bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of biosynthetic 13C enrichment using [1,2‐13C2] acetate as precursor for 13C NMR spectral assignment of the isopropyl methyls of (24β)‐ethylsterols
Authors: Nicotra Francesco , Ronchetti Fiamma , Russo Giovanni , Toma Lucio , Ranzi Bianca M. 
Published: May 2005

AbstractThe resonances of C‐26 and C‐27 in the 13C NMR spectra of two (24β)‐ethylsterols, poriferasterol and clionasterol, were unambiguously assigned through a biosynthetic experiment from [1,2‐13C2]acetate in the chrysophyte Ochromonas malhamensis; the conclusion that the hydride migration from C‐24 to C‐25 during the biosynthesis of phytosterols occurs in most cases on the si‐face of the 24‐double bond precursor is experimentally established.
Carbon‐13 NMR spectra of dispiro compounds: Effect of homologation on chemical shifts of spiro carbons
Authors: Seth Neelima M. , Bhaduri A. P. 
Published: May 2005

AbstractA comparative study of the 13C NMR spectra of derivatives of 14‐alkoxy‐ and 14‐hydroxy‐14‐azadispiro[5.1.5.2]pentadec‐9‐ene‐7,15‐diones and 12‐alkoxy‐and 12‐hydroxy‐12‐azadispiro[4.1.4.2]tridec‐8‐ene‐6,13‐diones has been carried out to establish the effect of homologation on the chemical shift of the twospiro carbons in the former class of compounds. Of the two spiro carbons of the derivatives of 14‐alkoxy‐14‐azadispiro[5.1.5.2]pentadec ‐ 9 ‐ ene ‐ 7, 15 ‐diones C‐8 was found to have experienced a greater shielding effect on homologation than the spiro carbon C‐6.
14N NQR study of the effect of protonation on the charge distribution of some N‐methylated ureas
Authors: Murgich Juan , Santana R. Magaly , Abanero José 
Published: May 2005

AbstractThe 14N NQR frequencies measured at 77 K for the amine group of the 1:1 salts of nitric acid with methylurea and 1,3‐ and 1,1‐dimethylurea and the phosphoric acid salt of 1,3‐dimethylurea are reported. The analysis of the NQR data showed that the N loses population from its π orbital. The decrease in π population is partially compensated by an increase in the population of the NC σ bonds. The loss of π population is enhanced when the H atoms of the amine group are substituted by electron‐donating groups such as CH3.
Analysis of internal rotations and rotational diffusion of N,N‐dimethyl‐1‐pyrenecarboxamide in CDCL3 solution
Authors: Gryff‐Keller A. , Poppe L. 
Published: May 2005

AbstractThe equilibrium conformation of N,N‐dimethyl‐1‐pyrenecarboxamide in CDCl3 solution has been deduced and the internal rotation rates around all single bonds, as well as the overall reorientation, have been characterized using dynamic NMR and 1H, 13C and 14N relaxation measurements.
1H nuclear magnetic resonance of α‐hexahydro‐1,3,5‐trinitro‐s‐triazine (RDX) and the α‐, β‐, γ‐ and δ‐polymorphs of octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine (HMX)
Authors: Landers A. G. , Apple T. M. , Dybowski Cecil , Brill T. B. 
Published: May 2005

Abstract1H NMR spectra of the energetic materials α‐hexahydro‐1,3,5‐trinitro‐s‐triazine (RDX) and the α‐, β‐, γ‐ and δ‐polymorphs of octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine (HMX) have been obtained in the solid phase. Primary and secondary dipole‐dipole interactions can be observed, which allows calculation of the intramolecular H …︁ H distances. The spectra suggest that γ‐HMX, the molecular structure of which is unknown, possesses a chair‐chair ring conformation similar to that of α‐ and δ‐HMX.
Assignment of quaternary carbons via two‐bond heteronuclear selective NOE difference, a useful structure elucidation aid
Authors: Sánchez‐Ferrando Francisco 
Published: May 2005

