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Sunday, 31 August 2014

7,7-dichlorobicyclo[4.1.0]heptane (7,7-dichloronorcarane

7,7-dichlorobicyclo[4.1.0]heptane (7,7-dichloronorcarane

reacts to
7,7-Dichlorobicyclo[4.1.0]heptane+Hydrogen chloride

Synthesis of 7,7-dichlorobicyclo[4.1.0]heptane (7,7-dichloronorcarane) from cyclohexene

Reaction type:addition to alkenes, elimination, cycloaddition
Substance classes:alkene, carbene, chloroalkane
Techniques:stirring with magnetic stir bar, adding dropwise with an addition funnel, distilling under reduced pressure, evaporating with rotary evaporator, shaking out, extracting, filtering, use of an ice cooling bath, heating with oil bath

Instruction (batch scale 100 mmol)
100 mL three neck round bottom flask, reflux condenser, addition funnel with pressure
balance, heatable magnetic stirrer, magnetic stir bar, thermometer for inside of the flask,
separating funnel, destillation apparatus, rotary evaporator, oil bath, ice bath, vacuum pump
cyclohexene (bp 83 °C) 8.21 g (10.1 mL, 100 mmol)
chloroform (bp 61 °C) 48.0 g (32.7 mL, 400 mmol)
sodium hydroxide 16.0 g (400 mmol)
tri-n-propylamine (bp 156 °C) 0.14 g (0.19 mL, 1.0 mmol)
water 16 mL
ethanol (bp 78 °C) 1 mL
n-pentane (bp 36 °C) 120 mL
sodium sulfate for drying about 5 g
sodium chloride about 18 g
Into a 100 mL three neck round bottom flask equipped with a reflux condenser addition
funnel, thermometer for measuring the inside temperature and magnetic stir bar, 8.21 g
(10.1 mL, 100 mmol) cyclohexene 0.14 g (0.19 mL, 1.0 mmol) tri-n-propylamine, 48.0 g
(32.7 mL, 400 mmol) chloroform and 1 mL ethanol is added. The mixture is cooled to 0 °C
with an ice bath, then under stirring and further cooling in the ice bath a solution of 16.0 g
(400 mmol) sodium hydroxide in 16 mL water is added through an addition funnel. The
mixture should be stirred vigourously during the next 20 minutes at 0 °C. After this time the
mixture is further stirred during 1 hour at room temperature and 3 hours at 50 °C.
Work up
Chloroform is evaporated with a rotary evaporator, then the residue is transferred with about
50 mL water and 30 mL n-pentane into a separating funnel. The organic phase is separated,
the aqueous phase is further extracted three times with 30 mL pentane. If an emulsion is
formed the aqueous phase is saturated with NaCl. The combined organic phases are dried over
sodium sulfate. The solution is filtered from sodium sulfate and the solvent is evaporated with
a rotary evaporator, yielding a nearly colourless liquid as crude product. The crude yield is
14.6 g. The crude product is distilled under reduced pressure.
Yield: 13.6 g (82.3 mmol, 82%), colourless liquid; bp 77 °C (11 hPa)

Operating scheme

Operating schemeOperating scheme


Batch scale:0.01 mol0.1 mol1 molCyclohexene

two-necked flask 10 mLtwo-necked flask 10 mLreflux condenserreflux condenser
heatable magnetic stirrer with magnetic stir barheatable magnetic stirrer with magnetic stir barthermometerthermometer
graduated pipettegraduated pipetteseparating funnelseparating funnel
microdistillation apparatusmicrodistillation apparatusrotary evaporatorrotary evaporator
oil bathoil bathice bathice bath
vacuum pumpvacuum pump


pure product chromatogram

GC: pure productcolumnSE-54, L= 25 m, ID 0.32 mm, DF 0.25 µm (Macherey & Nagel)inletGerstel KAS, injector: 250°C, split injection 1:20, 0.15 µLcarrier gasN2, pre-column pressure 62 kPa, 1.04 mL/minoven80 °C (1 min), 10 °C/min --> 250 °C (30 min)detectorFID, 275 °Cintegrationpercent concentration calculated from relative peak area


1H-NMR: 7,7-Dichlorobicyclo[4.1.0]heptane
500 MHz, CDCl3
delta [ppm]mult.atomsassignment
1.12-1.36m4 HC4-H, C5-H
1.61-1.71m4 HC3-H, C6-H
1.88-1.98m2 HC1-H, C2-H
7.26s1 HCHCl3


3C-NMR: 7,7-Dichlorobicyclo[4.1.0]heptane
125 MHz, CDCl3
delta [ppm]assignment
18.9C4, C5
20.2C3, C6
25.8C2, C1

IR: 7,7-Dichlorobicyclo[4.1.0]heptane
[Film, T%, cm-1]
2944, 2855aliph. C-H valence
796C-Cl valence


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Sunday, 24 August 2014

ENDO EXO STORY.......cis-norborene-5,6-endo-dicarboxylic anhydride

ENDO EXO STORY.......cis-norborene-5,6-endo-dicarboxylic anhydride


You will react cyclopentadiene with maleic anhydride to form the Diels-Alder product below. This Diels-Alder reaction produces almost solely the endo isomer upon reaction at ambient temperature.


