Selecting Double Bond Positions with a Single Cation-Responsive Iridium Olefin Isomerization Catalyst

2021 ◽  
Vol 143 (7) ◽  
pp. 2792-2800
Author(s):  
Andrew M. Camp ◽  
Matthew R. Kita ◽  
P. Thomas Blackburn ◽  
Henry M. Dodge ◽  
Chun-Hsing Chen ◽  
...  
Keyword(s):  
Double Bond ◽  
Olefin Isomerization ◽  
Isomerization Catalyst

Identifying and Evading Olefin Isomerization Catalyst Deactivation Pathways Resulting from Ion-Tunable Hemilability

ACS Catalysis ◽  
2020 ◽  
Vol 10 (21) ◽  
pp. 13019-13030
Author(s):  
Henry M. Dodge ◽  
Matthew R. Kita ◽  
Chun-Hsing Chen ◽  
Alexander J. M. Miller
Keyword(s):  
Catalyst Deactivation ◽  
Olefin Isomerization ◽  
Isomerization Catalyst

scholarly journals Selecting Double Bond Positions with a Single Cation- Responsive Iridium Olefin Isomerization Catalyst

2020 ◽  
Author(s):  
Andrew M. Camp ◽  
Matthew R. Kita ◽  
Thomas P. Blackburn ◽  
Henry M. Dodge ◽  
Chun-Hsing Chen ◽  
...  
Keyword(s):  
Mechanistic Model ◽  
Computational Studies ◽  
Olefin Isomerization ◽  
Positional Isomerization ◽  
Iridium Catalyst ◽  
Commodity Chemicals ◽  
Covalent Modifications ◽  
Insight Into ◽  
Selective Access ◽  
Isomerization Catalyst

<div><div><div><p>The catalytic transposition of double bonds holds promise as an ideal route to alkenes with value as fragrances, commodity chemicals, and pharmaceuticals; yet, selective access to specific isomers is a challenge, requiring independent development of different catalysts for different products. In this work, a single cation-responsive iridium catalyst is developed for the selective production of either of two different internal alkene isomers. In the absence of salts, a single positional isomerization of 1-butene derivatives furnishes 2-alkenes with exceptional regioselectivity and stereoselectivity. The same catalyst, in the presence of Na+, mediates two positional isomerizations to produce 3-alkenes. The synthesis of new iridium pincer-crown ether catalysts based on an aza-18-crown-6 ether proved instrumental in achieving cation-controlled selectivity. Experimental and computational studies guided the development of a mechanistic model that explains the observed selectivity for various functionalized 1-butenes, providing insight into strategies for catalyst development based on non-covalent modifications.</p></div></div></div>

scholarly journals Selecting Double Bond Positions with a Single Cation- Responsive Iridium Olefin Isomerization Catalyst

2020 ◽  
Author(s):  
Andrew M. Camp ◽  
Matthew R. Kita ◽  
Thomas P. Blackburn ◽  
Henry M. Dodge ◽  
Chun-Hsing Chen ◽  
...  
Keyword(s):  
Mechanistic Model ◽  
Computational Studies ◽  
Olefin Isomerization ◽  
Positional Isomerization ◽  
Iridium Catalyst ◽  
Commodity Chemicals ◽  
Covalent Modifications ◽  
Insight Into ◽  
Selective Access ◽  
Isomerization Catalyst

<div><div><div><p>The catalytic transposition of double bonds holds promise as an ideal route to alkenes with value as fragrances, commodity chemicals, and pharmaceuticals; yet, selective access to specific isomers is a challenge, requiring independent development of different catalysts for different products. In this work, a single cation-responsive iridium catalyst is developed for the selective production of either of two different internal alkene isomers. In the absence of salts, a single positional isomerization of 1-butene derivatives furnishes 2-alkenes with exceptional regioselectivity and stereoselectivity. The same catalyst, in the presence of Na+, mediates two positional isomerizations to produce 3-alkenes. The synthesis of new iridium pincer-crown ether catalysts based on an aza-18-crown-6 ether proved instrumental in achieving cation-controlled selectivity. Experimental and computational studies guided the development of a mechanistic model that explains the observed selectivity for various functionalized 1-butenes, providing insight into strategies for catalyst development based on non-covalent modifications.</p></div></div></div>

