Fluoride ion induced 1,4-elimination from o (trimethylsilyl)- methyl benzyl trimethylammonium iodide (7) has been used to generate o-xylylene (1) in solution. o-Xylylene (1) was observed directly in solution by UV-visible spectroscopy. Using stopped-flow UV-visible spectroscopy it was determined that the dimerization of 1 follows second-order kinetics with a rate constant of 9.94 (+OR-) 0.32 x 10('3) L mol('-1) sec('-1) at 25(DEGREES)C in CH(,3)CN. Two ring-alkylated derivatives of 1, 4-t-butyl-1,2-xylylene (28) and 3,4-(1,1,3,3-tetramethyltrimethyl- ene)-1,2-xylylene (29) were generated and observed by UV-visible spectroscopy. The rate constant for the dimerization of 28 was 3.90 (+OR-) 0.15 x 10('3) L mol('-1 )s('-1) at 25(DEGREES)C and that for 29 was 5.59 (+OR-) 0.21 x 10('3) L mol('-1) s('-1) at 25(DEGREES)C. The similar rate constants observed for the dimerization of 1, 28, and 29 led to the conclusion that when undergoing dimerization the o-quinodimethane monomers prefer a non-endo approach;The dimerization kinetics of 5-ethylidene-6-methylene-1,3-cyclohexadiene (9) and 5,6-bis(ethylidene)-1,3-cyclohexadiene (10) were studied by stopped-flow UV-visible spectroscopy. At 25(DEGREES)C in CH(,3)CN k(,9)/k(,1) = 0.59 and k(,10)/k(,1) = 0.016. The dimerization of 9 and 10 led predominantly to one stereoisomer in each case. The similar rate constants for the dimerization of o-xylylene (1) and 9, and the much slower rate constant observed for the dimerization of 10 provided evidence for a stepwise mechanism for the dimerization of benzenoid o-quinomethanes;The fluoride ion induced 1,4-elimination methodology used in the generation of o-xylylene (1) was utilized in the formation and observation of 1,2-napthoquinodimethane (2) and 9,10-phenanthro- quinodimethane (3). o-Quinodimethane (2) was observed in solution by UV-visible spectroscopy while 3 was observed by ('1)H NMR spectroscopy. Both of these species were considerably more stable;than 1, with k(,1)/k(,2) = 163 and k(,1)/k(,3) = 590,000 at 25(DEGREES)C. Both 2 and 3 dimerized following second-order kinetics; *DOE Report IS-T-1294. This work was performed under contract No. W-7405-Eng-82 with the U.S. Department of Energy.
","abstract_html":"<p>Fluoride ion induced 1,4-elimination from o (trimethylsilyl)- methyl benzyl trimethylammonium iodide (7) has been used to generate o-xylylene (1) in solution. o-Xylylene (1) was observed directly in solution by UV-visible spectroscopy. Using stopped-flow UV-visible spectroscopy it was determined that the dimerization of 1 follows second-order kinetics with a rate constant of 9.94 (+OR-) 0.32 x 10('3) L mol('-1) sec('-1) at 25(DEGREES)C in CH(,3)CN. Two ring-alkylated derivatives of 1, 4-t-butyl-1,2-xylylene (28) and 3,4-(1,1,3,3-tetramethyltrimethyl- ene)-1,2-xylylene (29) were generated and observed by UV-visible spectroscopy. The rate constant for the dimerization of 28 was 3.90 (+OR-) 0.15 x 10('3) L mol('-1 )s('-1) at 25(DEGREES)C and that for 29 was 5.59 (+OR-) 0.21 x 10('3) L mol('-1) s('-1) at 25(DEGREES)C. The similar rate constants observed for the dimerization of 1, 28, and 29 led to the conclusion that when undergoing dimerization the o-quinodimethane monomers prefer a non-endo approach;The dimerization kinetics of 5-ethylidene-6-methylene-1,3-cyclohexadiene (9) and 5,6-bis(ethylidene)-1,3-cyclohexadiene (10) were studied by stopped-flow UV-visible spectroscopy. At 25(DEGREES)C in CH(,3)CN k(,9)/k(,1) = 0.59 and k(,10)/k(,1) = 0.016. The dimerization of 9 and 10 led predominantly to one stereoisomer in each case. The similar rate constants for the dimerization of o-xylylene (1) and 9, and the much slower rate constant observed for the dimerization of 10 provided evidence for a stepwise mechanism for the dimerization of benzenoid o-quinomethanes;The fluoride ion induced 1,4-elimination methodology used in the generation of o-xylylene (1) was utilized in the formation and observation of 1,2-napthoquinodimethane (2) and 9,10-phenanthro- quinodimethane (3). o-Quinodimethane (2) was observed in solution by UV-visible spectroscopy while 3 was observed by ('1)H NMR spectroscopy. Both of these species were considerably more stable;than 1, with k(,1)/k(,2) = 163 and k(,1)/k(,3) = 590,000 at 25(DEGREES)C. Both 2 and 3 dimerized following second-order kinetics; *DOE Report IS-T-1294. This work was performed under contract No. W-7405-Eng-82 with the U.S. Department of Energy.