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50 Cards in this Set
- Front
- Back
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Alkyl halide (haloalkane)
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A derivative of an alkane in which one (or more) of the hydrogen atoms has been replaced by a halogen, (p. 212)
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allylic
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The saturated position adjacent to a carbon-carbon double bond. (p. 221)
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allylic halogenation
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Substitution of a halogen for a hydrogen at the allylic position. (p. 221)
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allylic shift
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A rearrangement that results from reaction at either end of a resonance-stabilized allylic intermediate. (p. 222)
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anti
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Adding to (or eliminating from) opposite faces of a molecule. (p. 261)
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anti-coplanar
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Having a dihedral angle of 180° between the hydrogen being abstracted and the leaving group
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syn-coplanar
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Having a dihedral angle of 0° between the hydrogen being abstracted and the leaving group
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aprotic solvent
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A solvent that has no acidic protons; a solvent with no O-H or N-H groups. (p. 234)
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aryl halide
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An aromatic compound (benzene derivative) in which a halogen is bonded to one of the carbon atoms of the aromatic ring. (p. 212)
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base
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An electron-rich species that can abstract a proton. (p. 231)
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basicity (base strength)
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The thermodynamic reactivity of a base, expressed quantitatively by the base-dissociation constant Kb.
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concerted reaction
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A reaction in which the breaking of bonds and the formation of new bonds occur at the same time (in one step). (pp. 227, 259)
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dehydrohalogenation
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An elimination-in which the two atoms lost are a hydrogen atom and a halogen atom. (pp. 225,253)
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electrophile (Lewis acid)
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A species that can accept an electron pair from a nucleophile forming a bond. (p. 226)
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electrophilicìty (electrophile strength)
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The kinetic reactivity of an electrophile.
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elimination
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A reaction that involves the loss of two atoms or groups from the substrate, usually resulting in the formation of a pi bond. (p. 225, 252)
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E1 reaction (elimination, unimolecular)
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A multistep elimination where the leaving group is lost in a slow ionization step, then a proton is lost in a second step. Zaitsev orientation ls generally preferred. (p. 252)
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E2 reaction (elimination, bimolecular)
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A concerted elimination involving a transition state where the base is abstracting a proton at the same time that the leaving group is leaving.
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geminal dihalide
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A dihalide with both halogens on the same carbon atom. (p. 214)
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halogen exchange reaction
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A substitution where one halogen atom replaces another; commonly used to form fluorides and iodides. (p. 229)
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hydride shift (symbolized ~H)
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Movement of a hydrogen atom with a pair of electrons from one atom (usually carbon) to another. Hydride shifts are examples of rearrangements that convert carbocations into more stable carbocations. (p. 246)
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hydroxylic solvent
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A solvent containing OH groups (the most common type of protic solvents). (p. 234)
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inversion of configuration (see also Walden inversion)
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A process in which the groups around a chiral carbon atom are changed to the opposite spatial configuration, usually as a result of back-side attack. (p. 238, 244) The SN2 reaction goes with inversion of configuration.
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leaving group
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The atom or group of atoms that departs during a substitution or elimination. The leaving group can be charged or uncharged, but it leaves with the pair of electrons that originally bonded the group to the remainder of the molecule. (p. 225)
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methyl shift (symbolized ~CH₃)
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Rearrangement of a methyl group with a pair of electrons from one atom (usually carbon) to another. A methyl shift (or any alkyl shift) in a carbocation generally results in a more stable carbocation. (p. 248)
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nucleophile (Lewis base)
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An electron-rich species that can donate a pair of electrons to form a bond. (p. 226, 231)
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nucleophilicity (nucleophile strength)
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The kinetic reactivity of a nucleophile; a measure of the rate of substitution in a reaction with a standard substrate.
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nucleophilic substitution
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A reaction where a nucleophile replaces another group or atom (the leaving group) in a molecule . (p. 225)
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organic synthesis
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The preparation of desired organic compounds from readily available starting materials.
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polarizable
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Having electrons that are easily displaced toward a positive charge. Polarizable atoms can begin to form a bond at a relatively long distance. (p. 232)
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primary halide, secondary halide, tertiary halide
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These terms specify the substitution of the atom (sometimes called the head carbon).If the head carbon is bonded to one other carbon, it is primary; if it is bonded to two carbons, it is secondary; and if bonded to three carbons, it is tertiary. (p. 214)
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protic solvent
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A solvent containing acidic protons, usually O-H or N-H groups. (p. 233)
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racemization
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The loss of optical activity that occurs when a reaction shows neither clean retention of configuration nor clean inversion of configuration. (p. 244)
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reagent
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The compound that serves as the attacking species in a reaction.
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rearrangement
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A reaction involving a change in the bonding sequence within a molecule. Rearrangements are common in reactions such as the SN1 and E1 involving carbocation intermediates. (p. 246)
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retention of configuration
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Formation of a product with the same configuration as the reactant. In a nucleophilic substitution, retention of configuration occurs when the nucleophile assumes the same stereochemical position in the product as the leaving group occupied in the reactant. (p. 244)
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solvolysis
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A nucleophilic substitution or elimination where the solvent serves as the attacking reagent. Solvolysis literally means “cleavage by the solvent.” (p. 240)
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stereocenter
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An atom that gives rise to stereoisomers when its groups are interchanged. Asymmetric carbon atoms and double-bonded carbons in cis-trans alkenes are the most common stereocenters.
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stereospecific reaction
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A reaction in which different stereoisomers react to give different stereoisomers of the product. (pp. 239,262)
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steric hindrance (steric strain)
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Interference by bulky groups when they approach a position where their electron clouds begin to repel each other. (p. 237)
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substitution (displacement)
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A reaction in which an attacking species (nucleophile, electrophile, or free radical) replaces another group. (p. 225)
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SN2 reaction (substitution, nucleophilic, bimolecular)
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The concerted displacement of one nucleophile by another on an sp³ hybrid carbon atom. (p. 227)
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SN1 reaction (substitution, nucleophilic, unimolecular)
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A two-step interchange of nucleophiles, with bond breaking preceding bond formation. The first step is ionization to form a carbocation. The second step is the reaction of the carbocation with a nucleophile. (p. 240)
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substrate
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The compound that is attacked by the reagent. (p. 226)
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syn
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Adding to (or eliminating from) the same face of a molecule. (p. 261)
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transition state
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In each individual step of a reaction, the state of highest energy between reactants and products. The transition state is a relative maximum (high point) on the reaction-energy diagram. (p. 221)
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vicinal dihalide
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A dihalide with the halogens on adjacent carbon atoms. (p. 214)
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vinyl halide
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A derivative of an alkene in which one (or more) of the hydrogen atoms on the double-bonded carbon atoms has been replaced by a halogen. (p. 212)
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Walden inversion (see also inversion of configuration)
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A step in a reaction sequence in which an asymmetric carbon atom undergoes inversion of configuration. (p. 238)
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Zaitsev’s rule (Saytzeff rule)
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An elimination usually gives the most substituted alkene product. Zaitsev’s rule does not always apply, but when it does, the reaction is said to give Zaitsev orientation. (p. 251)
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