Monday, 11 August 2014

Hemicellulose-derived chemicals: one-step production of furfuryl alcohol from xylose

Hemicellulose-derived chemicals: one-step production of furfuryl alcohol from xylose

 

 

 

 

 

Green Chem., 2014, 16,3942-3950
DOI: 10.1039/C4GC00398E, Paper

*
Corresponding authors
a
Instituto Nacional de Tecnologia/MCTI, Divisão de Catálise e Processos Químicos, Av. Venezuela, 82/518, Centro, Rio de Janeiro, Brazil 
E-mail: marco.fraga@int.gov.br

This study reports an innovative process to obtain furfuryl alcohol from xylose over a dual heterogeneous catalyst system that allows the reaction to occur in a single step. The presence of acid and metal sites is mandatory to promote the dehydration of xylose to furfural and its hydrogenation to furfuryl alcohol. The composition of solvent is decisive in determining the selectivity.
 One-pot production of furfuryl alcohol via xylose dehydration followed by furfural hydrogenation was investigated over a dual catalyst system composed of Pt/SiO2 and sulfated ZrO2 as metal and acid catalysts, respectively. All samples were characterized by XRD, XRF, N2 physisorption, TG-MS and FTIR regarding their most fundamental properties for the studied process. A systematic study is reported on the effects of the reaction temperature, the composition of the binary solvent and the molar ratio between acid and metal sites in the catalyst system. The results revealed the feasibility of the one-step process for furfuryl alcohol synthesis and showed that the occurrence of both acid and metal sites is compulsory in order to promote the dehydration of xylose to furfural and its further hydrogenation to furfuryl alcohol. Selectivity towards furfuryl alcohol was found to be strongly dependent on the solvent, which can inhibit its polymerization to some extent.

Combination of Pd/C and Amberlyst-15 in a single reactor for the acid/hydrogenating catalytic conversion of carbohydrates to 5-hydroxy-2,5-hexanedione

Combination of Pd/C and Amberlyst-15 in a single reactor for the acid/hydrogenating catalytic conversion of carbohydrates to 5-hydroxy-2,5-hexanedione

 

 

 






Green Chem., 2014, Advance Article
DOI: 10.1039/C4GC01158A, Communication
Hide Affiliations
*
Corresponding authors
a
Institut de Chimie des Milieux et Matériaux de Poitiers, ENSIP, Université de Poitiers, 1 rue Marcel Doré, 86022 Poitiers, France 
E-mail: francois.jerome@univ-poitiers.fr
b
Eco-Efficient Products and Processes Laboratory, UMI 3464 CNRS/Solvay, 3966 Jin Du Road, Shanghai 201108, China 
E-mail: floryan.decampo@solvay.com















Here we show that combination of Pd/C and Amberlyst-15 in a single reactor allowed fructose and inulin to be converted to 5-hydroxy-2-5-hexanedione, a valuable chemical platform, in a one-pot process.
http://pubs.rsc.org/en/Content/ArticleLanding/2014/GC/C4GC01158A?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+rss%2FGC+%28RSC+-+Green+Chem.+latest+articles%29#!divAbstract
Here we report an effective cooperation between Pd/C and Amberlyst-15 for the catalytic conversion of fructose and inulin to 5-hydroxymethyl-2,5-hexanedione in a one-pot process.

Sunday, 10 August 2014

Catalyst-free sulfonylation of activated alkenes for highly efficient synthesis of mono-substituted ethyl sulfones in water




Catalyst-free sulfonylation of activated alkenes for highly efficient synthesis of mono-substituted ethyl sulfones in water

Green Chem., 2014, Advance Article
DOI: 10.1039/C4GC00932K, Communication
Yu Yang,a   Lin Tang,a   Sheng Zhang,a   Xuefeng Guo,a  Zhenggen Zhaa and   Zhiyong Wang*a   
 
*
Corresponding authors
a
Hefei National Laboratory for Physical Sciences at Microscale, CAS Key Laboratory of Soft Matter Chemistry & Collaborative Innovation Center of Suzhou Nano Science and Technology, University of Science and Technology of China, Hefei, P. R. China
E-mail: zwang3@ustc.edu.cn;
Fax: (+86) 551-360-3185
Green Chem., 2014, Advance Article

DOI: 10.1039/C4GC00932K
A catalyst-free sulfonylation of activated alkenes developed under mild conditions in water.
 
