Orgo 16.10-16.6

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Orgo 16.10-16.6
2014-01-09 18:41:58
CHM 202
Organic Chemistry
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  1. The __ are composed of two or more fused benzene rings. __ share two carbon atoms and the bond between them

    __ is the simplest fused aromatic compound, consisting of two fused __r rings. 

    The two aromatic rings in __ contain a total of 10 pi electrons. Two isolated aromatic rings would contain 6 pi electrons in each __, for a total of 12. The smaller amount of electrond ensity gives __ less than twice the __ of benzene: 252 kJ/mol, or 126 kJ, per aromatic ring, compared with benzene's resonance energy of 151 kJ/mol.
    • polynuclear hydrocarbons (PAHs or PNAs)
    • fused rings
    • naphthalene
    • aromatic 
    • naphthalene
    • aromatic system
    • naphthalene
    • resonance energy
  2. As the number of )) increases, the __ per ring continues to decreases and the compounds become more __. __ has a __ of 351 kJ/mol, or 117 kJ per aromatic ring. __ has a slightly higher resonance energy of 381 kJ/mol. Each of these compounds has only 14 pi electrons in its aromatic rings, compared with 18 electrons for three separate __.
    • fused aromatic rings
    • resonance energy
    • reactive
    • tricyclic anthracene
    • resonance energy
    • phenanthrene
    • benzene rings
  3. Because they are not strongly stabilized as __, __, and __ can undergo __ reactions that are more characteristic of their  __ relatives. __ undergoes 1,4- addition at the 9- and 10- positions to give a product with two isolated, fully aromatic rings. (Because they are less likely to be __ , the __ atoms of fused aromatics are often left unbranched.)
    • benzene
    • anthracene
    • phenanthrene
    • addition
    • nonaromatic polyene
    • anthracene
    • substituted
    • bridgehead carbon
  4. Larger __ have mure fused rings than __ and __, and they have less __ per ring and are more reactive. In drawing most of these large __, we have to select which __ to use in order to make their rings appear __. There is a high level of interest in the larger __ because they are formed in most combustion processes and many of them are __.
    • polynuclear aromatic hydrocarbons (PAH)
    • anthracene
    • phenanthrene
    • resonance energy
    • PAHs
    • Kekule structures
    • aromatic
    • PAHs
    • carcinogenic
  5. What do you get when you make an extremely large PAH, with millions or billions of benzene rings joined together? 

    Carbon was known to exist as three __ (elemental forms with different properties): __(3)__

    __ refers to charcoal, soot, coal, and carbon black. These materials are mostly microcrystalline forms of graphite. They are characterized by small particle sizes and large surface areas with partially saturated valences. These small particles readily absorb __ and __ from solution, and they form strong, stable dispersions in polymers, such as the dispersion of carbon black in tires.
    • graphite
    • allotropes
    • amorphous carbon
    • diamond
    • graphite

    • amorphous carbon
    • gases
    • solutes
  6. __ is the hardest naturally occurring substance known. __ has a crystalline structure containing tetrahedral carbon atoms linked together in a 3D lattice. This __ extends throughout each crystal, so that a diamond is actually one giant molecule. __ is an electrical insulator because the elctrons are all tightly bound in __ and they are unavailable to carry a __.
    • diamond
    • diamond
    • lattice
    • diamond
    • sigma bonds
    • current
  7. __ has a layered __. Within a layer, the C-C bond lengths are all 1.415 angstroms which are fairly close to the C-C bond length in __. Between layers, the distance is 3.35 Angstroms which is about twice the __ for carbon, suggesting there is little or no bonding between layers. The layers can easily __ and slide across each other, making graphite a good lubricant. This layered structure also helps to explain graphite's unusual electrical properties: It is a good __ parallel to the layers, but it resists __ perpendicular to the layers.
    • graphite
    • planar structre
    • benzene
    • van der Waals radius
    • cleave
    • electrical conductor
    • electrical currents
  8. We picture each layer of graphite as a nearly __. All the valences are satisfied, and no bonds are needed between layers. Only __ hold the layers together, consistent with their ability to )) over one another. THe __ within a layer can conduct electrical currents parallel to the layer, but electrons cannot easily jump between layers, so __ is resistive perpendicular to the layers.
    • infinite lattice of fused aromatic rings
    • van der Waals forces
    • pi electrons
    • graphite
  9. Because of its __, graphite is slightly more stable than __, and the transition from __ to __ is slightly __. Fortunately, the favorable conversion of __ to __ is really slow. Diamond has a higher density than graphite, implying that graphite might be converted to diamond under very high pressures.
    • aromaticty
    • diamond
    • diamond
    • graphite
    • exothermic
    • diamond
    • graphite
  10. __ is a single layer of graphite one atom thick. 

