366. Hydrolysis of arylsulphuric acids. Part IV. (a) Conjugation between the benzene nucleus and unsaturated side chains. (b) Steric effects and the influence of alkyl groups.

1936 ◽  
pp. 1654 ◽  
Author(s):  
G. Norman Burkhardt ◽  
Charles Horrex ◽  
Doreen I. Jenkins
Keyword(s):  
Steric Effects ◽  
Side Chains ◽  
Benzene Nucleus ◽  
Alkyl Groups ◽  
Hydrolysis Of

Alkyl 1-[2-(oxido anion)-, 3-, 4-, 5-alkyl substituted]phenyl ketyl radicals

1979 ◽  
Vol 44 (6) ◽  
pp. 1731-1741 ◽  
Author(s):  
Andrej Staško ◽  
Ľubomír Malík ◽  
Alexander Tkáč ◽  
Vladimír Adamčík ◽  
Eva Maťašová
Keyword(s):  
Electron Donor ◽  
Unpaired Electron ◽  
Grignard Reagents ◽  
Slight Effect ◽  
Benzene Nucleus ◽  
Alkyl Groups ◽  
Splitting Constant

Reactions of R2,R3-alkyl substituted 2-hydroxybenzenecarboxylic acids 2-HO-C6H2R2-COOH with Grignard reagents R1MgBr in the presence of nickel give stable aryl alkyl ketyl radicals 2-O--R2-, R3-C6H2-CO--R1 where R1 = CH3, C2H5, C2D5, n-C3H7 and R2,R3 = CH3, C2H5, i-C3H7, t-C4H9. The β protons of ketyl group are equivalent (splitting constant 1.25 mT) and non-equivalent (splitting constants within 0.5 to 1.5 mT) for R1 = methyl and other alkyl groups, respectively. Interaction of the γ protons with the unpaired electron was only observed in the case of R1 = n-propyl (splitting constants about 0.07 mT). The substituents R1 have but slight effect on values of splitting constants of the protons in R2,R3 and vice versa. Also splitting constants of the benzene nucleus (a4H = 0.55 mT, a6H = 0.44 mT) are only slightly affected by the substituents R1,R2,R3, which indicates dominant electron-donor effect of the oxido-anion group eliminating the relatively smaller contributions of the alkyl substituents.

Synthesis and Tautomerism of Curcumin Derivatives and Related Compounds

2015 ◽  
Vol 68 (2) ◽  
pp. 224 ◽  
Author(s):  
Hiroyasu Taguchi ◽  
Daijiro Yanagisawa ◽  
Shigehiro Morikawa ◽  
Koichi Hirao ◽  
Nobuaki Shirai ◽  
...  
Keyword(s):  
Parent Compound ◽  
Amyloid Plaques ◽  
Enol Form ◽  
19F Nmr ◽  
Enolic Form ◽  
Curcumin Derivatives ◽  
Alkyl Groups ◽  
Alzheimer Brain ◽  
Hydrolysis Of ◽  
Related Compounds

1,7-Bis(4′-hydroxy-3′-trifluoromethoxyphenyl)-1,6-heptadiene-3,5-dione (2a), related to curcumin, and thirteen 4-substituted derivatives were prepared and their keto/enol ratio in DMSO[D6] was determined by 19F NMR because the enolic form of these related curcumins had been shown to bind to amyloid plaques in the Alzheimer brain. The parent compound and the 4-ethoxycarbonyl derivative were almost 100 % in the enolic form that contains a conjugated hepta-1,4,6-trien-3-on-5-ol backbone. Enolisation decreased to varying amounts in the derivatives that had 4-substituted alkyl groups. Attempts to prepare the 4-hydroxypropyl derivative by hydrolysis of O-methoxymethyl 2m or O-tetrahydropyranyloxy 2n protected derivatives led to cyclised products. A related pyrimidine compound 6b that mimicked a fixed enol form was also prepared.

scholarly journals Controlled steric selectivity in molecular doping towards closest-packed supramolecular conductors

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Shinya Kohno ◽  
Yu Yamashita ◽  
Naotaka Kasuya ◽  
Tsubasa Mikie ◽  
Itaru Osaka ◽  
...  
Keyword(s):  
Conjugated Polymers ◽  
Steric Effects ◽  
Side Chain ◽  
Side Chains ◽  
Void Space ◽  
Alkyl Side Chains ◽  
Recent Developments ◽  
High Carrier ◽  
Molecular Doping ◽  
Steric Selectivity

Abstract Recent developments in molecular doping technologies allow extremely high carrier densities in polymeric semiconductors, exhibiting great diversity because of the unique size, conformation, and steric effect of molecular dopants. However, it is controversial how steric effects can limit the doping efficiency and to what extent dopants can be accommodated in polymers. Here, we employ two distinct conjugated polymers with different alkyl side-chain densities, where polymers are doped via anion-change, allowing greater variation in the incorporation of molecular dopants having different electrostatic potentials and shapes. We characterize the doping efficiency with regard to steric effects, considering the unique void space in the conjugated polymers. Our study reveals that doping efficiency of polymers with sparse alkyl side-chains is significantly greater than that with dense side-chains. A closest-packed supramolecule is realized with a particular combination of a sparse polymer and a large dopant, giving rise to high conductivity, air stability, and remarkably high work function. This work provides a critical insight into overcoming steric effects in molecular doping.

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