Reactions and Reagent Structures of Chp. 16 – Flashcards
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Important: * IDENTIFICATION method; causes decolorization, but SLOWLY * SUBSTITUTION not addition * all THREE double bonds are retained * only works with BROMINE
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benzene + bromine + carbon tetracholoride + ferric bromide --> hyrobromic acid (gas) + bromobenzene
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Important: * NO decolorization (red to clear)
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benzene + bromine + carbon tetrachloride --> no reaction
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Important: * NO decolorization (purple to brown)
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benzene + potassium permanganate + water --> no reaction
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Name the compound (it has two names).
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ferric bromide iron (III) bromide
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Important: * requires MORE ACTIVE CATALYST than just Pt, Pd, etc. * requires HIGHER PRESSURES of H2 * ?H < ?Hº of conjugated DIENE; resonance energy/double bond is amazingly low
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catalytic hydrogenation of benzene benzene + 3H2 --> cyclohexane
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Important: * occurs by extremely FAST DIELS-ALDER reaction * reason why cyclobutadiene has NEVER been isolated and purified
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dimerization of cyclobutadiene monomer
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Name the annulene.
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[4]annulene cyclobutadiene
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Name the annulene compound.
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[8]annulene cyclooctatetraene
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Name the annulene shown in the picture.
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[10]annulene cyclodecapentaene
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Name the aliphatic polyene.
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hexa-1,3,5-triene
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Name the aliphatic polyene shown in the picture.
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buta-1,3-diene
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Draw and name the acyclic counterpart of cyclohexa-1,3-diene.
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cis,cis-hexa-2,4-diene
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Give BOTH names of the cyclic polyene shown in its two most common conformations.
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cyclotetradecaheptaene [14]annulene LEFT: antiaromatic RIGHT: aromatic
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Name the polycyclic compound.
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pyrene
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Name the aromatic polycylic compound.
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napthalene (C10H8) IMPORTANT: * simplest poylnuclear aromatic hydrocarbon (PAH or PNA) * lower resonance energy than benzene * 10 electrons in resonance system * has three Kekulé structures * MOTHBALLS
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Give BOTH names of the cyclic polyene shown in four of its conformations.
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cyclodecapentaene [10]annulene
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Give two names for the compound shown.
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cyclooctadecanonaene [18]annulene
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Give the name of the molecule.
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heptalene
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Give the name of the molecule in the image.
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azulene (an constitutional isomer of naphthalene)
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Give the name of the compound in the image.
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pentalene
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IMPORTANT: * cyclopentadiene has a pKa of 16, near that of water! * must use a really strong base (hydroxide ion wouldn't deprotonate because water is a stronger acid) * note how the cyclopentadienyl anion can be written in shorthand
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cyclopentadiene + tert-butoxide ion --> tert-butanol + cyclopentadienyl anion (aromatic)
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IMPORTANT: * the cyclopenta-2,4-dien-1-ol cation is too unstable for the hydronium to act as a leaving group because the ion is antiaromatic
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cyclopenta-2,4-dien-1-ol + conc. H2SO4 --> protonated cyclopenta-2,4-dien-1-ol [FINAL PRODUCT]
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Name the cation; it has two names.
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tropylium ion cycloheptatrienyl cation
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IMPORTANT: * the tropylium ion is a more stable base than the hydroxide ion
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cycloheptatrienol + aqueous solution of pH tropylium ion
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IMPORTANT: * sp3 hydrogen taken * reaction not favored * barely more acidic than propene * gains only one electron
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cycloheptatriene + very strong base --> cycloheptatrienyl anion + B-H
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IMPORTANT: * forms a hydrocarbon dianion (rare) * cyclooctatetraene gains TWO electrons via the reaction * the hydrogens leave and do not retain any electrons * potassium donates two electrons to the hydrogen cations
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cyclooctatetraene + 2 potassium metal --> cyclooctatetranyl DIANION + 2K+ + H2 (gas)
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Draw the structure of pyridine.
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IMPORTANT: * aromatic * pKb = 8.8 * usually undergoes substitution rather than addition
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Draw the pyridinium ion.
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IMPORTANT: * It is still aromatic. * pKa = 5.2
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Draw the structure of pyrrole
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* pKb = 13.6 * strong acid usually protonates at C2 * when protonated at nitrogen, denoted "N-protonated pyrrole" * N-protonated pyrrole pKa = 0.4
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IMPORTANT: * when imidazole becomes protonated, the nitrogens become chemically equivalent (isoelectronic) due to resonance
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imidazole + acid --> protonated imidazole [resonance] equilibrium
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Draw the structure of purine.
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IMPORTANT: * four nitrogens total * three basic nitrogens * one nonbasic nitrogen * imidazole ring and pyrimidine ring fused together
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Draw the structure of furan.
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IMPORTANT: * once it's hydrogenated, it's known as tetrahydrofuran * the oxygen atom is sp2 hybridized, with one lone pair in a 2p orbital and one lone pair in an sp2 orbital * aromatic
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Draw the structure of thiophene.
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IMPORTANT: * also known as THIOFURAN * sulfur is sp2 hybridized with one lone pair in a 3p orbital and the other lone pair in an sp2 orbital * aromatic
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Give both names of the compound shown.
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ammonia azane
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Name the PAH.
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anthracene (C14H10) IMPORTANT: * can undergo addition reactions * 4 resonance structures
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Name the PNA.
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phenanthrene (C14H10) * can undergo addition reactions * 5 resonance structures
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IMPORTANT: * goes by 1,4-addition to maintain integrity of two isolated, aromatic benzene rings
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anthracene + Br2 in carbon tetrachloride (nonpolar solvent) --> 9,10-dibromo compound
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IMPORTANT: * goes by 1,2-addition to maintain integrity of two isolated, aromatic benzene rings
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phenanthrene + Br2 in carbon tetrachloride (nonpolar solvent) --> 9,10-dibromo compound
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Name the large polynuclear aromatic hydrocarbon.
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benzo[a]pyrene IMPORTANT: * one of the most thoroughly studied carcinogens * found in cigarette smoke * formed whenever organic compounds undergo incomplete combustion * epoxides form and react with DNA
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Name the six-ringed polynuclear aromatic hydrocarbon.
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dibenzopyrene
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pyrimidine + imidazole =
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purine
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benzene + imidazole =
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benzimidazole
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benzene + pyrrole =
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indole
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benzene + pyridine =
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quinoline
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benzene + furan =
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benzofuran
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benzene + thiophene =
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benzothiophene
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Please name the compound; give both its common name and IUPAC name.
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IMPORTANT: it's found in licorice
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Name the compound; give both its common name and IUPAC name.
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IMPORTANT: it's found in Maraschino cherries
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Give three names for the compound.
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propanone, dimethyl ketone, and acetone
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three methyls + benzene
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mesitylene 1,3,5-trimethylbenzene
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two methyls + benzene; meta positioning
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m-xylene 1,3-dimethylbenzene
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one methyl + one hydroxy group + benzene; para positioning
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p-cresol 4-methylphenol
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toluene + acetyl group; ortho positioning
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o-toluic acid 2-methylbenzoic acid
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Give four names for the compound, tricky little bastard.
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benzyl ethyl ether (ethoxymethyl)benzene ?-ethoxytoluene benzoxyethane
