Term
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Definition
| (1) Hydroxybenzene, C6H5OH. (2) Family of compounds characterized by a hydroxyl group on an aromatic ring, ArOH |
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Term
| Diazotization of an amine |
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Definition
| The reaction of a primary aromatic amine with nitrous acid, HNO2 , which forms a diazonium ion, R-N+≡N: and can be used to prepare aryl halides, phenols, and aryl cyanides, or to deaminate the amine |
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Term
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Definition
| Simple phenols, ArOH, are weak acids with pKa ≈ 10 and they are deprotonated by aqueous NaOH to form phenoxide anions, ArO-. |
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Term
| Williamson ether synthesis |
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Definition
| Synthesis of an unsymmetrical ether by alkylation of an alkoxide anion, RO-, with a primary alkyl halide, R' X (or with an alkyl sulfate or alkyl sulfonate), which reacts by an SN2 mechanism: RO- + R' X → ROR' + X- |
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Term
| Electrophilic aromatic substitution |
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Definition
| Replacement of a hydrogen on an aromatic ring by a strong electrophile |
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Term
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Definition
| Carboxylation of phenolate anions with carbon dioxide to form salicylic acids, or o-hydroxy benzoic acids. Also called the Kolbe-Schmitt Reaction. |
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Term
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Definition
| The conversion of allyl phenyl ethers to o-allyl phenols by a sigmatropic rearrangement, which proceeds via a cyclohexadienone intermediate. Also, the conversion of allyl vinyl ethers to γ,δ-unsaturated carbonyl compounds by a sigmatropic rearrangement |
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Term
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Definition
| A derivative of cyclohexadienedione, usually 1,4-benzoquinone (para-quinone); oxidation of a 1,4-benzenediol (hydroquinone) derivative will produce apara-benzoquinone derivative |
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Term
| Nucleophilic aromatic substitution |
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Definition
| Two-stage substitution that involves addition and elimination reactions of an aromatic compound; in the addition stage, the nucleophile adds to the carbon that bears the leaving group; in the elimination stage, the leaving group is expelled. Also called SNAr reaction. |
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Term
| Addition-elimination mechanism |
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Definition
| Two-stage mechanism for nucleophilic acyl substitution reactions and nucleophilic aromatic substitution (SNAr) reactions; in the addition stage, the nucleophile adds to the carbon that bears the leaving group, then in the elimination stage, the leaving group is expelled |
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Term
| Meisenheimer intermediate |
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Definition
| A cyclohexadienyl anion that is resonance stabilized by delocalization of electrons, which is formed during a nucleophilic aromatic substitution (SNAr) reaction by an addition-elimination mechanism |
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Term
| Elimination-addition mechanism |
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Definition
| Two-stage mechanism for nucleophilic aromatic substitution; in the first stage, an aryl halide undergoes elimination to form an aryne intermediate, such as benzyne, then in the second stage, nucleophilic addition to the aryne yields the product of the reaction |
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Term
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Definition
| A species that contains a triple bond within an aromatic ring, such as benzyne |
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Term
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Definition
| Dehydrobenzene, C6H4 , in which benzene lacks two hydrogens and has an additional pi bond that results from sideways overlap of two sp2 orbitals on adjacent atoms of the ring (usually drawn with a triple bond replacing a double bond); it is a very unstable and highly reactive aromatic intermediate in an elimination-addition mechanism |
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