¹³C Nuclear Magnetic Resonance Studies. XVI. ¹³C Spectra of some Substituted Acrylic Acids and their Methyl Esters. A Correlation of Olefinic Shieldings in α,β-unsaturated Carbonyl Systems

Abstract

The carbon-13 n.m.r. spectra of 26 a$-unsaturated methyl esters and 16 substituted acrylic acids have been determined and the I3C shieldings are discussed. These data are compared with the recently reported values for several a$-unsaturated carboxylic acids. Linear regression analysis of the olefinic shielding data for several a$-unsaturated carbonyl derivatives yields a set of parameters which correlate the results with reasonable precision. The solvent dependence of the 13C shieldings of acrylic acid and methyl acrylate has been examined briefly. The proton results for the methyl esters are discussed briefly.Les spectres r.m.n. du carbone 13 de 26 mtthyl esters a$-insaturts et de 16 acides acryliques substituts ont t t t dttermints et les effets d'tcran I3C sont discutts. Ces donntes sont compartes aux valeurs recemment rapporttes pour quelques acides carboxyliques a,p-insaturts. Une analyse de la regression lineaire des donntes de l'effet d'ecran olefinique pour quelques dtrivts carbonylts a$-insaturts permet d'obtenir une strie de parametres qui sont en corrtlation, avec une prtcision raisonnable avec les rtsultats. La dtpendance entre le solvant et les effets d'ecran de I3C pour I'acide acrylique et I'acrylate de mtthyle a t t t examinte brievement. Les rtsultats concernant les protons pour les esters mtthylts sont discutts brievement.

Odor Thresholds of Various Unsaturated Branched Esters

“…The angelates and tiglates were readily distinguished on the basis of their mass spectra (3). C NMR values found for ethyl 2-methyl-2-butenoate and ethyl 3-methyl-2-butenoate were in good agreement with those reported for the corresponding methyl esters (4). Ethyl (E)-2-methyl-2-hexenoate had very similar 13 C NMR values to those reported for the corresponding methyl ester (5).…”

13C Nuclear Magnetic Resonance Studies. XX. 13C Shieldings of Several Allyl Alcohols. Geometric Dependence of 13C Shieldings

“…spectra of several unsaturated aliphatic systems were discussed and the results of an examination of a$-unsaturated carboxylic acids and esters compared with earlier data (1). These results clearly showed that olefinic 13C shieldings exhibit a marked dependence on the orientation of substituents bonded to the olefinic carbons.…”

“…(23) whereas their fin-effects are shielding ( Table 5). The parameters in Table 5 may be compared with a similar set generated for a$-unsaturated carboxylic acids and esters (1) to assess the effect of conjugation on the sensitivity of the olefinic shieldCan. J. Chem.…”

The Vinylketene‐Acylallene Rearrangement: Theory and Experiment

“…74 (42), 59 (231, 56 (36), 43 (loo), 42 (51), 41 (9),40 (7), 39 (21). (9), 113 (27), 101 (38),85(73),84 (28),69(57), 59(17),43(100).42(15),41 (13), 40 (9j, 39 (26). The ('H and ''C) NMR ('24) 15.2 (CH,CH,).…”