    __ only has only one type of carbon atom by ^13C NMR. ^60C is unusally symmetrical. 

    These compounds are called __.
    A soccer ball has the same structure as C60, with each vertex representing a carbon atom. Allt he carbons are __. Each carbon serves as a __ for two 6-membered rings and one five-membered ring. There are only two types of bonds: what are they?
    • graphene
    • buckminsterfullerene
    • fullerene
    • chemically the same
    • bridgehead
    • 1) the bonds that are shared by a 5-membered ring and a 6-membered ring
    • 2) the bonds shared between two six-membered rings
  11. It appears the six-membered rings are __, but the double bonds are partially localized between the six-membered rings. These double bonds are less reactive than typical __ double bonds yet they do undergo some of the addition reactions of alkenes.
    • aromatic
    • alkene
  12. __ begin with half of the C60 sphere, fused to a cylinder composed entirely of fused 6-membered rings. __ are electrically conductive only along the length of hte tube and they have an enornous __ ratio
    • nanotubes x2
    • strength-to-weight
  13. __ is one of many fused heterocyclic compounds whose rings shared two atoms and the bond between them. The properties of __ are generally similar to those of the simple __. __ compounds are common in nature, and they are also used as drugs to treat several illnesses.
    • purine
    • fused-ring heterocycles
    • heterocycles
    • fused heterocyclic compounds
  14. Many compounds are named as __, with their substituents named just as though they were attached to an alkane. 

    __ are named using the prefixes __, __ and __ to specify the __ patterns. These terms are abbreviated __, __, and __. Numbers can also be used to specify the __ in __.
    • derivatives of benzene
    • disubbed benzenes
    • ortho
    • meta
    • para
    • o
    • m
    • p
    • substitution
    • dissubed benzenes
  15. With three or more substituents on the benzene ring, __ are used to indicate position. 
    How will you number them?
    The carbon atom bearing the __ is assumed to be C1.
    • numbers
    • assign numbers to give the lowest possible numbers to the substituents
    • functional group that defines the base name (as in phenol or benzoic acid) is assumed to be C1
  16. When the benzene ring is named as a substituent on another molecule, it is called a __, which is used in the name just like the name of an __, and it is often abbbreviated __ instead of drawing a complex structure. 

    The __ consisting of a benzene ring and a methylene group is often named __. It has __ carbons.
    • phenyl group
    • alkyl group
    • Ph
    • 7-carbon unit
    • benzyl group
    • 7
  17. Aromatic hydrocarbons are sometimes called __. An __, abbreviated Ar, is the aromatic group that remains after the removal of a hydrogen atom from an __. The __, Ph, is the simplest __. The generic __ is the aromatic relative of the generic __, which we symbolize R.
    • arenes
    • aryl group
    • aromatic ring
    • phenyl group 
    • Ph
    • aryl group 
    • aryl group (Ar)
    • alkyl group
  18. __ tend to be mroe symmetrical than similar __, so they pack better into crystals and have higher MPs. Similarly, __ are more symmetrical than the __ and __ isomers, and they pack better into crystals nad have higher MPs. 

