Results 111 to 120 of about 2,266 (161)
Some of the next articles are maybe not open access.
Drug Development and Industrial Pharmacy, 2020
It was of interest to correlate the solid-state acidity to the decomposition of a model drug namely cefotaxime sodium. Amorphous samples containing either an indicator probe (thymol blue) or a model drug (cefotaxime sodium) were prepared by freeze-drying. The prepared samples were characterized using XRPD and Karl Fischer titrimetry. The acidity in the
Bashar M, Altaani +3 more
openaire +2 more sources
It was of interest to correlate the solid-state acidity to the decomposition of a model drug namely cefotaxime sodium. Amorphous samples containing either an indicator probe (thymol blue) or a model drug (cefotaxime sodium) were prepared by freeze-drying. The prepared samples were characterized using XRPD and Karl Fischer titrimetry. The acidity in the
Bashar M, Altaani +3 more
openaire +2 more sources
Validation of Hammett’s Linear Free Energy Relationship Through an Unconventional Approach
The Journal of Physical Chemistry A, 2020The present study tries to validate Hammett's linear free energy relationship through an unconventional approach based on the density functional reactivity theory (DFRT). A kinetic energy component [ΔEB(A)], derived from the DFRT-based comprehensive decomposition analysis of stabilization energy scheme, is used to verify the linear nature of Hammett's ...
Aabid Hamid, Ram Kinkar Roy
openaire +2 more sources
Probing the Reactivity of Solid Supports via Hammett Relationships
Journal of the American Chemical Society, 2000A high-throughput technique for elucidating Hammett relationships on solid supports and its application to the comparison of various commercially available solid supports is reported. Specifically, we report the use of competition experiments to derive Hammett relationships for the displacement of a solid-supported pentafluorophenyl (pfp) ester with ...
Samuel W. Gerritz +2 more
openaire +1 more source
Nonlinear Hammett relationships
Journal of Chemical Education, 1971The author provides examples of nonlinear structure-reactivity , Hammett correlation's, and summarize most of the types of reactions in which deviations due to change in mechanism or rate-controlling step occur.
openaire +1 more source
The Journal of Physical Chemistry A, 2008
The photochemical reaction dynamics of a set of photochromic compounds based on thioindigo and stilbene molecular parts (hemithioindigos, HTI) are presented. Photochemical Z/E isomerization around the central double bond occurs with time constants of 216 ps (Z --> E) and 10 ps (E --> Z) for a 5-methyl-hemithioindigo.
Cordes, Thorben +4 more
openaire +3 more sources
The photochemical reaction dynamics of a set of photochromic compounds based on thioindigo and stilbene molecular parts (hemithioindigos, HTI) are presented. Photochemical Z/E isomerization around the central double bond occurs with time constants of 216 ps (Z --> E) and 10 ps (E --> Z) for a 5-methyl-hemithioindigo.
Cordes, Thorben +4 more
openaire +3 more sources
Canadian Journal of Chemistry, 1965
The overlapping ionization constants of the carboxyl and amino groups in 14 substituted anthranilic acids have been determined by a spectrophotometric method. The results have been fitted to the extended Hammett relationship log K1K2/K10K20 = ρ1σA + ρ2σB, where A and B refer to ionization of the carboxyl and amino group, respectively. The values of ρ1
P. Leggate, G. E. Dunn
openaire +1 more source
The overlapping ionization constants of the carboxyl and amino groups in 14 substituted anthranilic acids have been determined by a spectrophotometric method. The results have been fitted to the extended Hammett relationship log K1K2/K10K20 = ρ1σA + ρ2σB, where A and B refer to ionization of the carboxyl and amino group, respectively. The values of ρ1
P. Leggate, G. E. Dunn
openaire +1 more source
Journal of Physical Organic Chemistry, 2023
AbstractHydrazone derivatives ofβ‐dicarbonyl compounds illustrate an integrated configurational and conformational changes, which make them be considered as probe in disclosing H‐bonding importance in hydrogen transfer and switching. The ethyl‐3‐oxo‐butanoate derivatized hydrazones were synthesized by Japp–Klingemann reaction and were characterized in ...
Mohammad Reza Zamanloo +5 more
openaire +1 more source
AbstractHydrazone derivatives ofβ‐dicarbonyl compounds illustrate an integrated configurational and conformational changes, which make them be considered as probe in disclosing H‐bonding importance in hydrogen transfer and switching. The ethyl‐3‐oxo‐butanoate derivatized hydrazones were synthesized by Japp–Klingemann reaction and were characterized in ...
Mohammad Reza Zamanloo +5 more
openaire +1 more source
Structure—property relationships and momentum space quantities: Hammett σ—constants
Molecular Physics, 2003Correlations are established between Hammett σ constants and momentum-space expectation values ( ). Momentum-space quantities, which have generally been neglected by chemists, are shown to be valuable for such problems, which suggests they may be useful more widely as suitable molecular descriptors for quantitative structure-property studies.
LLUÍS AMAT +4 more
openaire +1 more source
The I ? effect. Part II. Hammett relationships
Journal of the Chemical Society B: Physical Organic, 1968The treatment of substituent effects on the properties of benzenoid compounds described in Part I is developed to allow the derivation of Hammett relationships for the ionization of acids and for electrophilic substitution. Theoretical σ-constants are evaluated.
openaire +1 more source
Hammett-type relationship for the cleavage of radical anions of aromatic chlorides and bromides
Tetrahedron, 2005Abstract A Hammett-type correlation pertaining to the cleavage of radical anions of aromatic halides has been formulated. The expression has been verified using the reaction series of aromatic chlorides and bromides. The correlation reveals the sensitive nature of the carbon–chlorine bond to the polar effects of the substituents in comparison to the ...
M. Arun Prasad, M.V. Sangaranarayanan
openaire +1 more source