scholarly journals Catalytic β-Bromohydroxylation of Natural Terpenes: Useful Intermediates for the Synthesis of Terpenic Epoxides

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Saadia Oubaassine ◽  
Angela Köckritz ◽  
Reinhard Eckelt ◽  
Andreas Martin ◽  
Mustapha Ait Ali ◽  
...  

In a one-step procedure, various β-bromoalcohols were synthesized from natural terpenes in good to excellent yields. Using different catalysts, the reaction was carried out at room temperature, with H2O as nucleophile and N-bromosuccinimide as a bromine source under mild reaction conditions. The synthesized β-bromoalcohols were subsequently converted in situ to the corresponding epoxides in good yields.

2019 ◽  
Vol 41 (6) ◽  
pp. 1039-1039
Author(s):  
Yingguo Fang and Jie Yan Yingguo Fang and Jie Yan

A novel and efficient alkoxylselenenylation from alkenes, diselenides, and alcohols mediated by iodine is developed, with which a series of β-alkoxy selenides are synthesized. In this procedure, firstly, I2 reacts with diselenide to form in situ the active electrophilic selenium species RSeI, then following an electrophilic addition of it to alkenes provides β-alkoxy selenides with high regioselectivity and in good yields. This new method for achieving β-alkoxy selenides has some advantages over other methods such as using available and cheap iodine as the oxidizing species at room temperature, which makes this reaction has milder reaction conditions and simpler procedure.


Nanoscale ◽  
2017 ◽  
Vol 9 (36) ◽  
pp. 13820-13827 ◽  
Author(s):  
Sayantan Chatterjee ◽  
Uday Maitra

We describe a practical, one step, room temperature in situ synthesis of luminescent CdSe QDs using a bile salt derived metallogel, followed by their isolation from the gel and re-dispersion in an organic solvent.


2001 ◽  
Vol 73 (7) ◽  
pp. 1087-1101 ◽  
Author(s):  
John Meurig Thomas ◽  
Robert Raja ◽  
Gopinathan Sankar ◽  
Robert G. Bell ◽  
Dewi W. Lewis

There is a pressing need for: (i) cleaner fuels (free of aromatics and of minimal sulfur content) or ones that convert chemical energy directly to electricity, silently and without production of noxious oxides and particulates; (ii) chemical, petrochemical, and pharmaceutical processes that may be conducted in a one-step, solvent-free manner, and that use air as the preferred oxidant; and (iii) industrial processes that minimize consumption of energy, production of waste or the use of corrosive, explosive, volatile and nonbiodegradable materials. All these needs and other desiderata, such as the in situ production and containment of aggressive and hazardous reagents, and the avoidance of use of ecologically harmful elements, may be achieved by designing the appropriate heterogeneous inorganic catalyst, which, ideally should be cheap, readily preparable, and fully characterizable, preferably under in situ reaction conditions. A range of nanoporous and nanoparticle catalysts, designed, synthesized, characterized, and tested by the authors and their colleagues, that meet most of the stringent demands of sustainable development and responsible (clean) technology is described. Specific examples that are highlighted include: (a) the production of adipic acid (precursor of polyamides and urethanes) without the use of concentrated nitric acid or the production of greenhouse gases such as nitrous oxide; (b) the production of caprolactam (precursor of nylon) without the use of oleum and hydroxylamine sulfate; and (c) the terminal oxyfunctionalization of linear alkanes in air. The topic of biocatalysis and sustainable development is also briefly discussed, and a cautionary note is sounded concerning fast screening methods for the discovery of new inorganic catalysts.


2020 ◽  
Vol 20 (7) ◽  
pp. 4011-4014 ◽  
Author(s):  
Maeum Han ◽  
Jae Keon Kim ◽  
Junyeop Lee ◽  
Hee Kyung An ◽  
Jong Pil Yun ◽  
...  

The proposed study describes the development of a carbon nanotube (CNT)-based gas sensor capable of detecting the presence of hydrogen (H2) gas at room temperature. CNT yarn used in the proposed sensor was fabricated from synthesized CNT arrays. Subsequently, the yarn was treated by means of a simple one-step procedure, called acid treatment, to facilitate removal of impurities from the yarn surface and forming functional species. To verify the proposed sensor’s effectiveness with regard to detection of H2 gas at room temperature, acid-treated CNT and pure yarns were fabricated and tested under identical conditions. Corresponding results demonstrate that compared to the untreated CNT yarn, the acid-treated CNT yarn exhibits higher sensitivity to the presence of H2 gas at room temperature. Additionally, the acid-treated CNT yarn was observed to demonstrate excellent selectivity pertaining to H2 gas.