    The relative BPs of many __ are related to their dipole moments. 

    Benzene and other aromatic hydrocarbons are slightly denser than the __, but they are still less dense than water. The __ are denser than water. __ and __ are generally insoluble in water, although some derivatives with strongly polar functional groups are moderately soluble in water.
    • benzene derivatives
    • aliphatic compounds
    • para-disubbed benzenes
    • ortho
    • meta
    • benzene derivatives
    • nonaromatic analogues
    • halogenated benzenes
    • aromatic hydrocarbons
    • halogenated aromatics
  19. Aromatic compounds are readily indentifed by their __ because they show a chracteristic C=C stretch around 1600 cm^-1. This is a lower C=C stretching frequency than for isolated alkenes or __ because the aromatic bond order is only about 1.5. The aromatic bond is therefore less __ than a normal double bond, and it vibrates at a lower frequency.
    • infrared spectra
    • conjugated dienes
    • stiff
  20. Like alkenes, __ show unsaturated =C-H stretching just above 3000 cm-1. The combo of the aromatic C=C stretch around 1600 cm-1 and the =C-H stretch just above 3000cm-1 leaves little doubt of the presence of the __.
    • aromatic compounds
    • aromatic ring
  21. Aromatic compounds give readily identifiable __ signals around δ7 to δ8, strongly deshielded by the aromatic ring current. In benzene, the __ absorb around δ7.2. The signals may be moved farther downfield by __ such as carbonyl, nitro, or cyano groups, or upfield by __, such as hydroxyl, alkoxy, or amino groups.
    • 1H NMR s
    • aromatic protons
    • electron-withdrawing groups
    • electron-donating groups
  22. __ that are ortho or meta usually split each other. The __ are about 8 Hz for ortho protons and 2 Hz for meta protons. 

    __ absorb around δ120 to δ150 int eh 13C NMR spectrum. Alkene carbon atoms can also absorb in this spectral region, but the combo of 13C NMR with 1H NMR or IR spectroscopy usually leaves no doubt about the presence of an aromatic ring.
    • nonequivalnet aromatic protons
    • spin-spin splitting constants
    • aromatic carbon atoms
  23. The most common __ of __ is the cleavage of a benzylic bond to give a __.The __ may rearrange to give the aromatic __.__  frequently give ions corresponding to the __ ion at m/z91.
    • mass spectra fragmentation
    • alkylbenzene derivatives
    • resonance-stabilized benzylic cation
    • benzyl cation
    • troplium ion
    • alkylbenzenes
    • tropylium ion
  24. The UV spectra of aromatic compounds are quite different from those of __. For example, benzene has __ absorptions int eh UV region: an __ at λmax=184 nm, a __ at λmax=204, and a chatacteristic __ of multiple absorptions centered around 254 nm.
    • nonaromatic polyenes
    • intense band
    • moderate band
    • low-intensity band
  25. All three major bands in the benzene spectrum correspond to π-->π* transitions. the absorption at 184 nm corresponds to the energy of the transition from one fo teh two ___ to one of teh two __. The weaker band at 204 nm corresponds to a __ that would be impossible to observe if benzene were always an unperturbed, perfectly hexagonal structure.
    • HOMOs
    • LUMOs
    • "forbidden" transition
  26. The most characteristic part of hte spectrum is the band centered at 254 nm, called the __. About three to six small, sharp peaks (called __) usually appear in this band. Their __ are weak, usually 200 to 300. These __ correspond to additional __.
    • benzenoid band
    • fine structure
    • molar absorptivities
    • benzenoid absorptions
    • forbidden transitions
  27. Simple __ show most of the characteristics of __, including the moderate band in the 210-nm region and the benzenoid band in the 260 nm region. __ and __ substituents increase the values of λmax by about 5 nm. An additional __ can increase the value of λmax by about 30 nm.
    • benzene derivatives
    • benzene
    • alkyl and halogen
    • conjugated double bond