Saturday, 19 April 2014

Au catalyzed synthesis of benzimidazoles from 2-nitroanilines and CO2/H2




Green Chem., 2014, Advance Article
DOI: 10.1039/C4GC00153B, Paper
Leiduan Hao, Yanfei Zhao, Bo Yu, Hongye Zhang, Huanjun Xu, Zhimin Liu
The gold-catalyzed synthesis of benzimidazoles from 2-nitroanilines and CO2 in the presence of H2 was reported, and a series of benzimidazoles were obtained under relatively mild conditions.


The gold-catalyzed synthesis of benzimidazoles from 2-nitroanilines and CO2 in the presence of
 H2 was reported, and a series of benzimidazoles were obtained under relatively mild conditions. 
Several supported Au catalysts including Au/TiO2, Au/Al2O3, Au/ZnO, Au/polyurea and Au/hydrotalcite
 were examined for the synthesis of benzimidazole from the reaction of 2-nitroaniline with CO2 and H2
among which Au/TiO2 displayed the best performance. The reaction mechanism was investigated, 
and it was found that the production of benzimidazole underwent the formation of o-phenylenediamine 
via the hydrogenation of 2-nitroaniline, followed by the cyclization of o-phenylenediamine with CO2 and H2
This work provides a CO2-involved route for the synthesis of benzimidazoles, 
which may widen the applications of CO2 in the chemical synthesis.

ORGANIC SPECTROSCOPY INTERNATIONAL: Ethyl 4-nitrobenzoate NMR

ORGANIC SPECTROSCOPY INTERNATIONAL: Ethyl 4-nitrobenzoate NMR:



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Monday, 14 April 2014

Natural sweeteners maple syrup, agave, and honey are complex mixtures with bioactive components that might confer health benefits

Pass the syrup! Maple syrup is a complex mixture of compounds, incuding bioactive components that might confer health benefits.
http://cen.acs.org/articles/92/i15/ACS-Meeting-News-Looking-Beyond.html

Maple syrup, agave, and honey are well-known for their roles as sweeteners. As such, their primary constituents are simple sugars such as sucrose and fructose. But scientists exploring the composition of these sweeteners are finding them to be surprisingly complicated.
These sweet mixtures contain many other classes of compounds, especially polyphenols, some of which may have bioactivity that imparts health benefits. Scientists hope to identify the beneficial compounds and eventually increase their concentration in sweeteners, so sweets can be more than just treats. Researchers described their latest findings in a symposium sponsored by the Division of Agricultural & Food Chemistry at the American Chemical Society national meeting held last month in Dallas.
Maple syrup is produced from sap of certain maple species, especially the sugar maple, Acer saccharum, which is native to eastern North America. Maple syrup is produced only in the U.S. and Canada, and about 80% of the world’s supply comes from Quebec.

Saturday, 5 April 2014

Ethyl acetoacetate 乙酰乙酸乙酯 teaches you Organic spectroscopy... brush up?????

read at
http://orgspectroscopyint.blogspot.in/2014/04/ethyl-acetoacetate-teaches-you-organic.html
Ethyl acetoacetate
Ethyl 3-oxobutanoate
Acetoacetic acid ethyl ester
Ethyl acetylacetate
3-Oxobutanoic acid ethyl ester



Ethyl acetoacetate is produced industrially by treatment of diketene with ethanol.
The preparation of ethyl acetoacetate is a classic laboratory procedure.[2] It is prepared via the Claisen condensation of ethyl acetate. Two moles of ethyl acetate condense to form one mole each of ethyl acetoacetate and ethanol.

Preparation of ethyl acetoacetate.









Structure: structure

IUPAC Name: ethyl 3-oxobutanoate (ethyl acetoacetate)

Analysis: C6H10O3: MW = 130.14


The molecule contains an oxygen, and from the analysis, contains two double bonds, carbonyls or rings.
The mass spectrum displays a molecular ion and the base peak represents the formation of the acylium ion, indicating the presence of a methyl adjacent to a carbonyl. The presence of an m-45 peak strongly suggests the presence of an ethoxy group.
The 13C spectrum contains six peaks, indicating that all carbons are unique. The quartets at  14 and 24 represent relatively simple methyl groups; the triplets at  59 and 47 represent a CH2 groups bonded to mildly electronegative groups; the singlets at  207 and 172 are in the carbonyl region, and most likely a ketone or aldehyde ( 207) and an ester ( 172).
The proton NMR shows evidence for an ethyl group and isolated CH2 and CH3 groups. The methylene of the ethyl group must be next to an electronegative atom (most likely oxygen) suggesting an -OCH2CH3 group. The isolated CH2 must also be flanked by mildly electronegative groups, and the isolated CH3 is in the region often observed for methyls adjacent to carbonyls.
The IR is consistent with a simple saturated hydrocarbon, possibly containing two carbonyls (based on the side peak at  1670 cm-1). The minor peak at 3400 cm-1 is too small to be an -OH.
The simplest structure which is consistent with all of these data would be a dicarbonyl compound containing an ethoxy residue and a methyl ketone (based on the presence of the acylium ion in the MS).
http://orgspectroscopyint.blogspot.in/2014/04/ethyl-acetoacetate-teaches-you-organic.html

......................