2013 ◽  
Vol 2013 ◽  
pp. 1-5
Author(s):  
Scott J. Kirkby

Chlorobenzene was reacted with NO2, in the initially acid-free zeolite NaZSM-5, to yield para-chloronitrobenzene exclusively. The precursors were loaded sequentially into self-supporting pellets of the zeolite, contained within a stainless steel cell, from the gas phase. The reaction proceeds spontaneously at room temperature. It is, however, very temperature dependent and effectively ceases at zero degrees Celsius. The reaction was monitored in situ using FT-IR. The active nitrating agent is formed from the partial electron donation by the NO2 to the Na+ cations present in the zeolite lattice. Under the reaction conditions, chlorobenzene is not readily mobile through the pore system; thus, only the molecules adsorbed near a cation site react to form para-chloronitrobenzene.


2020 ◽  
Author(s):  
Cheng Li-Jie ◽  
Zhao Siling ◽  
Neal Mankad

A Cu-catalyzed carbonylative borylation of unactivated alkyl halides has been developed, enabling efficient synthesis of aliphatic potassium acyltrifluoroborates (KATs) in high yields by treating the in-situ formed tetracoordinated acylboron intermediates with aqueous KHF2. A variety of functional groups are tolerated under the mild reaction conditions, and primary, secondary and tertiary alkyl halides are all applicable. In addition, this method also provides facile access to N-methyliminodiacetyl (MIDA) acylboronates as well as α-methylated potassium acyltrifluoroborates in a one-pot manner. Mechanistic studies indicate a radical atom transfer carbonylation (ATC) mechanism to form acyl halide intermediates that are subsequently borylated by (NHC)CuBpin.<br>


1989 ◽  
Vol 35 (1) ◽  
pp. 173-176 ◽  
Author(s):  
P Fossati ◽  
M Ponti ◽  
L Prencipe ◽  
G Tarenghi

Abstract We describe an improved colorimetric method for assays of total and direct bilirubin in serum. Bilirubin reacts with diazotized sulfanilic acid in an acidic medium to form a blue azopigment. Total bilirubin is assayed in the presence of reaction accelerators (caffeine, urea, and citric acid), direct bilirubin in their absence. The azo compound so formed is read at the same wavelength (570 nm) in both assays. A sample blank is run in parallel. Standard curves are linear for total and direct bilirubin concentrations up to 513.0 and 256.5 mumol/L, respectively. The method is characterized by (a) use of the same protocol for both assays, i.e., a one-step procedure with short reaction time (5 min at room temperature), and (b) use of a single working solution, which, refrigerated, is stable for one month. The method is reliable, yields results that compare closely with those of the classical Jendrassik--Gróf method, is suitable for routine use, and lends itself to automation.


2019 ◽  
Author(s):  
Tomas Vojkovsky ◽  
Shubham Deolka ◽  
Saiyyna P. Stepanova ◽  
Michael C. Roy ◽  
Eugene Khaskin

<a>Sulfones and sulfonamides with an α-CH bond can be easily alkylated by aliphatic alcohols to add the carbon skeleton of the alcohol via a one-step, Ru(II) catalyzed redox neutral reaction. The reaction requires a sub-stoichiometric amount of base and produces only water as a byproduct. A number of pharmaceutically relevant functional groups such as piperidine, morpholine, etc. are well tolerated under the reaction conditions to give higher value-added products in one step from widely available substrates. The reaction proceeds through a sulfone carbanion addition to an in-situ generated aldehyde formed via catalytic dehydrogenation and subsequent catalyst mediated replacement of the secondary alcohol by hydrogen.</a>


1992 ◽  
Vol 60 (1) ◽  
pp. 1-3 ◽  
Author(s):  
J. Koch ◽  
J. Mogensen ◽  
S. Pedersen ◽  
H. Fischer ◽  
J. Hindkj&aelig;r ◽  
...  

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