?
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Several things could happen. Two akyl radicals could react, the last halo-radicals can react with alkyl-radicals to form alkyl halides, or two halo-radicals can hookup
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Is halogenation an endothermic or exothermic process?
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It is exothermic
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What is the stability chart for an alkyl radical?
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3>2>1>Methyl
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What type of geometry do alkyl radicals exhibit?
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They exhibit trigonal planar geometry
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When is the majority of product formed during halogenation?
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The majority of the alkyl halides are formed during propagation
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Are Pi-bonds more or less stable than Sigma-bonds?
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They are less stable
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Does this mean alkenes are more or less reactive than alkanes?
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They are more reactive.
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When dealing with alkenes, what should I keep in mind about the Pi-bonds?
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They are electron hungry
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What does this infer about acidity values of alkenes versus alkanes?
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Alkenes are more acidic as a result of the willingness to gain electrons
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What happens when a proton is moved away from a Pi-bond?
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The Pi-bond of the alkene absorbs some of the negative charge
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What does this do to the conjugate base?
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It stabilizes it
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How does substitution relate to thermodynamic stability of alkenes?
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They more highly substituted, the more stable the alkene.
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You're wrong! How come when you have addition reactions dealing with electrophiles the most substituted are the most reactive, it should be the opposite right?
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Well a paradox exists due to the carbocation intermediate. A tertiary alkene will be a more stable carbocation, so it will proceed with greater frequency.
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So which is right?
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When dealing with electrophilic addition reactions of alkenes, the most reactive are the more substitituted
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How do physical properties of alkenes work?
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They work the same way as alkanes
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Are alkenes soluble in water?
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Slightly, and they have a lower density than water.
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Which is more acidic, alkanes or alkenes?
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Alkenes
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What happens in an elimination reaction?
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One or two functional groups are eliminated or removed to form a double bond.
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What type of reaction is dehydration of an alcohol?
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It is an E1 reaction
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What happens in dehydration of alcohol reactions?
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An alcohol forms an alkene in the presence of hot concentrated acid
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Since it's an E1 reaction, that means it depends on the concentration of only one reactant, but which reactant does it depend on, the acid or the alcohol?
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It depends on the concentration of the alcohol in this case.
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What happens in the first step of dehydration of alcohols?
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The acid protonates the hydroxyl group
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What does this produce, and what was the purpose of protonating this new thing?
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It produces water, which is a good leaving group. It wants to dump off the compound.
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What happens next, and whats so special about this step?
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This is the rate-determining step- the water drops off, forming a carbocation
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Woo, carbocation. When I see carbocation I should think what?
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Rearrangement possibilities exist, and stability of intermediate
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What does carbocation stability follow the trend of?
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It follows th same trend as radical stability?
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What's that trend again?
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3>2>1>methyl
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So when would rearrangement occur?
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It would only occur if a more stable carbocation could be made
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What happens in the final step of dehydration of an alcohol?
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A water molecule deprotonates the carbocation and the alkene is formed
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What will the predominant product be a result of?
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It will be the more stable, most substituted alkene.
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What does the Saytzeff rule say?
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It says that the major product of elimination will be the most substituted alkene.
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What is dehydrohalogenation?
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It's what happens when you take an alkane with a halogen and dump the halogen off in favor of making an alkene.
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What are the two possibility routes for dehydrohalogenation to occur?
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It can occur via E1 or E2
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When would dehydrohalogenation occur via E1?
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It would happen if a strong base is there
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When would dehydrohalogenation occur via E2?
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It would happen is there is a high concentration of a strong, bulky base
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What happens first in the E1 reaction?
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The halogen drops off in the first step.
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What happens second in the E1 reaction?
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The hydrogen is removed in the second step via the weak power of our weak base.
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So the E1 reaction is multi-step or single-step?
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Multi
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What happens in E2 reaction?
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The base removed a proton from the carbon next to the halogen-containing carbon and the halogen drops off, leaving an alkene.
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So is the E2 reaction single or multi-step?
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It is single step.
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What does the bulky base of this E2 mechanism prevent?
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It prevents an SN2 reaction, but if the base is too bulky, the Saytzeff rule is violated, leaving the least substituted alkene.
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So what's an important thing to notice about the difference between these two pertaining to the power of the bases?
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Well the E2 mechanism has a strong base, and it's so pimped out that it can pull the hydrogen off even without the decreased stability of an intermediate state like what occurs in the E1 mechanism.
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What type of reaction of catalytic hydrogenation?
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It is an addition reaction?
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What type of catalyst is used in catalytic hydrogenation?
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A heterogenous catalyst
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What type of addition occurs usually?
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Syn-addition
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What are possible catalysts?
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Ni, Pd, or Pt
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So what actually happens?
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You take an alkene and you turn it into an alkane
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Is hydrogenation an endothermic or exothermic reaction?
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It is an exothermic reaction.
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Is it spontaneous?
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No, it has a high energy of activation
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What are heats of hydrogenation used to measure?
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They are used to measure the relative stabilities is alkenes.
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If something has a low heat of hydrogenation, is it unstable?
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No it is considered stable
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What happens with syn addition of an alkynes via hydrogenation?
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It creases a cis alkene.
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What does oxidation of an alkene produce?
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It may produce glycols or it may cleave the alkene at the double bond
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What is an example of a cleavage such as this?
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Ozonolysis
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If you add 1) O3 and 2) Zn,H2O, what happens to an alkene?