1H NMR
NMR Spectrum
The proton NMR has a quartet coupled to a triplet, indicative of an ethyl group. The CH2 must be adjacent to an electron withdrawing group since it is shifted to  4.1. The two singlets at  2.2 and 3.2 suggest isolated CH2 and CH3 groups and the CH2 must be adjacent to one or more electronegative groups.

http://orgspectroscopyint.blogspot.in/2014/04/ethyl-acetoacetate-teaches-you-organic.html



http://orgspectroscopyint.blogspot.in/2014/04/ethyl-acetoacetate-teaches-you-organic.html
................................................................
13C NMR
13C NMR Assignments: C-13 assignments
13C NMR Data: q-13.6; q-24.2; t-59.2; t-46.6; s-172.0; s-207.1 
The 13C spectrum contains six peaks, indicating that all carbons are unique. The quartets at  14 and 24 represent relatively simple methyl groups; the triplets at  59 and 47 represent a CH2 groups bonded to mildly electronegative groups; the singlets at  207 and 172 are in the carbonyl region, and most likely a ketone or aldehyde ( 207) and an ester ( 172).




spectrum for Ethyl acetoacetate






ethyl acetoacetate CH3COCH2COOCH2CH3

................................

MASS SPECTROSCOPY
Mass Spectrum



Mass Spectrum Fragments: C-13 assignments
The mass spectrum consists of a molecular ion at 130, an m-15 peak at 115, which is consistent with loss of a CH3 group, an m-43 peak (loss of acylium), an m-45 peak (loss of CH3CH2O-), and a base peak at m-43(m/e = 43) which suggests the formation of an acylium ion (CH3-CO). The spectrum is consistent with a molecule which can lose methyl or ethoxy radicals, or can undergo fragmentation to form the acylium radical cation.


...............................

IR

3400-3200 cm-1: no OH peak (too small) 3100 cm-1: no significant peak, suggesting no unsaturated CH 2900 cm-1: strong peak suggesting saturated CH 2200 cm-1: no unsymmetrical triple bonds 1710 cm-1: strong carbonyl with a second peak at 1670 cm-1, suggesting a the possibility of two carbonyls 1600 cm-1: no significant peaks, suggesting no carbon-carbon double bonds




http://orgspectroscopyint.blogspot.in/2014/04/ethyl-acetoacetate-teaches-you-organic.html




2D [1H,1H]-TOCSY


spectrum for Ethyl acetoacetate

spectrum for Ethyl acetoacetate1D DEPT135





spectrum for Ethyl acetoacetate2D [1H,13C]-HSQC



spectrum for Ethyl acetoacetate2D [1H,13C]-HMBC





spectrum for Ethyl acetoacetate2D [1H,1H]-COSY


spectrum for Ethyl acetoacetate2D [1H,13C]-HMQC

http://orgspectroscopyint.blogspot.in/2014/04/ethyl-acetoacetate-teaches-you-organic.html

Monday, 24 March 2014

A solution to fluoronium riddle

fluoronium
The presence of a symmetrical fluoronium ion is confirmed by the 1:1 mixture of reaction products

The first evidence for hypervalent fluorine cations, or fluoronium ions, in solution has been found by US chemists. The research lays the foundations for characterising fluoronium ions – where the fluorine has two bonds and a formal positive charge – directly by spectroscopy and improving our understanding of fluorine’s interactions in organic chemistry
 

Saturday, 15 March 2014

An efficient Cu(II)-bis(oxazoline)-based polymer immobilised ionic liquid phase catalyst for asymmetric carbon-carbon bond formation

An efficient Cu(II)-bis(oxazoline)-based polymer immobilised ionic liquid phase catalyst for asymmetric carbon-carbon bond formation

Green Chem., 2014, 16,1470-1479
DOI: 10.1039/C3GC41378K, Paper
Simon Doherty, Julian G. Knight, Jack R. Ellison, Peter Goodrich, Leanne Hall, Christopher Hardacre, Mark J. Muldoon, Soomin Park, Ana Ribeiro, Carlos Alberto Nieto de Castro, Maria Jose Lourenco, Paul Davey
Asymmetric carbon-carbon bond forming reactions were catalysed by heterogeneous copper(II)-bis(oxazoline)-based PIILP systems.


The asymmetric Diels–Alder reaction between N-acryloyloxazolidinone and cyclopentadiene and the Mukaiyama-aldol reaction between methylpyruvate and 1-phenyl-1-trimethylsilyloxyethene have been catalysed by heterogeneous copper(II)-bis(oxazoline)-based polymer immobilised ionic liquid phase (PIILP) systems generated from a range of linear and cross linked ionic polymers. In both reactions selectivity and ee were strongly influenced by the choice of polymer. A comparison of the performance of a range of Cu(II)-bis(oxazoline)-PIILP catalyst systems against analogous supported ionic liquid phase (SILP) heterogeneous catalysts as well as their homogeneous counterparts has been undertaken and their relative merits evaluated.

Free Download Analysis and Purification Methods in Combinatorial Chemistry

Free Download Analysis and Purification Methods in Combinatorial Chemistry edited by Bing Yan


http://chemistry.com.pk/books/analysis-and-purification-methods-in-combinatorial-chemistry/
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Muhammad Hasnain

Founder at Chemistry.Com.Pk
is the founder and author at Chemistry.Com.Pk. He did M.Sc in organic chemistry. Currently he is doing M.Phil leading to Ph.D in chemistry from Department of chemistry, Federal Urdu University of Arts, Sciences and Technology, Karachi. He loves to write about chemistry.