Olefin Isomerization Catalysts Based on Dithio Palladium(II) Complexes

1991 ◽  
Vol 44 (2) ◽  
pp. 171 ◽  
Author(s):  
KJ Cavell ◽  
KY Chan ◽  
EJ Peacock ◽  
MJ Ridd ◽  
NW Davies
Keyword(s):  
Double Bond ◽  
Thermodynamic Equilibrium ◽  
Retention Indices ◽  
Palladium Complexes ◽  
Reaction Products ◽  
Olefin Isomerization ◽  
Highly Active ◽  
Kováts Retention Indices ◽  
Product Distributions ◽  
Double Bond Shift

The catalytic double-bond shift isomerization of α-olefins by dithio-β-diketonate palladium complexes Pd{CH3C(S)CHC(S)CH3}(PL1L2L3)X(1) and [Pd{CH3C(S)CHC(S)CH3}{Ph2PCH2CH2PPh2}]Y(2)(X = 1, Br; Y = halide, PF6, BPh4) is described. Catalysts are formed on activation of the complexes by a variety of alkylaluminium cocatalysts . Several of the catalysts are highly active for isomerization of oct-1-ene and but-1-ene, activities being higher than normally obtained for palladium systems. In contrast to the majority of palladium-based catalysts product distributions rapidly approached thermodynamic equilibrium, with a strong preference for trans products at each stage of the reaction. Products from the isomerization of oct-1-ene were analysed by g.l.c.-F.t.i.r . in conjunction with Kovats retention indices.

Stabilities of nickel–alkyl compounds

1970 ◽  
Vol 48 (21) ◽  
pp. 3443-3446 ◽  
Author(s):  
J. Thomson ◽  
M. C. Baird
Keyword(s):  
Thermal Decomposition ◽  
Olefin Isomerization ◽  
Xylene Solution ◽  
Isomerization Catalyst

The compounds π-C5H5Ni(PPh3)R (R = Me, Et, n-Pr, iso-Pr, n-Bu, sec-Bu, iso-Bu) have been prepared and characterized. Thermal decomposition of these compounds in xylene solution yields, in all cases except the methyl, an olefin and an olefin isomerization catalyst.

Azidonitration of a double bond

10.1039/sp72 ◽  
2001 ◽  
Author(s):  
Melanie Reich
Keyword(s):  
Double Bond

THE THYMOLYTIC ACTIVITY OF 6- AND 9-HALOCORTICOIDS AND RELATED STEROIDS

1965 ◽  
Vol 49 (2) ◽  
pp. 262-270 ◽  
Author(s):  
Ralph I. Dorfman ◽  
P. G. Holton ◽  
Fred A. Kind
Keyword(s):  
Double Bond ◽  
Subcutaneous Injection ◽  
Fluocinolone Acetonide ◽  
Relative Potency ◽  
Subcutaneous Route ◽  
Adrenalectomized Rats

ABSTRACT Adrenalectomized rats were used for the determination of the relative potency of various 6- and 9-halo substituted corticoids administered subcutaneously or by gavage using thymus weightas the endpoint. By subcutaneous injection, fluocinolone acetonide was the most active corticoid at 700 times that of cortisol. This compound was also the most active corticoid by the gavage route and was judged to be 570 times as active as the standard cortisol. The introduction of the 16,17-acetonide and 16,17-acetone 21-acetate groups into 17α,21-dihydroxy-9α,11β-dichloropregna-1,4-diene-3,20-dione increased the activity by a factor of 42 and 100, respectively. The introduction of the δ1 double bond into 6α-fluoroprogesterone 16,17-acetonide caused an increase of 10-fold in thymolytic activity assessed by the subcutaneous route

