scholarly journals On the nature of the electronic effect of multiple hydroxyl groups in the 6-membered ring – the effects are additive but steric hindrance plays a role too

2017 ◽  
Vol 15 (5) ◽  
pp. 1164-1173 ◽  
Author(s):  
Christian Marcus Pedersen ◽  
Mikael Bols
Keyword(s):  
Steric Hindrance ◽  
Electronic Effect ◽  
Membered Ring ◽  
Steric Effects ◽  
Hydroxyl Groups ◽  
Base Strength ◽  
Electronic And Steric Effects

Electronic and steric effects each play important roles in determining the base strength in piperidines.

Pyrrole studies. IV. The electronic spectra of alkyl- and ethoxycarbonyldipyrromethenes

1965 ◽  
Vol 18 (3) ◽  
pp. 363 ◽  
Author(s):  
RW Guy ◽  
RA Jones
Keyword(s):  
Electronic Spectra ◽  
Electronic Effect ◽  
Steric Effects ◽  
Steric Interaction ◽  
Effect Of Substituents ◽  
Electronic And Steric Effects

The NH stretching frequency and the electronic spectra of 8 alkyl- and 12 ethoxycarbonyl-dipyrromethenes have been measured and the results correlated with the electronic and steric effects of the substituents. It is postulated that there is steric interaction between the two ethoxycarbonyl groups of 3,3'-diethoxycarbonyl. 4,5,4',5'-tetramethyldipyrromethene. The electronic effect of substituents in the 4,4'-positions of 3,5,3',5'-tetramethyldipyrromethenes is discussed.

Steric effects in quaternizations. Alkylation of pyridine, thiazole, isothiazole and some benzologues with methyl, ethyl and isopropyl iodides

1976 ◽  
Vol 29 (8) ◽  
pp. 1745 ◽  
Author(s):  
LW Deady ◽  
DC Stillman
Keyword(s):  
Steric Hindrance ◽  
Electronic Effect ◽  
Alkyl Halide ◽  
Steric Effects ◽  
Methyl Ethyl ◽  
Rate Retardation

Results of quaternization reactions in sulpholane at 65� are reported. A large steric hindrance is noted for quinoline relative to pyridine. A much smaller variation in rate with change in alkyl halide is seen in the benzothiazole/thiazole pair. Steric effects are very small and the rate retardation resulting from benzofusion is ascribed largely to an electronic effect. 2,l-Benzisothiazole reacts at essentially the same rate as isothiazole under these conditions.

LIGHT ABSORPTION STUDIES: PART I. ULTRAVIOLET ABSORPTION SPECTRA OF SUBSTITUTED ACETOPHENONES

1955 ◽  
Vol 33 (6) ◽  
pp. 1145-1154 ◽  
Author(s):  
W. F. Forbes ◽  
W. A. Mueller
Keyword(s):  
Absorption Spectra ◽  
Ultraviolet Light ◽  
Steric Hindrance ◽  
Light Absorption ◽  
Reaction Rates ◽  
Steric Effects ◽  
Absorption Data ◽  
Absorption Studies ◽  
Anomalous Reaction ◽  
Electronic And Steric Effects

The steric hindrance postulated by Arnold and co-workers to account for anomalous reaction rates of some substituted acetophenones has been verified by means of ultraviolet light absorption data. The spectra of a number of other substituted acetophenones have been discussed in terms of the electronic and steric effects of substituents.