</p>","abstract_has_math":false,"creators":["Macias, James"],"institution":null,"degree_name":"Doctor of Philosophy","degree_level":"dissertation","degree_discipline":null,"degree_department":"Department of Chemistry","school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":1987,"date_issued":"1987","date_published":"1987","updated_at":"2026-07-24T02:37:38Z","subjects":[],"languages":["en"],"rights":[],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier.doi","label":"DOI","values":["https://doi.org/10.31274/rtd-180813-11780"],"render_values":[{"text":"https://doi.org/10.31274/rtd-180813-11780","href":"https://doi.org/10.31274/rtd-180813-11780","code":true}]},{"key":"dc:identifier","label":"Identifier","values":["archive/lib.dr.iastate.edu/rtd/8561/"],"render_values":[{"text":"archive/lib.dr.iastate.edu/rtd/8561/","href":null,"code":true}]}]},"links":{"outbound_url":"https://dr.lib.iastate.edu/handle/20.500.12876/81563","outbound_label":"Repository record","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.department","label":"Department","values":["Department of Chemistry"]},{"key":"dc:creator","label":"Author","values":["Macias, James"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2018-08-15T06:59:08.000"]},{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2020-07-02T06:07:42Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2020-07-02T06:07:42Z"]},{"key":"dc:date.issued","label":"Date","values":["1987"]},{"key":"dc:type","label":"Dc Type","values":["dissertation"]},{"key":"thesis:degree_level","label":"Degree Level","values":["dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Doctor of Philosophy"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["archive/lib.dr.iastate.edu/rtd/8561/"]},{"key":"dc:identifier.doi","label":"DOI","values":["https://doi.org/10.31274/rtd-180813-11780"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://dr.lib.iastate.edu/handle/20.500.12876/81563"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Fluoride ion induced 1,4-elimination from o (trimethylsilyl)- methyl benzyl trimethylammonium iodide (7) has been used to generate o-xylylene (1) in solution. o-Xylylene (1) was observed directly in solution by UV-visible spectroscopy. Using stopped-flow UV-visible spectroscopy it was determined that the dimerization of 1 follows second-order kinetics with a rate constant of 9.94 (+OR-) 0.32 x 10('3) L mol('-1) sec('-1) at 25(DEGREES)C in CH(,3)CN. Two ring-alkylated derivatives of 1, 4-t-butyl-1,2-xylylene (28) and 3,4-(1,1,3,3-tetramethyltrimethyl- ene)-1,2-xylylene (29) were generated and observed by UV-visible spectroscopy. The rate constant for the dimerization of 28 was 3.90 (+OR-) 0.15 x 10('3) L mol('-1 )s('-1) at 25(DEGREES)C and that for 29 was 5.59 (+OR-) 0.21 x 10('3) L mol('-1) s('-1) at 25(DEGREES)C. The similar rate constants observed for the dimerization of 1, 28, and 29 led to the conclusion that when undergoing dimerization the o-quinodimethane monomers prefer a non-endo approach;The dimerization kinetics of 5-ethylidene-6-methylene-1,3-cyclohexadiene (9) and 5,6-bis(ethylidene)-1,3-cyclohexadiene (10) were studied by stopped-flow UV-visible spectroscopy. At 25(DEGREES)C in CH(,3)CN k(,9)/k(,1) = 0.59 and k(,10)/k(,1) = 0.016. The dimerization of 9 and 10 led predominantly to one stereoisomer in each case. The similar rate constants for the dimerization of o-xylylene (1) and 9, and the much slower rate constant observed for the dimerization of 10 provided evidence for a stepwise mechanism for the dimerization of benzenoid o-quinomethanes;The fluoride ion induced 1,4-elimination methodology used in the generation of o-xylylene (1) was utilized in the formation and observation of 1,2-napthoquinodimethane (2) and 9,10-phenanthro- quinodimethane (3). o-Quinodimethane (2) was observed in solution by UV-visible spectroscopy while 3 was observed by ('1)H NMR spectroscopy. Both of these species were considerably more stable;than 1, with k(,1)/k(,2) = 163 and k(,1)/k(,3) = 590,000 at 25(DEGREES)C. Both 2 and 3 dimerized following second-order kinetics; *DOE Report IS-T-1294. This work was performed under contract No. W-7405-Eng-82 with the U.S. Department of Energy.