AbstractVery low power irradiation of suitable narrow peaks in the proton frequency range generated NOE enhancement in neighbouring quaternary carbons, positioned two bonds from the irradiated protons. Subsequent FID acquisition under normal broad band decoupling yielded the NOE‐containing FID, which, after subtraction of the unperturbed broad band decoupled FID (devoid of NOE), gave the final NOE difference FID to which only the carbons undergoing NOE enhancement had contributed. Fourier transformation of the latter gave the NOE difference spectrum, usually a one‐ or two‐peak spectrum. This technique proved particularly useful for polysubstituted aromatic rings.
Carbon‐13 and platinum‐195 spin‐lattice relaxation times of tetrabutylammonium pyridinetrichloroplatinate(II)
Authors: Lystbaek K. , Bildsøe H. 
Published: May 2005

Abstract13C and 195Pt spin‐lattice relaxation times, T1, have been determined for tetra‐n‐butylammonium trichloro‐pyridineplatinate(II) in different solvents. Correlation times for internal rotation around the PtN bond and for the overall motion are calculated based on a two‐site random jump model for the internal rotation. The results indicate that the ion pair forms molecular aggregates or stacks in low dielectric solvents. 13C Ti values for tetra‐n‐butylammonium trichloro(2‐propylpyridine)platinate(II) indicate that internal rotation around the PtN bond also takes place in this compound.
Carbon‐13 and hydrogen NMR data for a series of 1,4‐benzodiazepines
Authors: Scahill Terrence A. , Smith Stanford L. 
Published: May 2005

AbstractHydrogen and carbon chemical shifts and H‐H and C‐H couplings are reported for five simple 1,4‐benzodiazepines, three imidazolo‐1,4‐benzodiazepines, two modified triazolo‐1,4‐benzodiazepines.
Unusual 13C/77se couplings in the 13C NMR spectra of selenoimidates
Authors: Meese Claus O. , Walter Wolfgang 
Published: May 2005

AbstractThe 13C NMR. chemical shifts of several selenoimidates (3) are reported in comparison with imidates (1) and thioimidates (2). Distinct resonance signals of 3 show additional satellites arising from 77Se couplings. Extremely large three‐bond couplings [3J(13C77Se) = 28–39 Hz] are observed in the Z configuration of the N‐methylselenoimidate double bond, where the coupling nuclei (77SeCN13C) are cis‐orientated.
1H NMR spectra of various methylangelicins
Authors: Manzini Paolo , Rodighero Paolo , Pastorini Giovanni , Guiotto Adriano 
Published: May 2005

AbstractA full analysis of the 1H NMR spectra of angelicin (2H‐furo[2,3‐h]‐l‐benzopyran‐2‐one) and of 25 of its mono‐, di‐ and tri‐methyl analogues, allows the assignments of all the peaks in the spectra to be made with reasonable certainty. Coupling constants have also been utilized in order to provide a better fit of the data.
Nitrogen‐15 NMR study of some barbituric acid derivatives
Authors: Nieminen Antti O. K. , Rautio Marjatta , Rahkamaa Erkki 
Published: May 2005

AbstractThe 15N chemical shifts and the one‐, two‐ and three‐bond 15N‐1H spin‐spin coupling constants for ten unenriched barbituric acid derivatives have been measured at 10.14 MHz in dimethyl sulphoxide‐d6. The measured 15N chemical shifts are in three distinct ranges: −270 to −280 ppm for urea‐type nitrogens, approximately −264 ppm for amide‐type nitrogens and between −226 and −236 ppm for imide‐type nitrogens, in accord with the gradually increasing possibility for delocalization of the nitrogen lone‐pair electrons. The 2 ppm shielding effect of the side‐chain hydroxy group, together with the 5 ppm shielding effect of the N‐methylation on the ring nitrogens, allows the identification of the diastereoisomers of 5‐allyl‐5‐(2‐hydroxypropyl)‐1‐methyl‐2,4,6(1H,3H,5H)‐pyrimidinetrione. The three‐bond coupling constant of 1.5 ± 0.2 Hz found in five compounds is a unique example of pure trans‐type spin‐spin coupling over an NCONH path. This study shows that particular attention must be paid to sample preparation and measuring conditions in order to achieve structurally significant nitrogen chemical shift and coupling information.
Interpretation of polar aromatic solvent‐induced shifts by means of the multipole approximation model
Authors: Nikki Kunio , Nakagawa Naoya 
Published: May 2005

