SOME STUDIES OF SLOW ROTATIONS AROUND BONDS IN AMIDES

1966 ◽  
Vol 44 (20) ◽  
pp. 2387-2394 ◽  
Author(s):  
T. H. Siddall III ◽  
R. H. Garner
Keyword(s):  
Nitrogen Atom ◽  
Benzene Ring ◽  
Rapid Rate ◽  
Electronic Effects ◽  
Substituted Benzamides ◽  
Carbonyl Bond ◽  
Related Compounds ◽  
Nitrogen Bond

Studies were made of the relative rates of rotation around the benzene-to-carbonyl, carbonyl-to-nitrogen, and nitrogen-to-benzene bonds in some α-naphthamides, o-substituted benzamides, and related compounds. In general bulky substituents on the nitrogen atom tend to increase the rate of rotation around the carbonyl-to-nitrogen bond, but to decrease the rate around the benzene-to-carbonyl bond. Naphthanilides with o-substitution in the benzene ring have a rapid rate of rotation around the naphthalene-to-carbonyl bond compared with other naphthamides. Relative rates of rotation can be rationalized on the basis of combined steric and electronic effects.

Factors Promoting Alkene Migratory Insertion into Metal-Nitrogen Bond during Hydroamination in Recent Studies

2021 ◽  
Vol 18 ◽  
Author(s):  
Wenlai Han
Keyword(s):  
Transition Metal ◽  
Late Transition Metal ◽  
Electronic Effects ◽  
Metal Centers ◽  
Unsaturated Bond ◽  
Factors Influencing ◽  
Migratory Insertion ◽  
Late Transition ◽  
Metal Catalyzed ◽  
Nitrogen Bond

: Migratory insertion is a fundamental organometallic transformation that enables the functionalization of an unsaturated bond. Recent reports on catalytic hydroamination provide evidence that supports an intermolecular migratory insertion pathway featuring alkene insertion into metal-nitrogen (M-N) bonds. This article presents factors influencing the rate of migratory insertion in late-transition metal-catalyzed hydroamination, including steric and electronic effects from ligands, alkenes, and metal centers, along with stabilization from coordinated amine intermediates and ordered transition states.

Carbon–nitrogen bond cleavage of pyridine with two molecular substituted allenoates: access to 2-arylpyrimidin-4(3H)-one

2018 ◽  
Vol 54 (100) ◽  
pp. 14128-14131 ◽  
Author(s):  
Tao Jin ◽  
Hongdong Yuan ◽  
Shikuan Su ◽  
Xueshun Jia ◽  
Chunju Li ◽  
...  
Keyword(s):  
Benzene Ring ◽  
Ring Opening ◽  
Pyridine Ring ◽  
Bond Cleavage ◽  
Ring System ◽  
Nitrogen Bond

A DABCO-catalyzed annulation reaction of pyridin-2-amine and substituted allenoates enables the ring-opening of a pyridine ring system and the formation of two new rings including a pyrimidinone ring and a benzene ring.

Transmission of electronic effects in 4-aryl-2,6-diphenylpyrylium perchlorates and related compounds

1996 ◽  
Vol 9 (9) ◽  
pp. 631-638 ◽  
Author(s):  
Danuta Rasa?a ◽  
Tomasz B?k ◽  
Erkki Kolehmainen ◽  
Stanis?aw Styrcz ◽  
Ryszard Gawinecki
Keyword(s):  
Electronic Effects ◽  
Related Compounds

Proton Magnetic Resonance Spectra of Some Amphetamines and Related Compounds and Observations on Rotamer Populations

1971 ◽  
Vol 49 (19) ◽  
pp. 3143-3151 ◽  
Author(s):  
K. Bailey ◽  
A. W. By ◽  
K. C. Graham ◽  
D. Verner
Keyword(s):  
Hydrogen Bonding ◽  
Phenyl Ring ◽  
Proton Magnetic Resonance ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Side Chain ◽  
Amino Group ◽  
Ortho Position ◽  
Electronic Effects ◽  
Related Compounds

Data from the p.m.r. spectra of β-amino-, β-aminohydrochloride-, β-hydroxy-, and β-nitro-α-phenyl-propanes having methyl or methoxy substituants on the phenyl ring (37 compounds in all) are presented. The α and β protons of the side-chain give a pattern usually analyzable as ABX. The data are discussed in terms of correlations of coupling constants and chemical shifts with electronegativity of the substituent groups, steric and electronic effects, and apparent changes in rotamer populations. Hydrogen-bonding between the amino group of amphetamines and a methoxyl function at the ortho position in the phenyl ring is indicated for the salts but not the free bases.

Sur l'aptitude à l'extension du noyau pipéridique en fonction de la substitution de l'atome d'azote: réaction du diazométhane avec quelques pipéridones-4 et désamination nitreuse des aminométhyl-alcools correspondants

1971 ◽  
Vol 49 (19) ◽  
pp. 3075-3085 ◽  
Author(s):  
H. Favre ◽  
Z. Hamlet ◽  
R. Lanthier ◽  
M. Ménard
Keyword(s):  
Nitrogen Atom ◽  
Carbonyl Group ◽  
Nitrous Acid ◽  
Ring Expansion ◽  
Nucleophilic Attack ◽  
Electronic Effects ◽  
Field Effects ◽  
Benzoyl Group ◽  
La Substitution

Aptitude to ring expansion in the piperidine series, measured by the ratio of ring expanded ketone to epoxide, varies considerably according to the nitrogen atom substituent. This ratio is essentially the same in the case of the reaction of diazomethane on 4-piperidones and the nitrous acid deamination of the corresponding aminoalcohols. The values of the ratio are 0.01–0.1 for a phenylsulfonyl group, of the order 0.3–0.6 for a benzoyl group and slightly greater than 1 for a benzyl group. Electronic effects (inductive and field effects) are the cause of these differences. Parallels between the two reactions indicate that nucleophilic attack of diazomethane on the carbonyl group can lead to the ring expanded ketone and the epoxide.