 
 
 
  
A catalyst-free sulfonylation reaction of activated alkenes with sulfonyl hydrazides was efficiently developed under mild and environmentally benign conditions, in water without any ligand or additive. The reaction gave a range of structurally diverse mono-substituted ethyl sulfones with excellent yields, in which the by-product was nitrogen.

Friday, 1 August 2014

Oleanolic acid spectral data and interpretation

Oleanolic acid spectral data and interpretation


Chemical structure for Oleanolic Acid



Oleanolic acid

Oleanolic acid
(4aS,6aR,6aS,6bR,8aR,10S,12aR,14bS)-10-hydroxy-2,2,6a,6b,9,9,12a-heptamethyl-1,3,4,5,6,6a,7,8,8a,10,11,12,13,14b-tetradecahydropicene-4a-carboxylic acid


see full interpretation, 1H NMR, 13C NMR at

Thursday, 17 July 2014

Bishydrazide to Synthesize oxadiazoles......Important drugs



Bishydrazide to Synthesize oxadiazoles





Drugs containing 1, 3, 4-oxadiazole moiety






http://www.pharmatutor.org/articles/Chemistry-common-synthetic-route-oxadiazole-%20important-heterocyclic-moiety-in-medicinal-chemistry?page=0,5

http://www.pharmatutor.org/articles/Chemistry-common-synthetic-route-oxadiazole-%20important-heterocyclic-moiety-in-medicinal-chemistry?page=0,0Links





Novel 2-amino-5-substituted-1,3,4-oxadiazoles have been synthesized in excellent yields using the synthetic route outlined in Scheme 1. IR, 1H NMR, 13C NMR and mass spectral data are in agreement with the proposed structures of all synthesized compounds. 

Lack of 1H NMR resonances observed with NH and NH2 functions in the1H NMR spectrum of 1a-n proved that ring closure starting from 4 resulted in the formation of 2-amino-1,3,4-oxadiazole ring. 
This was further substantiated by the 13C NMR data of 1 which showed the peaks at 8 170-173 and 145-150 due to C2 and C5 of oxadiazole respectively. The IR spectrum shows 1600-1620 ern1 for (C=N-N=C) and 1063-1073 cm-1 for (C-O-C) in the compounds 1a-1n which confirmed the synthesis of 1,3,4-oxadiazoles.



http://www.scielo.cl/scielo.php?pid=S0717-97072010000100030&script=sci_arttextLinks


1,3,4-oxadiazole is a versatile lead molecule for designing potential bioactive agents. The 1,3,4-oxadiazole derivatives have been found to exhibit diverse biological activities such as hypotensive1 anti-microbial2-4, anti-HIV2-4, anti-fungal5-6 anti-inflammatory7 antimitotic activity8 and muscle relaxant9
It have been found in the líterature study that the methods for synthesis of oxadiazole 1 include bromine oxidation of semicarbazide derivative and the cyclodesulfurization of acylthiosemicarbazide derivatives in the solution using I2/NaOH or 1,3-dicyclohexylcarbodimide (DCC)10-13 as well as mercury(II) acetate (Hg(OAc)2) or yellow mercury(II) oxide HgO14-16 Evans17 synthesized oxadiazole derivatives by rapid parallel synthesis in efficient one-pot preparation using resin-bound reagents. All these methods are usually carried out in various different synthetic steps and require the heating at higher temperature. The handling of these reagents is not only difficult but also very hazardous to environment. The each stage of the reaction including extraction and purification of the producís from the mixture requires great precautions.





