34979-35-6Relevant articles and documents
Supported Rhodium Nanoparticles Catalyzed Reduction of Nitroarenes, Arylcarbonyls and Aryl/Benzyl Sulfoxides using Ethanol/Methanol as In Situ Hydrogen Source
Sharma, Saurabh,Bhattacherjee, Dhananjay,Das, Pralay
supporting information, p. 2131 - 2137 (2018/04/17)
A facile reduction reaction of nitroarenes, aryl carbonyls and aryl/benzyl sulfoxides was performed under polystyrene supported rhodium (Rh@PS) catalyzed conditions using ethanol/methanol as in situ hydrogen source. The catalyst Rh@PS played a pivotal role in the oxidation of ethanol/methanol in the presence of traces of aerial oxygen and base to produce hydrogen gas, enough for further reduction reaction. Transmission electron microscopy (TEM) analysis indicated that the average particle size of the Rh nanoparticles (NPs) lies between 2–3 nm; this is responsible for its high catalytic activity. The advantages of Rh@PS are its catalytic activity, easy preparation, recovery, recyclability for several runs, and low metal leaching during reaction. (Figure presented.).
Ion-pairing of phosphonium salts in solution: C-H...halogen and C-H...π hydrogen bonds
Ammer, Johannes,Nolte, Christoph,Karaghiosoff, Konstantin,Thallmair, Sebastian,Mayer, Peter,Devivie-Riedle, Regina,Mayr, Herbert
, p. 14612 - 14630 (2013/11/06)
The 1HNMR chemical shifts of the C(α)-H protons of arylmethyl triphenylphosphonium ions in CD2Cl2 solution strongly depend on the counteranions X-. The values for the benzhydryl derivatives Ph2CH-PPh3+ X -, for example, range from δH=8.25 (X -=Cl-) over 6.23 (X-=BF4 -) to 5.72ppm (X-=BPh4-). Similar, albeit weaker, counterion-induced shifts are observed for the ortho-protons of all aryl groups. Concentration-dependent NMR studies show that the large shifts result from the deshielding of the protons by the anions, which decreases in the order Cl- > Br- a‰ BF4 - > SbF6-. For the less bulky derivatives PhCH2-PPh3+ X-, we also find C-H...Ph interactions between C(α)-H and a phenyl group of the BPh4- anion, which result in upfield NMR chemical shifts of the C(α)-H protons. These interactions could also be observed in crystals of (p-CF3-C6H4)CH2-PPh 3+ BPh4-. However, the dominant effects causing the counterion-induced shifts in the NMR spectra are the C-H...X- hydrogen bonds between the phosphonium ion and anions, in particular Cl- or Br-. This observation contradicts earlier interpretations which assigned these shifts predominantly to the ring current of the BPh4- anions. The concentration dependence of the 1HNMR chemical shifts allowed us to determine the dissociation constants of the phosphonium salts in CD2Cl2 solution. The cation-anion interactions increase with the acidity of the C(α)-H protons and the basicity of the anion. The existence of C-H...X- hydrogen bonds between the cations and anions is confirmed by quantum chemical calculations of the ion pair structures, as well as by X-ray analyses of the crystals. The IR spectra of the Cl- and Br- salts in CD2Cl2 solution show strong red-shifts of the C-H stretch bands. The C-H stretch bands of the tetrafluoroborate salt PhCH 2-PPh3+ BF4- in CD 2Cl2, however, show a blue-shift compared to the corresponding BPh4- salt.
The reactivity of benzoates in mixtures of water and aprotic solvents
Matic, Mirela,Denegri, Bernard,Kronja, Olga
, p. 585 - 594 (2013/06/26)
Nucleofugalities of pentafluorobenzoate (PFB), 2,4,6-trifluorobenzoate (TFB), 2-nitrobenzoate, and 3,5-dinitrobenzoate (DNB) leaving groups have been derived from the solvolysis rate constants of the corresponding X,Y-substituted Z-benzhydryl benzoates in
Exploring the structure-activity relationship of the ethylamine portion of 3-iodothyronamine for rat and mouse trace amine-associated receptor 1
Tan, Edwin S.,Miyakawa, Motonori,Bunzow, James R.,Grandy, David K.,Scanlan, Thomas S.
, p. 2787 - 2798 (2008/02/06)
3-Iodothyronamine (1, T1AM) is a naturally occurring derivative of thyroid hormone that can potently activate the orphan G protein-coupled receptor (GPCR) known as the trace amine-associated receptor 1 (TAAR 1). We have previously found that modifying the outer ring of the phenoxyphenethylamine core scaffold of 1 can improve potency and provide potent agonists. In this study, we explored the tolerance of rat and mouse TAAR 1 (rTAAR1 and mTAAR1) for structural modifications in the ethylamine portion of 1. We found that incorporating unsaturated hydrocarbon substituents and polar, hydrogen-bond-accepting groups were beneficial for rTAAR1 and mTAAR1, respectively, providing compounds that were equipotent or more potent than 1. Additionally, we have discovered that a naphthyl group is an excellent isosteric replacement for the iodophenyl ring of 1.
Thyronamine derivatives and analogs and methods of use thereof
-
, (2008/06/13)
Thyronamine derivatives and analogs, methods of using such compounds, and pharmaceutical compositions containing them are disclosed. Methods of preparing such compounds are also disclosed
SN1 reactions with inverse rate profiles
Denegri, Bernard,Minegishi, Shinya,Kronja, Olga,Mayr, Herbert
, p. 2302 - 2305 (2007/10/03)
Carbocations may accumulate during solvolysis reactions! The fact that fast ionization followed by slow trapping of the carbocation R+ is a characteristic pattern of many solvolysis reactions requires that the generally accepted energy profiles of these reactions be revised.
Ionisation and Dissociation of Diarylmethyl Chlorides in BCl3/CH2Cl2 Solution: Spectroscopic Evidence for Carbenium Ion Pairs
Schneider, Reinhard,Mayr, Herbert,Plesch, Peter H.
, p. 1369 - 1374 (2007/10/02)
The ionisation equilibria of diarylmethyl chlorides Ar2CHCl (Ar = p-CH3O-C6H4, p-PhO-C6H4, p-CH3-C6H4) reacting with BCl3 in CH2Cl2 to give ion-pairs Ar2CH(+)BCl4(-) (KI), and the dissociation of these (KD) were studied by conductimetry and spectro-photometry.The molar conductivities are almost independent of the nature of the aryl group (ca. 3.5E-3 Sm2/mol at -70 deg C).The ionisation constants KI increase strongly with increasing electron releasing ability of the p-substituents.The standard ionisation enthalpies and entropies for (p-CH3-C6H4)2CHCl and (p-PhO-C6H4)(Ph)CHCl, calculated from the KI at different temperatures are negative.The dissociation constants KD do not show a systematic dependence on the electron donating abilities of the substituents in the aryl groups.Small differences between the UV-vis absorption spectra of unpaired and paired ions were used to confirm the conductimetrically determined values of KD. - Key words: Carbocations / Electrochemistry / Ionisation / Spectroscopy, Visible / Thermodynamics
