Flashcards
ch 18
Flashcards do conjunto (85)
- 1what is the major product for the nitration of toluene? draw itortho
- 2what is the major product for the nitration of anisole? draw itpara
- 3what is the major product for the nitration of nitrobenzene? draw itmeta
- 4what are the major products for nitration of halogens?ortho/para positions
- 5what is an activating group?groups that cause the benzene ring to activate
- 6how does an activating group work?donates the electron density to the ring, which stabilizes the positively charged sigma complex and lowers activation energy.
- 7what positions do activating groups direct to?ortho/para directors
- 8what nitrations consist of activating groups?nitration of toluene and anisole,
- 9what is a deactivating group?it deactivates the aromatic ring toward electrophilic aromatic substitution
- 10how does a deactivating group work?it withdrawals electron density from the ring, so the sigma complex is destabilized and raises the activation energy
- 11what positions do deactivators tend to direct to?meta
- 12activating groups tend to be ______ directors and deactivating groups tend to be ______ directors.ortho/para, meta
- 13if halogens are deactivators, why do the ortho/para positions dominate?induction, rather than resonance, becomes the dominant factor, which suggests that the halogens are electron withdrawing. however, the ortho and para positions lead to an additional resonance structure, making them more stable than the meta position.
- 14draw all the strong activators
- 15draw all the moderate activators
- 16draw all the weak activators
- 17draw all the strong deactivators
- 18draw all moderate deactivators
- 19draw all weak deactivators
- 20What is the final product when Br2 is reacted with benzene?there is no reaction
- 21what is needed to make Br2 react with benzene?Fe (iron)
- 22what is the final product when benzene is reacted to Br2 and Fe?1-bromobenzene (a single br substituent)
- 23what is an electrophilic aromatic substitution reactionwhen the aromatic protons are replaced by an electrophile and the aromatic ring is preserved
- 24during bromination of benzene, what does Br2 function as?it functions as an electrophile
- 25what is the purpose of iron during bromination of benzene?it enhances the electrophilicity of the bromine atom that is acting as an electrophile
- 26Draw the mechanism for Br2 interacting with ironsee mechanism on pg 792
- 27what does the aromatic ring function as?the nucleophile
- 28what is the intermediate of this reaction called?sigma complex / arenium ion
- 29is the sigma complex resonance stabilized?yes
- 30is the sigma complex aromatic?it loses aromaticity during formation of sigma complex, but it does become aromatic when the sigma complex is deprotonated.
- 31what reagents can be used to brominate benzene?- Fe (iron tribromide)
- AlBr3 (aluminum tribromide) - 32what process is this substitution reaction?exergonic - a downhill process and thermodynamically favorable
- 33what reagents are used for chlorination of benzene?- AlCl3 (aluminum trichloride)
- 34Draw the mechanism for bromination of benzenesee 792
- 35Draw mechanism for chlorination of benzenesee 793
- 36Draw mechanism for formation of aluminum trichloridesee 793
- 37what products are leftover for bromination of benzene? what about chlorination?- FeBr3, HBR
- AlCl3, HCl - 38what are the first steps of bromination and chlorination? what about the second?- nucleophilic attack
- proton transfer - 39why is fluorination of benzene not seen?it is a violent process and difficult to control
- 40why is iodination of benzene not seen?it is often slow with poor yields
- 41what reagents are needed for sulfonation of benzene?fuming H2SO4
- 42what is the resulting product of sulfonation?benzene-sulfonic acid
- 43what is fuming sulfuric acid a mix of?H2SO4 and SO3 gas
- 44what is sulfur trioxide (SO3)?a powerful electrophile
- 45Draw the mechanism of sulfonationpg 795
- 46Draw the resulting product of sulfonation of benzenesee 795
- 47why is sulfonation process reversible?the reaction between benzene SO3 is highly sensitive to concentrations of reagents
- 48what reagents are used to reverse sulfonation?dilute H2SO4
- 49what reagents are used to nitrate benzene?HNO3 / H2SO4
- 50what is the final product of nitration of benzene? draw itnitrobenzene, see pg 797
- 51during nitration, what molecule is the electrophile?nitronium ion (NO2+)
- 52what kind of reaction takes place to form the nitronium ion?an acid/base reaction that takes place between HNO3 and H2SO4
- 53draw the reaction of the formation of nitronium ionsee pg 798
- 54what reagents can reduce a nitro group on a benzene to an amino group?- Fe, HCl / NaOH or
- Zn, HCL ? NaOH - 55how do you install an amino group on a benzene?1) HNO3 / H2SO4
2) Fe or Zn, HCL
3) NaOH - 56how is an alkyl group installed on a benzene ring?- Friedel-Crafts alkylation
- 57what does a Friedel Crafts alkylation consist of?- an alkyl halide reacting with a Lewis acid
- 58what forms in a Friedel Crafts alkylation?- carbocation
- 59Draw the mechanism for carbocation information, as well as Friedel crafts alkylationpg 800
- 60what alkyl halides work best with Friedel crafts alkylation? Which ones do not?- secondary and tertiary are readily converted by AlCl3
- primary alkyl halides are too high in energy - 61what primary halide does undergo Friedel-Crafts alkylation?- ethyl chloride (and AlCl3)
- 62what happens when primary alkyl halides are used in Friedel crafts?mixture of products is unavoidable
- 63Fridel Crafts is only efficient when substrate cannot undergo _____rearrangements
- 64the alkyl halides used in Fridel Crafts alkylation must be attached to a ______ hybridized carbon atomsp3
- 65Fridel Crafts alkylation often leads to polyalklylation, what is a solution?choosing reaction conditions that favor monoalykylation
- 66what group does not undergo Friedel crafts alkylation?nitro group
- 67how does an alcyl group get installed on the benzene ring?Friedel crafts acylation
- 68draw the mechanism of the formation of acylium ionpg 802
- 69what reagants are involved in the making of the acylium ion?when acyl chloride is treated with a Lewis acid
- 70are acylium ions resonance stabilized?yes
- 71draw the mechanism for acylationsee pg 803
- 72what is the product of Friedel crafts acylation?aryl ketone
- 73how can an aryl ketone be reduced?using a clemmenson reduction
- 74what are the reagents needed in a clemmensen reduction?Zn (Hg) / HCl, heat
- 75is polyalcylation observed?no
- 76during nitrations of benzene rings that already contain a substituent, what happens if there is competition between resonance and induction effects?resonance is the dominant factor
- 77when a benzene ring with an anisole substituent is treated with xs Br2 and NO Lewis acid, what is the product?- all three positions undergo bromination (two orthodo and one para, no meta)
- 78for activating groups that donate electron density, what charge does that put on the sigma complex?negative
- 79for deactivating groups that donate electron density, what charge does that put on the sigma complex?positive
- 80how are halogens deactivators, yet ortho/para directors?they are electron withdrawing, but they cause the sigma complex to be positively charged
- 81which is more dominant, ortho or para?para
- 82when are steric effects especially important?- between ortho and para
- between 1,4 and 1,3 disubstituted positions - 83what is a blocking group?it is a group that can be used to obtain the desired product, when a different product would have dominated
- 84what reagents are useful for creating a blocking group?- fuming H2SO4 (leads to installation of sulfonation)
- bromination (goes to position leftover)
- dilute H2SO4 (gets rid of sulfonation group) - 85—
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- Chemistry FlashCards sobre ch 18, criado por Tessa Watson em 08-04-2021.
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- Tessa Watson
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