AbstractThe aromatic solvent‐induced shifts (ASIS) of various polar solutes induced by polar and non‐polar aromatic solvents were determined. The protons that produce a large ASIS in non‐polar solvents show a remarkable depression of the ASIS in highly polar aromatic solvents. The observed ASIS in polar aromatic solvents are in good agreement with the calculated ASIS based on the electrostatic interaction between solute and solvent molecules.
Mechanism of epimerization of 2,3‐erythro‐aldoses to 2,3‐threo‐Aldoses: An NMR study
Authors: Lee Albert W. M. 
Published: May 2005

AbstractProton NMR spectroscopic studies on the conversion of 2,3‐erythro‐aldoses to 2,3‐threo‐aldoses in methanolic K2CO3 solution revealed the formation of the hemiacetals of the corresponding aldehydes, which probably provided the driving force of the easy epimerization.
13C1H Coupling Constants in Fluoropyridines
Authors: Yu. Denisov A. , Mamatyuk V. I. , Shkurko O. P. 
Published: May 2005

AbstractThe proton‐coupled 13C NMR spectra of 2‐, 3‐ and 4‐fluoropyridines were completely analysed and the signs and magnitudes of the 13C‐1H coupling constants determined. The root mean square deviations of the observed J(CH) values from those calculated using empirical correlations between the coupling constants in monosubstituted pyridines and benzenes were found to be 0.90 Hz for 1J(CH) and less than 0.26 Hz for the other nJ(CH) couplings.
NMR study of sesquiterpenes of the helenalin and parthenin series
Authors: Díaz E. , Domínguez G. G. , Mannino A. , Negrón G. , Jankowski K. 
Published: May 2005

AbstractThe assignment of the proton and carbon spectra of some cyclopropane sesquiterpene lactone derivatives of helenalin and anhydroparthenin is presented. The interpretation of the spectra was achieved using 1H‐13C two‐dimensional heteronuclear chemical shift correlation, proton two‐dimensional homonuclear correlated 2D and 2D‐J, and some classical techniques. In particular, the spectra of halocyclopropane derivatives are discussed and compared with the spectra of the parent sesquiterpenes.
Proton magnetic resonance studies of substituted 3,5‐dimethylbenzenes: Influence of substituents on the methyl proton chemical shifts
Authors: Kamounah Fadhil S. , Al‐Sheibani Ikbal. S. , Shibaldain Nazar L. , Salman Salman R. 
Published: May 2005

AbstractProton NMR data for a number of 1‐X‐4‐Y‐3,5‐dimethylbenzenes and 1‐X‐2‐Y‐4‐Z‐3,5‐dimethylbenzenes are presented. The proton chemical shifts of the methyl groups at positions 3 and 5 are mainly affected by the ring current effect of the substituents. This conclusion was strongly supported by the proton chemical shifts calculated using additivity rules.
One‐ and two‐dimensional nuclear overhauser effect. Investigation of the stereochemistry of 5‐functionalized 2‐imidazolines
Authors: Marsura A. , Luu‐Duc C. , Nardin R. 
Published: May 2005

AbstractThe study of 5‐functionalized 2‐imidazolines by 1H NMR, 1‐D NOE and 2‐D NOE is reported. The application of these methods confirms the relative configurations and conformations of the compounds. In particular, NOE effects and related crystallographic data are in good agreement with the proposed angular geometry of the N‐1 and the ring. Some examples of spectra obtained with the different techniques are presented and discussed.
1H Assignments of glycopeptide antibiotics by double quantum NMR and relayed correlation spectroscopy
Authors: Fesik Stephen W. , Perun Thomas J. , Thomas Alford M. 
Published: May 2005

AbstractTwo‐dimensional double quantum NMR and relayed correlation spectroscopy were used to complete the 1H assignments of a series of glycopeptide antibiotics. The double quantum NMR experiments were particularly useful in assigning the complicated aromatic region of the spectra by identifying the coupled protons with small differences in chemical shifts, and simplifying the contour maps by selectively enhancing the cross‐peaks corresponding to either the ortho‐(J≈8 Hz) or meta‐(J≈2 Hz) coupled protons. In addition, from the double quantum NMR experiments, protons belonging to the same spin system were unambiguously identified, even though not directly coupled. The connectivities between remote nuclei belonging to the same network were also established through relayed correlation spectroscopy.
Investigation of the amide rotation in N,N‐dialkylbenzamides. 7–Re‐examination of the role of the hydrogen bond in 2‐mercapto substituted derivatives
Authors: Gryff‐Keller Adam , Szczeciński Przemysław 
Published: May 2005

