¹H NMR chemical shifts of gaseous amines

Abstract

Gas-phase 200MHz 'H NMR spectra of nineteen primary and nine secondary aliphatic amines were obtained at total densities below 0.15 amagat at 148.6 OC. Theoretical predictions of 'H chemical shifts of ammonia and methylamine are compared with the gas-phase experimental values. The amino proton chemical shifts move downfield with increasing alkyl group size. For series of amines with similar structural geometry about the amino nitrogen, the 'H amino proton chemical shifts correlate reasonably well with gas-phase basicities as measured via ion cyclotron resonance spectroscopy ( r = 0.95 for a linear fit of chemical shift to the gas-phase basicity for the primary amines and r = 0.93 for the secondary amines). Gas-phase 'H NMR spectra for linear diamines, hydroxyamines, cyclic amines and substituted anilines were also obtained.

A GIAO/DFT study of 1H, 13C and 15N shieldings in amines and its relevance in conformational analysis

“…For some of these compounds two conformations have been calculated: ethylamine (3) with the methyl group synclinal (sc, 3a) and antiperiplanar (ap, 3b); piperidine (9) with the NH axial (9a) and equatorial (9b); and 1methylpiperidine (13) with the N-methyl group axial (13a) and equatorial (13b) (note that all six-membered amines are chairs). 2 For compounds 8 and 12 only one minimum was found.…”

Gauge invariant atomic orbital‐density functional theory prediction of accurate gas phase 1H and 13C NMR chemical shifts

“…1 H is one of the important nuclei in chemistry because it has high sensitivity and vast occurrence in organic compounds. Despite this common occurrence, there are few studies on the 1 H NMR chemical shifts of the amino group (33,34). Recently, Alkorta and Elguero (35) calculated 1 H shieldings in amines at the B3LYP/6-311þþG** level of theory, which has been suggested to ''choose the highest reasonable possible level of theory'' for calculations of molecular magnetic properties (36).…”

Molecular Recognition Using Ruthenium(II) Porphyrin Thiol Complexes as Probes

“…1 H NMR: OEP, δ 9.57 (s, 8H, meso-H), 3.88 (q, 16H, 3 J HH = 7.59, CH 2 ), 1.91 (t, 24H, 3 J HH = 7.59, CH 3 ); PhSH, δ 6.34−6.24 (m, 2H, p-Ph), 5.92−5.87 (m, 4H, m-Ph), 4H, 3.52 (s,12H,OCH 3 );BnSH,2H,4H,4H, 6.38 (m,2H,4H,4H,, −0.98 (d, 4H, 3 2H,4H,4H,, −1.02 (d, 4H, 3 J HH = 7.43, CH 2 ), −3.84 (t, 2H, 3 J HH = 7.43, SH). 19 F{ 1 H} NMR: H 4 Cl); n PrSH, δ −0.70 (t, 6H, 3 J HH = 7.18, C 3 H 3 ), −1.27 to −1 H 4 Cl), 7.40 (AA′BB′, 8H, m-C 6 H 4 Cl); n BuSH, δ −0.11 (t, 6H, 3 J HH = 7.38, C 4 H 3 ), −0.35 to −0.42 (m, 4H, C 3 H 2 ), −1.29 to −1.39 (m, 4H, C 2 H 2 ), −2.14 to −2.24 (m, 4H, C 1 H 2 ), −4.20 (t, 2H, 3 J HH = 6 H 4 Cl), 7.43 (AA′BB′, 8H, m-C 6 H 4 Cl); t BuSH, δ −1.56 (s, 18H, C 2 H 3 ), −4.00 (s, 2H…”