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.

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.

The effects controlling the oxygen basicity in alkoxysilanes (RO)nSi(CH3)4-n. The mutual polarizability effect of alkoxy groups attached to silicon

1979 ◽  
Vol 44 (3) ◽  
pp. 750-755 ◽  
Author(s):  
Josef Pola ◽  
Marie Jakoubková ◽  
Václav Chvalovský
Keyword(s):  
Regression Analysis ◽  
Linear Regression ◽  
Electronic Effect ◽  
Linear Regression Analysis ◽  
Effect Of Substituents ◽  
Relative Basicity ◽  
Polarizability Effect ◽  
Alkoxy Groups ◽  
Individual Series

Relative basicity of the oxygen in alkoxysilanes (RO)nSi(CH3)3-n having n = 1-4 and various electrondonating and electronwithdrawing groups R measured as Δν(OH) of phenol due to its interaction with these compounds in CCl4 is shown to be chiefly controlled by the electronic effect of substituents R. Linear regression analysis of the Δν(OH) vs n relatioship for individual series (RO)nSi(CH3)4-n suggests the operation of the polarizability effect of RO groups becoming more important with increasing electronwithdrawing nature of R.

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
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