AbstractBarriers to the amide rotation in 2‐mercapto‐N,N‐dialkylbenzamides [alkyl = CH3 or CH(CH3)2] and some of their derivatives were measured by dynamic 1H NMR. For N,N‐diisopropylamides, barriers to rotation about the carbonyl–aryl bond were also determined. The results show that the intramolecular hydrogen bond has only a very small influence on the measured barriers. In contrast to the literature data, only one set of signals, common to all possible forms of 2‐mercapto‐N,N‐dimethylbenzamide, has been observed.
Complete Assignments of the 13C NMR Spectra of Bilirubin‐IXα and its Dimethyl Ester
Authors: Müller Norbert 
Published: May 2005

AbstractUsing two‐dimensional heteronuclear 1H‐13C chemical shift correlation spectroscopy via one‐bond and long‐range couplings, all 13C resonances of bilirubin‐IXα and its dimethyl ester in dimethyl sulphoxide solution are assigned, independently from reference to partial structures. Previous ambiguities in the methyl regions of the 1H NMR spectra of these compounds are also resolved.
Asymmetry parameters of the electric field gradient at the 35Cl nuclei in compounds of the XC6H4CH2Cl series (X = CH3, Cl)
Authors: Feshin V. P. , Dolgushin G. V. , Voronkov M. G. , Sapozhnikov Yu. E. , Jasman Ya. B. , Popova E. P. 
Published: May 2005

AbstractThe asymmetry parameters of the electric field gradient at the 35Cl nuclei in polycrystalline compounds of the 2‐, 3‐ and 4‐XC6H4CH2Cl (X = CH3, Cl) series were measured at 77 K. The data obtained directly indicate the almost axial symmetry of the electric field gradient at the 35Cl nuclei, and the participation of the pσ electrons of the chlorine atom of the CICH2 group in the interaction with the geminal sp2 carbon atom in the molecules studied.The experimental η values allow a more precise assignment of the lines in the NQR spectrum of 3‐ClC6H4CH2Cl.
Application of two‐dimensional correlated NMR techniques to the structure elucidation of 1‐methoxy‐endo‐tetracyclo[6.3.0.02,11.03,7]‐ undec‐9‐ene
Authors: Kruk C. , Jans A. W. H. , Cornelisse J. , Lugtenburg J. 
Published: May 2005

AbstractBy means of 500 MHz 1H two‐dimensional correlated NMR spectroscopy and the 62.89 MHz 13C two‐dimensional Inadequate technique, all proton and carbon chemical shifts of 1‐methoxy‐endo‐tetracy‐clo[6.3.0.02,11.03,7]undec‐9‐eene can be assigned in an unambiguous way.
Fractional populations of individual conformers in multidihedral systems: A J coupling constant approach
Authors: Barone Vincenzo , Lelj Francesco , Abbate Giancarlo 
Published: May 2005

AbstractThe use of J coupling constants in determining the conformational states of flexible molecules is analysed. A general model is developed which allows a complete specification of the molecular conformation, taking into the proper account the coupling between different dihedral angles. The number of joined fractional populations to be determined increases dramatically with the number of coupled dihedral angles, but it can be substantially reduced by a reasonable partitioning of the potential. An illustrative example is fully developed to show that a simple analysis of forbidden sequences of staggered conformations allows a reliable solution in the case of two coupled internal rotations.
Carbon‐13 chemical shift assignment of some organophosphorus compounds. IV—2‐oxo‐ and 2‐thio‐2‐phenoxy‐1,3,2‐diazaphosphorinanes and related P(IV) compounds
Authors: Al‐Rawi Jasim M. A. , Behnam George Q. , Ayed Naceur , Kraemer R. 
Published: May 2005

AbstractCarbon‐13 chemical shifts and J(POC) and J(PNC) values have been determined for a series of substituted 2‐oxo‐ and 2‐thio‐2‐phenoxy‐1,3,2‐diazaphosphorinanes and related P(IV) compounds. 31P and 1H NMR were used in conjunction with 13C NMR spectra to establish some aspects of the stereochemistry of these compounds. 3J(PNCC) and 3J(POCC) seem to be more sensitive to the stereostructure than the 13C chemical shifts.
Enantiomeric purity of chiral metal carbonyl complexes using Eu(hfc)3
Authors: Solladié‐Cavallo A. , Suffert J. 
Published: May 2005

