The microwave spectrum and structure of allyl alcohol

The microwave spectrum of the normal species of the gauche, gauche isomer of allyl alcohol has been reassigned and rotational and centrifugal distortion constants have been determined. Rotational constants of nine deuterated species three carbon-13 species and the oxygen-18 species have also been obtained. These data were used to estimate structural parameters by least-squares fitting of the effective moments of inertia. Good agreement with an earlier electron diffraction and ab initio study was obtained. Unassigned transitions from another isomer were observed, presumably the cis, gauche conformer.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26503/1/0000039.pd

Spectroscopy of 1,4,4-trifluorocyclobutene

A new compound, 1,4,4-trifluorocyclobutene (144FCB), has been obtained as a byproduct in the reduction of perfluorocyclobutene with sodium borohydride. A comprehensive spectroscopic study of 144FCB has been undertaken including microwave, IR, Raman and NMR data. Ground state rotational constants, A=3629.34, B=2600.74, and C=2098.93 MHz, were derived from the microwave data and used to distinguish 144FCB from other possible isomers and to propose a structure. NMR chemical shifts and coupling constants and the vibrational fundamentals are assigned and compared to other members of the cyclobutene family. Frequencies of vibrational fundamentals of 144FCB (cm-1) are: (a') 3126, 2967, 1679, 1457, 1377, 1245, 1179, 1045, 914, 752, 690, 577, 453, 263, 213; (a") 3000, 1198, 1061, 938, 821, 577, 381, 190, -. A small amount of 3,3,4-trifluorocyclobutene has also been found in the products of the reduction reaction, and its NMR spectra and its IR spectrum are reported.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28527/1/0000324.pd

Interrelationship between carboxy(vinyl)ketenes, methyleneketenes, vinylketenes, and hydroxyacetylenes

Carboxy(vinyl)ketenes, alkylideneketenes, and vinylketenes have been obtained selectively, sequentially, and isomerically pure for the first time by flash vacuum pyrolysis of 2,2-dimethyl-5-alkylidene-1,3-dioxane-4,6-diones (Meldrum's acid derivatives) under controlled conditions. Each of the ketenes was directly observed by IR spectroscopy and trapped with methanol or aniline. Highly unstable compounds believed to be the hydroxyacetylene isomers of the alkylidene- and vinylketenes have been observed for the first time

MICROWAVE SPECTRUM AND STRUCTURE OF CYCLOBUTADIENE OZONIDE

Author Institution: Department of Chemistry, University of MichiganSix isotopic species of cyclobutadiene ozonide (2,3,7-trioxabicyclo(2.2.1) hept-5-ene) containing D. $^{18}O$ and $^{13}C$ enrichment were prepared by singlet oxygen addition to furan. Rotational and centrifugal distortion constants were determined for all six species and were sufficient to determine the complete structure of the molecule. Perhaps the most interesting structural feature is the non-planarity about the C=C bond, where the hydrogen atoms are bent $8.9^{\circ}$ towards the endo side

MECHANISM OF FRAGMENTATION OF ALKYLIDENE-MELDRUMS ACIDS - CARBOXYKETENE, VINYLKETENE, AND METHYLENEKETENE INTERMEDIATES FROM 5-CYCLOPENTYLIDENE-2,2-DIMETHYL-1,3-DIOXANE-4,6-DIONE

Three ketenes were successively observed on flash vacuum pyrolysis of 5-cyclopentylidene-2,2-dimethyl-1,3-dioxane-4,6-dione (5), viz., carboxycyclopentenylketene (11, 2126 cm), cyclopentylideneketene (12, 2087 cm), and cyclopentenylketene (13, 2110 cm). 11 was thermally converted to 13 and probably also to 12. 12 itself rearranged thermally to 13. The three ketenes were trapped with methanol to give the esters 14, 15, and 16. 14 was thermally unstable, rearranging at room temperature to methyl cyclopentylidenemalonate (14a) and decarboxylating at 150 °C, predominantly to 16. A dimer of 12, 2,4-bis(cyclopentylidene)cyclobutane-1,3-dione (17), was also isolated. 1-Cyclopentenyldiazomethane (18) was prepared and pyrolyzed to 1,3-cyclohexadiene and benzene. No evidence for the formation of cyclohexyne (17) was obtained in any of these experiments