Steric hindrances

DIASTEREOMERS STEREOSELECTIVITY STEREOSPECIFICITY STERIC-APPROACH CONTROL STERIC HINDRANCE Steric hindrance effect on ligand binding, SCATCHARD RLOT Stern layer,... 

The substituent groups in the cis position may crowd each other a condition known as steric hindrance. Steric hindrance in cis molecules produces higher energy levels resulting in higher heats of combustion. 

Irving, Cabell, and Mellor found that 2-methyl-l,10-phenanthroline is a stronger base than 1,10-phenanthroline yet it forms weaker complexes with Fe(II). The relative instability of the Fe(III) complex with 1,10-phenanthroline compared with the Fe(n) complex also seems to be due, at least in part, to steric hindrance. Steric hindrance plays an important role in the use of the reagent 2-methyl-8-hydroxy-quinoline, which precipitates zinc and magnesium but not aluminum. ... 

Steric effects are caused by groups occupying a certain volume of space. A steric effect that decreases reactivity is called steric hindrance. Steric hindrance results when groups are in the way at the reaction site. Steric hindrance causes alkyl halides to... 

Hexen-l-yn-3-one, 1-methoxy spiroanellation with, 74 Hexonamides, TV-alkyl- aqueous suspensions various micellar aggregates, 352-353 L-Hexoses total synthesis, 264-265 2-Hexulosides by redox glycosylation , 272 High-dilution methods macrocycle syntheses by, 145-146, 240-241, 329, 338 Hindrance, steric. See Steric hindrance Hippuric acid See Glycine, iV-bcnzoyl-HMDS. See Silanamine,. .. 

The synclinal (gauche) conformation is higher in energy (by 4kJmol ) as the two methyl groups are near one another (60° separation) resulting in steric strain (steric hindrance). Steric strain is the repulsive interaction between two groups which are closer to one another than their atomic radii allow. 

Hexokinase as reagent 18, 151 High dilution, technique s. under Ring closure Hindrance, steric (s. a. 

Substitution. The kinetics of reactions of /ra/t -CPdClgCR SR ) ] complexes with a series of amines of various basicities and steric requirements have been studied in 1,2-dimethoxyethane at 298 K. In fact the first step is fast, and it is the second step whose kinetics have been examined here. Amine basicity is an important factor logarithms of second-order rate constants correlate linearly with amine pKa values in the absence of steric hindrance. Steric factors have a large effect when the incoming amine e.g. 2-methylpyridine) or the leaving sulphide (e.g. phenyl isopropyl sulphide) is bulky. The kinetic pattern for the reaction of [PdCl2(cod)] with 2,2 -bipyridyl in aqueous methanol has been interpreted by the reaction sequence shown in Scheme 3. The mechanism is dissociative with respect to the palladium centre. The rate law for the reaction of the [PdBr(dien)]+ cation with inosine has already been discussed in the introductory section to this chapter. 

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