AbstractIt is shown that the enantiomeric purity of metal carbonyl complexes bearing an aldehyde group can be determined using Eu(hfc)3 and 200 MHz 1H NMR spectroscopy. A correlation between the chemical shifts and the absolute configuration is proposed in the case of the chromium tricarbonyl complexes.
13C NMR spectra of aryl‐substituted spirocyclopropanes
Authors: Abdel‐Wahab A. , Doss S. H. , Dürr H. , Spang P. 
Published: May 2005

AbstractThe 13C NMR spectra of 2‐arylspiro[cyclopropane‐1,9′‐thioxanthene S,S‐dioxides], 1–5, and 2′‐aryl‐spiro[10,11‐dihydro‐5H‐dibenzo[a,d]cycloheptene‐5,1′‐cycyclopropanes], 6–9, are described, and the effects of substituents are discussed. The relationship between the 13C shifts and the Hammett σ constants of substituents on the phenyl ring is not linear for 1–5. For 6–9 the chemical shifts of the cyclopropane carbons (C‐2′ and C‐3′) correlate reasonably well with electron density.
Stereochemical studies of tetracycline antibiotics and their common impurities by 400 MHz 1H NMR spectroscopy
Authors: Casy A. F. , Yasin Ahmed 
Published: May 2005

AbstractThe 400 MHz 1H NMR spectra of hydrochlorides of tetracycline, chlortetracycline, doxycycline and two epimeric derivatives are reported and interpreted in terms of solute conformation in DMSO‐d6 and configuration. Coupling constant magnitudes within the system H‐5, H‐4a, H‐4 and H‐12a and dimethylamino chemical shifts are applied to the configurational assignment of isomeric α‐ and β‐apooxytetracyclines.
13C NMR spectra of 2‐amino‐4H‐pyran derivatives
Authors: Pascual Conrado , Martin Nazario , Seoane Carlos 
Published: May 2005

AbstractThe 13C NMR spectra of sixteen 2‐amino‐4H‐pyran derivatives, consisting of seven 3‐cyano, two 5‐cyano and seven 3,5‐dicyano derivatives, are reported. For the purposes of comparison, 13C NMR data for 2,6‐dimethyl‐3,5‐dicyano‐4‐phenyl‐4H‐pyran are also given.
13C nuclear magnetic resonance spectra of bridged‐ring steroids and related compounds
Authors: Winnik Françoise M. , Yates Peter 
Published: May 2005

AbstractAssignments of the 13C NMR signals of a series of bridged‐ring steroids incorporating a bicyclo [2.2.1] heptane system into ring A or B have been made on the basis of comparisons of their spectra with those of related unbridged steroids and bicyclo[2.2.1] heptane derivatives.
13C NMR spectra of some mesoionic 1,2,3‐triazoles
Authors: Tsoleridis C. A. , Alexandrou N. E. 
Published: May 2005

AbstractThe 13C NMR spectra of three mesoionic 1,2,3‐triazol‐4‐ylacetamides and two 1,2,3‐triazol‐4‐ones were determined, and an evaluation of the shifts in relation to their mesoionic structure was made. A linear correlation between the 13C resonances and net charge densities, calculated by the CNDO/2 method, was obtained.
Carbon‐13 NMR of some organophosphorus compounds. 5‐2‐oxo‐ or 2‐thio‐2‐, 3‐, 4‐, 5‐, or 6‐substituted 1,3,2‐oxazaphosphorinanes and related P(IV) compounds
Authors: Al‐Rawi Jassim M. A. , Ayed Naceur , Kraemer Raymond , Navech Jacques 
Published: May 2005

AbstractThe 13C chemical shifts and PC coupling constants of nine 2‐oxo‐ or 2‐thio‐2‐, 3‐, 4‐, 5‐ or 6‐substituted 1,3,2‐oxazaphosphorinanes, with various groups attached to the ring carbon phosphorus and nitrogen atoms have been analysed. Some aspects of the stereochemistry of these compounds are verified.
31P chemical shifts and 31P—−13C coupling effects in the stereochemical analysis of benzo‐7‐phosphanorbornene derivatives
Authors: Quin Louis D. , Bernhardt F. Christian 
Published: May 2005