Carbamylphosphonates and Related Compounds—Nuclear-Magnetic-Resonance and Infrared Spectra

1967 ◽  
Vol 21 (1) ◽  
pp. 9-15 ◽  
Author(s):  
T. H. Siddall ◽  
C. A. Prohaska
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Infrared Spectra ◽  
Proton Magnetic Resonance ◽  
Structural Features ◽  
Slow Rotation ◽  
The Common ◽  
Related Compounds ◽  
Great Evidence ◽  
Nitrogen Bond

Proton magnetic resonance and infrared spectra were obtained for 44 carbamylphosphonates and related compounds, the common structural features being the grouping As with ordinary amides, slow rotation is observed around the carbonyl-to-nitrogen bond, but the chemical shift between nitrogen substituents is three to five times as great. Evidence is presented for long range coupling of phosphorus to protons in N-substituents. Correlations are observed between the carbonyl and phosphoryl stretching frequencies and substituents both on nitrogen and on phosphorus.

scholarly journals The theory of the stability of the benzene ring and related compounds

1934 ◽  
Vol 146 (856) ◽  
pp. 223-238 ◽  
Keyword(s):  
Benzene Ring ◽  
Accurate Solution ◽  
Great Length ◽  
Carbon Nucleus ◽  
Electron Pairs ◽  
Best Value ◽  
Single Ring ◽  
Ring Structures ◽  
The Stability ◽  
Related Compounds

There are two fairly distinct problems involved in a treatment of the stability of the benzene ring. The first is to explain why of all the single-ring structures C n H n , that of benzene ( n = 6) is by far the most stable. The second is to examine the different models proposed by the chemists for the benzene ring in the light of quantum mechanics and to show in fact that they are all represented with varying probabilities in the complete model. Attempts have been made at both problems, but only the second has been worked out satisfactorily. In the present paper we attempt a more accurate solution than has hitherto been given of the first problem. Before commencing this it is necessary to give a description of previous work, since otherwise it is very difficult to see what is already certain and what remains to be done. In a series of papers Hückel has discussed at great length both of the problems mentioned above, not only for the simple benzene ring, but also for many of its substitution products. He evaluates the energy of the plane ring compound in two ways, one of which virtually amounts to the method of generalized electron pairs and the other to that of molecular orbitals. The chief weakness in his theory is that he considers only what he calls the p r electrons, viz., the n 2 p -electrons whose wave functions are odd for reflection in the plane of the ring. As we shall show, the three remaining bonding electrons on each carbon nucleus have a most important influence on the best value of n . Nevertheless, Hückel's work is quite satisfactory as regards the resonance between the p r electrons.

NITROLYSIS OF HEXAMETHYLENETETRAMINE: V. 1,7-DINITROXY-2,4,6-TRINITRO-2,4,6-TRIAZAHEPTANE AND RELATED COMPOUNDS

1949 ◽  
Vol 27b (6) ◽  
pp. 503-519 ◽  
Author(s):  
A. F. McKay ◽  
R. H. Meen ◽  
George F Wright ◽  
W. J. Chute ◽  
G. S. Myers
Keyword(s):  
Nitric Acid ◽  
Nitrogen Atom ◽  
Ammonium Nitrate ◽  
Cyclic Nitramines ◽  
Related Compounds

When hexamethylenetetramine is nitrolyzed with nitric acid and an anhydride in absence of ammonium nitrate the synthesis of cyclic nitramines is decreased and the yields of esterified linear tetramethylenetrinitramines are increased. The two remaining carbon atoms and one nitrogen atom in hexamine can be accounted as esterified dimethylolnitramide. The isolation of a trace of linear pentamethylenetetranitramine from a normal nitrolysis of hexamethylenetetramine shows that in all of these reactions a common intermediate, dimethylolaminomethyldinitrotriazacyclohexane, must be present. This has never been isolated, but its reactions can be deduced from the behavior of methylene-bis-3,5-dinitro-1,3,5-triazacyclohexane.

Torsional angles in N-substituted benzamides and related compounds by carbon-13 N.M.R. chemical shifts

1981 ◽  
Vol 34 (5) ◽  
pp. 957 ◽  
Author(s):  
CW Fong ◽  
HG Grant
Keyword(s):  
Steric Effect ◽  
Chemical Shifts ◽  
Steric Interaction ◽  
Hydrogen Atoms ◽  
Ring Inversion ◽  
Nitrogen Inversion ◽  
Substituted Benzamides ◽  
Substituent Constants ◽  
Torsional Angles ◽  
Related Compounds

The torsional angles in 30 N-substituted benzamides and related compounds have been estimated by the use of the 13C substituent chemical shifts of the meta and para carbon atoms. Steric interaction between the N-substituted groups and the ortho hydrogen atoms of the benzene ring is the major determinant of non-planarity in these systems. A linear relationship between steric substituent constants of the N-substituted groups of some benzamides and the torsional angles is proposed. Dynamic processes involving rotation about the C-N bond, nitrogen inversion and ring inversion contribute a dynamic steric effect to the overall steric interaction. The preferred conformations of some N-substituted groups is also discussed.

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