EXAMPLE 1 3-(Trifluoromethyl -5,6,7,8-tetrahydrori,2,41triazolor4.3-α1pyrazine, hydrochloride salt (1-4)
Step A: Preparation of bishydrazide (1-1)
Figure imgf000008_0001
H
Hydrazine (20.1 g, 35 wt% in water, 0.22 mol) was mixed with 310 mL of acetonitrile. 31.5 g of ethyl trifluoroacetate (0.22 mol) was added over 60 min. The internal temperature was increased to 25 °C from 14 °C. The resulting solution was aged at 22 - 25 °C for 60 min. The solution was cooled to 7 °C. 17.9 g of 50 wt% aqueous NaOH (0.22 mol) and 25.3 g of chloroacetyl chloride (0.22 mol) were added simultaneously over 130 min at a temperature below 16 °C. When the reaction was complete, the mixture was vacuum distilled to remove water and ethanol at 27 ~ 30 °C and under 26 ~ 27 in Hg vacuum. During the distillation, 720 mL of acetonitrile was added slowly to maintain constant volume (approximately 500 mL). The slurry was filtered to remove sodium chloride. The cake was rinsed with about 100 mL of acetonitrile. Removal of the solvent afforded bis-hydrazide \Λ
(43.2 g, 96.5% yield, 94.4 area% pure by HPLC assay).
1H-NMR (400 MHz, DMSO-dfc): δ 4.2 (s, 2H), 10.7 (s, 1H), and 11.6 (s, 1H) ppm.
13C-NMR (125 MHz, DMSO-_f6): δ 41.0, 116.1 (q, J = 362 Hz), 155.8 (q, J = 50 Hz), and 165.4 ppm.
HPLC conditions: Symmetry 4.6 x 250 mm C18 column; UV detection at 210 nm; mobile phase: 1:1 ACN: H2O (0.1% H3PO ); flow rate: 1 rnL/min; retention time of
1-1: 2.9 min.
Step B: Preparation of 5-(trifluoromethyl)-2-(chloromethyl)- 1.3 ,4-oxadiazole
Figure imgf000009_0001
F3C
Figure imgf000009_0002
Bishydrazide LI from Step A (43.2 g, 0.21 mol) in ACN (82 mL) was cooled to
5 °C. Phosphorus oxychloride (32.2 g, 0.21 mol) was added, maintaining the temperature below 10 °C. The mixture was heated to 80 °C and aged at this temperature for 24 h until HPLC showed less than 2 area% of LI. In a separate vessel, 260 mL of LPAc and 250 mL of water were mixed and cooled to 0 °C. The reaction slurry was charged to the quench keeping the internal temperature below 10 °C. After the addition, the mixture was agitated vigorously for 30 min, the temperature was increased to room temperature and the aqueous layer was cut. The organic layer was then washed with 215 mL of water, 215 mL of 5 wt% aqueous sodium bicarbonate and finally 215 mL of 20 wt% aqueous brine solution. HPLC assay yield after work up was 86-92%. Volatiles were removed by distillation at 75-80 mm Hg, 55 °C to afford an oil which could be used directly in Step C without further purification. Otherwise the product can be purified by distillation to afford L2 in 70-80% yield. 1H-NMR (400 MHz, CDC13): 04.8 (s, 2H) ppm.
13C-NMR (125 MHz, CDC13): δ 32.1, 115.8 (q, J = 337 Hz), 156.2 (q, J = 50 Hz), and 164.4 ppm. HPLC conditions: Symmetry 4.6 x 250 mm C18 column; UV detection at 210 nm; mobile phase: 1:1 ACN: H2O (0.1% H3PO4); flow rate: 1 rnL/min; retention time of 1-2: 8.8 min.




Synthesis of 1,3,4-oxadiazoles

Recent Literature

A direct access to symmetrical and unsymmetrical 2,5-disubstituted [1,3,4]-oxadiazoles has been accomplished through an imine C-H functionalization of N-arylidenearoylhydrazide using a catalytic quantity of Cu(OTf)2. These reactions can be performed in air atmosphere and moisture making it exceptionally practical for application in organic synthesis.
S. Guin, T. Ghosh, S. K. Rout, A. Banerjee, B. K. Patel, Org. Lett.201113, 5976-5979.




A facile and general protocol for the preparation of 2-amino-1,3,4-oxadiazoles relies on a tosyl chloride/pyridine-mediated cyclization of thiosemicarbazides that consistently outperforms the analogous semicarbazide cyclizations. Various 5-alkyl- and 5-aryl-2-amino-1,3,4-oxadiazoles have been prepared in good yields.
S. J. Dolman, F. Gosselin, P. D. O'Shea, I. W. Davies, J. Org. Chem.200671, 9548-9551.





An oxidative desulfurization approach enables the construction of oxadiazole and thiadiazole heterocycles in the presence of iodobenzene and Oxone. The use of iodobenzene and the inexpensive readily available oxidant Oxone makes the reaction system simple and versatile for desulfurization.
K. N. Patel, N. C. Jadhav, P. B. Jagadhane, V. N. Telvekar, Synlett201223, 1970-1972.