AbstractThe first phosphines based on the benzo‐7‐phosphanorbornene system have been prepared and found to have extremely deshielded 31P nuclei. The phosphine with a P‐tert‐butyl group gives the most downfield value (δ +152.5) ever recorded for a tertiary phosphine. The lone‐pair orientation in phosphines controls the magnitude of 2J (PC) and 3J (PC), and these effects were used to determine stereochemical features of the phosphines. These compounds were formed by HSiCl3pyridine reduction of the Diels—Alder adducts of isophosphindole oxides with norbornadiene. 13C NMR was also used to confirm the assignment of these phosphine oxides.
High‐field orientation effects in the high‐resolution proton NMR spectra of diverse porphyrins
Authors: Bothner‐By A. A. , Gayathri C. , van Zijl P. C. M. , MacLean C. , Lai Jan‐Ji , Smith Kevin M. 
Published: May 2005

AbstractDipolar splittings with a quadratic dependence on static magnetic field strength are reported for selected pairs of nuclei in several porphyrins. These splittings are detectable as a result of a slight molecular alignment caused by the interaction of the static magnetic field with the anisotropic magnetic susceptibilities of the porphyrin rings. The magnitude of the splitting yields an effective value for ΔX, the anisotropy of the susceptibility. This value includes association effects which may be estimated therefrom. Dipolar splittings between protons of attached vinyl groups can also be measured, and provide information about the average dihedral angle between the planes of the vinyl group and porphyrin ring.
1H, 3H and 13C NMR studies on porphobilinogen
Authors: Evans J. N. S. , Fagerness P. E. , Mackenzie N. E. , Scott A. I. 
Published: May 2005

AbstractA key intermediate in porphyrin and corrin biosynthesis is the trisubstituted pyrrole porphobilinogen (PBG). The fate of PBG in the biosynthesis of porphyrins and corrins has been monitored by NMR spectroscopy in vivo and in vitro employing various nuclei. The syntheses of highly tritiated PBG and its immediate precursor 5‐aminolevulinic acid (ALA) are reported, together with 3H, 1H and 13C assignments.
The solution structure of lidocaine: Conformational analysis and NMR lanthanide‐induced shifts
Authors: Laplanche Laurine A. , Vanderkooi Garret , Jasmani Halila , Suki Maimunah Mat 
Published: May 2005

AbstractProton lanthanide‐induced shifts (LIS) were measured for Yb(fod)3—lidocaine complexes in CCl4 solution. The data were used in conjunction with empirical conformational energy calculations to determine the preferred conformations of lidocaine in complex with the lanthanide shift reagent. Energy calculations gave two pairs of symmetry‐related low‐energy conformations for lidocaine. The LIS analysis ruled out, on the basis of poor agreement factors, both members from one possible pair. This combination of methods therefore yielded two low‐energy, good agreement factor, symmetry‐related conformations for lidocaine in solution. These two conformations differ significantly from the reported crystal structure of lidocaine hydrochloride in the value of the NCOCH2N dihedral angle.
Through‐space 19F,19F spin—spin coupling constants in some fluoroallyl cations
Authors: Bakhmutov V. I. , Galakhov M. V. , Fedin E. I. 
Published: May 2005

AbstractThe 4J (19F19F) spin—spin coupling constants in some fluoroallyl cations are discussed. The through‐space contribution to the total spin—spin coupling constant for proximate 19F nuclei is obtained, and the dependence of this contribution on the internuclear distance is defined.
Deuterium isotope effects on 14N and 15N nuclear shielding in simple nitrogen‐containing compounds
Authors: Lyc̆ka Antonin , Hansen Poul Erik 
Published: May 2005

AbstractDeuterium isotope effects on the 14N and 15N nuclear shielding of simple nitrogen‐containing compounds have been investigated. Very similar positive values for 1ΔN(D) have been observed in a series of amides and amines, excluding ammonium ions. Negative values of the deuterium isotope effect over three bonds are observed in acetonitrile and acetanilide. Both coaxial tube and single tube methods have been used, and show comparable results. The additivity of isotope effects over one bond is found to hold for ammonium compounds and amides. Solvent effects were investigated and are shown to be important. The origin of the solvent effects is ascribed to hydrogen bonding.