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It will cleave the alkene at the double bond, producing two carbonyl groups
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What happens to alkynes when they undergo ozonolysis?
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They produce carboxylic acids
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What is an electrophile?
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It is an electron-loving species
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What types of things are usually electrophiles?
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Things with a positive charge, even if it is only from a momentary dipole.
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What does the double bond of alkene function as pertaining to electrophiles?
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It is an electron-rich environment, which will attract electrophiles
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What rule is followed when you had a hydrogen halide to an alkene?
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Markovnikov's rule
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What does Markovnikov's rule state?
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It states the hydrogen will add to the least substituted carbon of the double bond
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What is the first step of electrophilic additition of a hydrogen halide to an alkene?
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The hydrogen halide is a Bronsted-Lowry acid, so it will create a positively charged proton, which acts as an electrophile.
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What is the second step of electrophilic additition of a hydrogen halide to an alkene?
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The newly formed carbocation picks up the negatively charged halide ion.
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Which is the slow step?
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The first step is the slow step, and it determines the rate
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What happens during this reaction is peroxide (ROOR) is present?
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Bromine will add to the least substituted carbon
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What is this known as?
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Anti-markovnikov addition.
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Will the other halides perform anti-markovnikov addition?
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No, they still do Markovnikov, even in the presence of ROOR.
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What are the most reactive alkenes, and why?
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The most reactive are the most thermodynamically stable, because they also have the lowest activation energy and form carbocations the easiest.
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What is hydration of an alkene?
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It takes place when water is added to an alkene in the presence of an acid.
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Does hydration of an alkene follow Markovnikov's rule?
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Yes it does.
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What is this reaction the reverse of?
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It is the reverse of dehydration of an alcohol.
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What circumstances drive an alkene toward alcohol formation?
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Low temperatures and dilute acid
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What circumstances drive an alcohol toward alkene formation?
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High temperatures and concentrated acid
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What is oxymercuration/demercuration?
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It is another reaction which creates an alcohol from an alkene
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Is oxymercuration/demurcuration a one or two step process?
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Two step process
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Does it usually result in rearrangement of the carbocation?
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Very rarely.
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What happens in the first step of oxymercuration/demurcuration?
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The mercury-containing reagent partially dissociates to +Hg(OAc)
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What does the +Hg(OAc) do once its formed?
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It acts as an electrophile creating a mercurinium ion
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What does water do to the mercurinium ion?
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It attacks the mercurinium ion to form the organomercurial alcohol.
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What type of addition is this?
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Anti-addition
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What is the second step?
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It is the demercuration to form the alcohol
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How is this performed?
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By the addition of a reducing agent and base.
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What is hydroboration?
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It is another mechanism to produce an alcohol from an alkene
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Does it follow Markovnikov?
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No, it is anti-markovnikov
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What type of addition is it?
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It is syn addition
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So what happens in hydroboration?
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Take an alkene and add a hydrogen and alcohol to the same side of two carbons, via anti-markovnikov.
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What happens if you add Br2 or Cl2 to an alkene?
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They add via anti-addition to form vicinal dihalides
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What is an important difference between a similar reaction involving alkanes?
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Oh, you mean halogenation, right? Well alkene halogenation doesn't require heat or light
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What happens if you perform alkene halogenation in the presence of water?
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Water will act as a nucleophile instead of a bromide/chloride ion.
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What does this produce?
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It produces an anti-addition halohydrin
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Does benzene undergo addition or substition?
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It only undergoes substitution
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Is benzene flat?
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Yes, it has to be considering its aromatic
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What happens when an electron withdrawing group is in the R position of a benzene?
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It deactivates the ring and directs any new substituents to the meta position
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What do electron donating groups do to the wring?
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They active the ring and direct any new substituents to the ortho and para positions.
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What is the exception to this rule, and why?
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Halogens are an exception because they are electron withdrawing and deactivate the ring as expected but they are ortho-para directors.
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effet +M |
attracteur favorise sN en stabilisant cation–O− –NH2 –NR2 –OH –OR –NHC=(O)R –OC=(O)R –(Aryl) (par exemple –phényle) –Br, –Cl, –I, –F Carbanion |
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effet -M |
augmente Ea donc SN plus difficile
–COOR –COOH –CHO –C=(O)R –CN –CH=CH–COOH –NO2 –SO3H Carbocation |
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effet -I |
attracteur
substituants halogénés :-CF3, le groupement trifluorométhyle ;-CCl3, le groupement thichlorométhyle ;et plus généralement tout groupement possédant un ou plusieurs halogènes, ou l'halogène lui-même subsituants azotés :-NH2, le groupement et la fonction amine ;-NO2, le groupement nitro ; substituants possédant un oxygène :-OH, le groupement hydroxyle et la fonction alcool ; substituants carbonés (alcyles ou allyles) :phényle ;CH=CH2, le groupement vinyle ;et plus généralement tout groupement insaturé. |
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effet +I |
les alcalins ou alcalino-terreux:-Na, le sodium;-Li, le lithium;-MgR, les organo-magnésiens; les boranes-BRR'et les groupements alkyles |
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What is phenol?
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It is a benzene with an alcohol substituent.
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What is aniline?
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It is a benzene with an amino substituent.
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What is toluene?
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It is a benzene with a methyl substituent..
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What is benzoic acid?
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It is a benzene with a carboxylic acid
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What is nitrobenzene?
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It is a benzene with a nitro group.
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