TRIGLYCERIDE COMPOSITION OF SIXTEEN STRAINS OF MARINE DIATOM

2013 ◽  
Vol 5 (1) ◽  
Author(s):  
Lily M.G. Panggabean ◽  
Abdullah Rasyid ◽  
Zarrah Duniani ◽  
Yana Meliana ◽  
Indah Kurniasih
Keyword(s):  
Mass Spectrometry ◽  
Fatty Acid ◽  
Double Bond ◽  
Unsaturated Fatty Acid ◽  
Ion Trap ◽  
Carbon Chain ◽  
Highly Unsaturated Fatty Acid ◽  
Marine Diatom ◽  
Ion Trap Mass Spectrometry ◽  
Spectra Analysis

Trigliceride or triacylglicerol (TAG) composition in crude oil of sixteen strain of marine diatom has been detected by spectra analyses on an Electrospray - Ion Trap – Mass Spectrometry (ESI-IT-MS) HCT Bruker-Daltonic GmbH instrument with AgNO3 used as coordination ionization agent. Biomass samples of each microalga strain were taken from early and late stationary cultures in f/2 enriched seawater and algal oils were extracted according to Bligh and Dyer. Results from spectra analysis showed that P-Pt-P (C16:0-C16:1-C16:0) were distinguished in TAG from diatom strains Chaetoceros sp.1, Chaetoceros sp.2, Thalasiossira sp.1, Thalasiossira sp.2, Thalasiossira sp.3, Navicula sp. 1, Navicula sp. 2, Navicula sp. 3, Navicula sp. 4, Nitzschia sp. 2 and Amphora sp. In contrast, TAGs in Melosira sp. included P-P-P (C16:0-C16:0-C16:0) and P-P-O (C16:0-C16:0-C18:1) were identified. TAGs from Chaetoceros sp. were the most varies among samples, i.e. P-Pt-P (C16:0-C16:1-C16:0), A-P-M (C20:4-C16:0-C14:0), P-Pt-Lt (C16:0-C16:1-C18:3), P-Pt-A (C16:0-C16:1-C20:4), D-P-P (C22:6-C16:0-C16:0), A-Ln-P (C20:4-C18:2-C16:0). Various TAGs were also detected in Nitzschia sp.2, i.e. P-Pt-M (C16:0-C16:1-C14:0), P-Pt-P (C16:0-C16:1-C16:0), P-Pt-S (C16:0-C16:1-C18:0), P-Pt-A (C16:0-C16:1-C20:4). TAGs composition in Skeletonema strains that similar to those in Nitzschia sp.1 has longer carbon, i.e. P-P-O (C16:0-C16:0-C18:1), P-O-O (C16:0-C18:1-C18:1) and O-O-O (C18:1-C18:1-C18:1). TAGs with longer carbon chain and more double bond including highly unsaturated fatty acid C20:4 were increased with culture age in diatoms Chaetoceros sp.1, Chaetoceros sp.2, Thalasiossira sp.2, Navicula sp.1 and Nitzschia sp. 2.Keywords: diatom, TAG, ESI-IT-MS, f/2, early and late stationary

Some Considerations Regarding the 1H and 13C Spectra of 4-(1-azulenyl)-2,6-bis(2-heteroaryl-vinyl)- pyrylium and Pyridinium and their Corresponding Pyridines

2018 ◽  
Vol 69 (1) ◽  
pp. 64-69
Author(s):  
Liviu Birzan ◽  
Mihaela Cristea ◽  
Constantin C. Draghici ◽  
Alexandru C. Razus
Keyword(s):  
Double Bond ◽  
13C Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Pyridinium Salts ◽  
13C Nmr Spectra ◽  
1H And 13C Nmr ◽  
Pyrylium Salts

The 1H and 13C NMR spectra of several 2,6-diheteroarylvinyl heterocycles containing 4-azulenyl moiety were recorded and their proton and carbon chemical shifts were compared with those of the compounds without double bond between the heterocycles. The influence of the nature of central and side heterocycles, molecule polarization and anisotropic effects were revealed. The highest chemical shifts were recorded for the pyrylium salts and the lowest at pyridines, but in the case of the pyridinium salts, the protons chemical shifts at the central heterocycle are more shielded due to a peculiar anisotropy of the attached vinyl groups.

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