The reaction of a thiosemicarbazide intermediate with EDC·HCl in DMSO or p-TsCl, triethylamine in N-methyl-2-pyrrolidone gives the corresponding 2-amino-1,3,4-oxadiazoles and 2-amino-1,3,4-thiadiazoles through regioselcective cyclization processes.
S.-J. Yang, S.-H. Lee, H.-J. Kwak, Y.-D. Gong, J. Org. Chem.201378, 438-444.




N-Isocyaniminotriphenylphosphorane, aldehydes, and benzoic acids undergo a one-pot, three-component reaction under mild conditions to afford 2-aryl-5-hydroxyalkyl-1,3,4-oxadiazoles in good yields.
M. Adib, M. R. Kesheh, S. Ansari, H. R. Bijanzadeh, Synlett2009, 1575-1578.





Symmetric and unsymmetric 1,3,4-oxadiazoles were synthesized in situ from hydrazine hydrate and the corresponding 2-acyl-4,5-dichloropyridazin-3-ones as acylating agents in polyphosphoric acid (PPA) or BF3·OEt2 in excellent yields.
Y.-D. Park, J.-J. Kim, H.-A. Chung, D.-H. Kweon, S.-D. Cho, S.-G. Lee, Y.-J. Yoon, Synthesis2003, 560-564.





A simple and straightforward method for the direct carboxylation of aromatic heterocylces such as oxazoles, thiazoles, and oxadiazoles using CO2 as the C1 source requires no metal catalyst and only Cs2CO3 as the base. A good functional group tolerance is achieved.
O. Vechorkin, N. Hirt, X. Hu, Org. Lett.201012, 3567-3569.





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ANTHONY MELVIN CRASTO
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DR ANTHONY MELVIN CRASTO Ph.D , Born in Mumbai in 1964 and graduated from Mumbai University, Completed his  PhD from ICT ,1991,  Mumbai, India in Organic chemistry, The thesis topic was Synthesis of Novel Pyrethroid Analogues, Currently he is working with GLENMARK- GENERICS LTD, Research centre as Principal Scientist, Process Research (bulk actives) at Mahape, Navi Mumbai, India. Prior to joining Glenmark, he worked with major multinationals like Hoechst Marion Roussel, now Sanofi Aventis,  & Searle India ltd, now Rpg lifesciences, etc. He has worked in Basic research, Neutraceuticals, Natural products, Flavors, Fragrances, Pheromones, Vet Drugs, Drugs, formulation, GMP etc. He has total 25 yrs exp in this field, he is now helping millions, has million hits on google on all organic chemistry websites.His New Drug Approvals ,  Green Chemistry International,  Eurekamoments in Organic Chemistry ,   WIX BLOG WORLD DRUG TRACKER
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Wednesday, 16 July 2014

An unsaturated hydrogen bonded network generated from three-fold symmetric carbamates



CrystEngComm, 2014, 16,7176-7179
DOI: 10.1039/C4CE00363B, Communication
Zijun Wang, Joseph Lee, Casey Oian, Xiaodong Hou, Zhihan Wang, Angel Ugrinov, Rajiv K. Singh, Erin Wysocki, Qianli R. Chu
A new crystalline sheet spontaneously assembled under mild conditions from tri-carbamates. The discovery of the unsaturated hydrogen bonded sheet further demonstrated the variety and adaptability of the sheet structures.


read at

 http://pubs.rsc.org/en/Content/ArticleLanding/2014/CE/C4CE00363B?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+rss%2FCE+%28RSC+-+CrystEngComm+latest+articles%29#!divAbstract

A new hydrogen bonded network self-assembles under mild conditions from benzene-1,3,5-triyl tris(butyl carbamate) or benzene-1,3,5-triyl tris(hexyl carbamate). One of the carbonyl groups in the tri-carbamate does not form a C[double bond, length as m-dash]OH–N hydrogen bond in the sheet-like structure. Although the building blocks only differ in the carbon numbers of the side chains, this 2D unsaturated hydrogen bonded network is different from the saturated one self-assembled from benzene-1,3,5-triyl tris(propyl carbamate). The lamellar structures were studied and compared by using their melting points, NMR and FT-IR spectroscopy, and single crystal X-ray diffraction.