"]},{"key":"dc:format.mimetype","label":"Dc Format Mimetype","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["I. Direct observation of o-xylylene (o-quinodimethane) in solution, Dimerization kinetics of some o-quinodimethanes; II. Kinetic and product studies on the dimerization of [alpha]-methyl-substituted o-quinodimethanes; III. Direct observation of 1,2-napthoquinodimethane and 9,10-phenanthroquinodimethane, Dimerization kinetics of resonance-stabilized o-quinodimethanes"]}]}],"canonical_facts":{"dc:contributor.department":["Department of Chemistry"],"dc:creator":["Macias, James"],"dc:date":["2018-08-15T06:59:08.000"],"dc:date.accessioned":["2020-07-02T06:07:42Z"],"dc:date.available":["2020-07-02T06:07:42Z"],"dc:date.issued":["1987"],"dc:description.abstract":["Fluoride ion induced 1,4-elimination from o (trimethylsilyl)- methyl benzyl trimethylammonium iodide (7) has been used to generate o-xylylene (1) in solution. o-Xylylene (1) was observed directly in solution by UV-visible spectroscopy. Using stopped-flow UV-visible spectroscopy it was determined that the dimerization of 1 follows second-order kinetics with a rate constant of 9.94 (+OR-) 0.32 x 10('3) L mol('-1) sec('-1) at 25(DEGREES)C in CH(,3)CN. Two ring-alkylated derivatives of 1, 4-t-butyl-1,2-xylylene (28) and 3,4-(1,1,3,3-tetramethyltrimethyl- ene)-1,2-xylylene (29) were generated and observed by UV-visible spectroscopy. The rate constant for the dimerization of 28 was 3.90 (+OR-) 0.15 x 10('3) L mol('-1 )s('-1) at 25(DEGREES)C and that for 29 was 5.59 (+OR-) 0.21 x 10('3) L mol('-1) s('-1) at 25(DEGREES)C. The similar rate constants observed for the dimerization of 1, 28, and 29 led to the conclusion that when undergoing dimerization the o-quinodimethane monomers prefer a non-endo approach;The dimerization kinetics of 5-ethylidene-6-methylene-1,3-cyclohexadiene (9) and 5,6-bis(ethylidene)-1,3-cyclohexadiene (10) were studied by stopped-flow UV-visible spectroscopy. At 25(DEGREES)C in CH(,3)CN k(,9)/k(,1) = 0.59 and k(,10)/k(,1) = 0.016. The dimerization of 9 and 10 led predominantly to one stereoisomer in each case. The similar rate constants for the dimerization of o-xylylene (1) and 9, and the much slower rate constant observed for the dimerization of 10 provided evidence for a stepwise mechanism for the dimerization of benzenoid o-quinomethanes;The fluoride ion induced 1,4-elimination methodology used in the generation of o-xylylene (1) was utilized in the formation and observation of 1,2-napthoquinodimethane (2) and 9,10-phenanthro- quinodimethane (3). o-Quinodimethane (2) was observed in solution by UV-visible spectroscopy while 3 was observed by ('1)H NMR spectroscopy. Both of these species were considerably more stable;than 1, with k(,1)/k(,2) = 163 and k(,1)/k(,3) = 590,000 at 25(DEGREES)C. Both 2 and 3 dimerized following second-order kinetics; *DOE Report IS-T-1294. This work was performed under contract No. W-7405-Eng-82 with the U.S. Department of Energy.
"],"dc:format.mimetype":["application/pdf"],"dc:identifier":["archive/lib.dr.iastate.edu/rtd/8561/"],"dc:identifier.doi":["https://doi.org/10.31274/rtd-180813-11780"],"dc:identifier.uri":["https://dr.lib.iastate.edu/handle/20.500.12876/81563"],"dc:language.iso":["en"],"dc:title":["I. Direct observation of o-xylylene (o-quinodimethane) in solution, Dimerization kinetics of some o-quinodimethanes; II. Kinetic and product studies on the dimerization of [alpha]-methyl-substituted o-quinodimethanes; III. Direct observation of 1,2-napthoquinodimethane and 9,10-phenanthroquinodimethane, Dimerization kinetics of resonance-stabilized o-quinodimethanes"],"dc:type":["dissertation"],"thesis:degree_level":["dissertation"],"thesis:degree_name":["Doctor of Philosophy"]},"updated_at":"2026-07-24T02:37:38Z"}