Michael Additions of Benzotriazole-Stabilized Carbanions. A Review

1998 ◽  
Vol 63 (5) ◽  
pp. 599-613 ◽  
Author(s):  
Alan R. Katritzky ◽  
Ming Qi
Keyword(s):  
Steric Hindrance ◽  
Electronic Effect ◽  
Steric Effects ◽  
Unsaturated Ketone ◽  
Electronic Effects ◽  
Michael Additions ◽  
Unsaturated Aldehydes ◽  
Michael Acceptor ◽  
Michael Acceptors ◽  
Electron Withdrawing Group

The 1,4-addition of benzotriazole-stabilized carbanions to Michael acceptors is reviewed. The selectivity between 1,4- and 1,2-addition depends significantly on the electronic effect of the carbanion (usually lithium is the counterion), the type of the Michael acceptor, and steric effects. Steric hindrance of the benzotriazolyl group probably enhances the regioselectivity. Normally, 1,4-additions to α,β-unsaturated ketone or ester are observed for carbanions stabilized by a benzotriazolyl group and an electron-withdrawing group (e.g. aryl, vinyl, carbonyl). For α,β-unsaturated aldehydes as Michael acceptors, 1,2-addition is more likely, except where electronic effects are very strong. A review with 39 references.

Electronic and steric effects on the intramolecular Schmidt reaction of alkyl azides with secondary benzyl alcohols

Tetrahedron ◽  
2014 ◽  
Vol 70 (3) ◽  
pp. 643-649 ◽  
Author(s):  
Xiaowei Sun ◽  
Chengzhe Gao ◽  
Fan Zhang ◽  
Zhuang Song ◽  
Lingyi Kong ◽  
...  
Keyword(s):  
Steric Effects ◽  
Schmidt Reaction ◽  
Benzyl Alcohols ◽  
Alkyl Azides ◽  
Electronic And Steric Effects

The Reactions of Substituted Germyl- and Silylhydrazines with BX3 and CY2 Acceptor Species

1972 ◽  
Vol 50 (4) ◽  
pp. 562-566 ◽  
Author(s):  
L. K. Peterson ◽  
K. I. Thé
Keyword(s):  
Molecular Weight ◽  
Nitrogen Atom ◽  
Low Temperatures ◽  
Adduct Formation ◽  
Steric Effects ◽  
Reaction Products ◽  
Hydrazine Derivatives ◽  
Basic Catalysts ◽  
Series Of Experiments ◽  
Electronic And Steric Effects

Boron trimethyl reacts with each of the organometalloid-hydrazine derivatives Me2NN(R)GeMe3 (R = H, Me, SiMe3) except Me2NN(SiMe3)GeMe3, and with Me2NNHSiMe3, forming 1:1 adducts. With Me2NN(SiMe3)GeMe3 and BMe3, no adduct was formed even at low temperatures. On the basis of p.m.r. spectra, the metalloid-substituted nitrogen atom rather than the terminal nitrogen, is indicated as the basic center at which adduct formation occurs. With BF3, the Si—N and Ge—N bonds of the hydrazine derivatives were cleaved, again indicating attack at the central nitrogen atom. In a series of experiments involving CY2 (Y = O, S) and Me2NN(R)MMe3 (R = H, Me, SiMe3; M = Si, Ge), reaction occurred readily for R = H, but less readily for R = Me and for the compound Me2NN(GeMe3)2, while no reaction was observed for the compounds Me2NN(SiMe3)2 and Me2NN(SiMe3)GeMe3, even when heat or basic catalysts were employed. Reaction products, carbamate and thiocarbamate derivatives, Me2NN(R)C(Y)YMMe3, were characterized on the basis molecular weight, i.r., p.m.r., and mass spectroscopy, and m.p. data. Ease of formation is discussed in terms of electronic and steric effects.

Highly Stereo- and Regioselective Allylations Catalyzed by Mo−Pyridylamide Complexes:  Electronic and Steric Effects of the Ligand

2000 ◽  
Vol 65 (18) ◽  
pp. 5868-5870 ◽  
Author(s):  
Oscar Belda ◽  
Nils-Fredrik Kaiser ◽  
Ulf Bremberg ◽  
Mats Larhed ◽  
Anders Hallberg ◽  
...  
Keyword(s):  
Steric Effects ◽  
Electronic And Steric Effects
Sign in / Sign up

Export Citation Format

Share Document