The preference for endo–stereochemistry is “observed” in most Diels-Alder reactions. The fact that the more hindered endo product is formed puzzled scientists until Woodward, Hoffmann, and Fukui used molecular orbital theory to explain that overlap of the p orbitals on the substituents on the dienophile with p orbitals on the diene is favorable, helping to bring the two molecules together.

Hoffmann and Fukui shared the 1981 Nobel Prize in chemistry for their molecular orbital explanation of this and other organic reactions. In the illustration below, notice the favorable overlap (matching light or dark lobes) of the diene and the substituent on the dienophile in the formation of the endo product:


Oftentimes, even though the endo product is formed initially, an exo isomer will be isolated from a Diels-Alder reaction. This occurs because the exo isomer, having less steric strain than the Endo , is more stable, and because the Diels-Alder reaction is often reversible under the reaction conditions. In a reversible reaction, the product is formed, reverts to starting material, and forms again many times before being isolated.

The more stable the product, the less likely it will be to revert to the starting material. The isolation of an exo product from a Diels-Alder reaction is an example of an important concept: thermodynamic vs kinetic control of product composition. The first formed product in a reaction is called the kinetic product. If the reaction is not reversible under the conditions used, the kinetic product will be isolated. However, if the first formed product is not the most stable product and the reaction is reversible under the conditions used, then the most stable product, called the thermodynamic product, will often be isolated.

The NMR spectrum of cis-5-norbornene-2,3-endo-dicarboxylic anhydride is given below:

Cis-Norbornene-5,6-endo-dicarboxylic anhydride 
Cyclopentadiene was previously prepared through the cracking of dicyclopentadiene and kept under cold conditions.  In a 25 mL Erlenmeyer flask, maleic anhydride (1.02 g, 10.4 mmol) and ethyl acetate (4.0 mL) were combined, swirled, and slightly heated until completely dissolved.  To the mixture, ligroin (4 mL) was added and mixed thoroughly until dissolved.  Finally, cyclopentadiene (1 mL, 11.9 mmol) was added to the mixture and mixed extensively.  The reaction was cooled to room temperature and placed into an ice bath until crystallized.  The crystals were isolated through filtration in a Hirsch funnel.  The product had the following properties: 0.47 g (27.6% yield) mp: 163-164 °C (lit: 164 °C).  1H NMR (CDCl3, 300 MHz) δ: 6.30 (dd, J=1.8 Hz, 2H), 3.57 (dd, J=7.0 Hz, 2H), 3.45 (m, 2H), 1.78 (dt, J=9.0,1.8 Hz, 1H), 1.59 (m, 1H) ppm.  13C NMR (CDCl3, 75Hz) δ: 171.3, 135.5, 52.7, 47.1, 46.1 ppm.  IR 2982 (m), 1840 (s), 1767 (s), 1089 (m) cm-1.

Reaction Mechanism The scheme below depicts the concerted mechanism of the Diels-Alder reaction of cyclopentadiene and maleic anhydride to formcis-Norbornene-5,6-endo-dicarboxylic anhydride.

diels-alder reaction

Results and Discussion 
When combining the reagents, a cloudy mixture was produced and problems arose in the attempt to completely dissolve the mixture.  After heating for about 10 minutes and magnetically stirring, tiny solids still remained. The undissolved solids were removed form the hot solution by filtration and once they cooled, white crystals began to form. Regarding the specific reaction between cyclopentadiene and maleic anhydride, the endo isomer, the kinetic product, was formed because the experiment was directed under mild conditions.   The exo isomer is the thermodynamic product because it is more stable.3
A total of 0.47 g of the product was collected; a yield of 27.6%. The melting point was in the range of 163-164 °C which indicates the absence of impurities because the known melting point of the product is 164 °C.
Cis-Norbornene-5-6-endo-dicarboxylic anhydride

The 1H NMR spectrum of the product revealed a peak in the alkene range at 6.30 ppm, H-2 and H-3 (Figure 1).  In addition, it exhibited two peaks at 3.57 and 3.45 ppm because of the proximity of H-1, H-4, H-5, and H-6 to an electronegative atom, oxygen.  Finally, two peaks at 1.78 and 1.59 ppm corresponded to the sp3 hydrogens, Hb and Ha, respectively.  Impurities that appeared included ethyl acetate at 4.03, 2.03, and 1.31 ppm as well as acetone at 2.16 ppm.
Regarding the 13C NMR, a peak appeared at 171.3 ppm, accounting for the presence of two carbonyl functional groups, represented by C-7 and C-8 in Figure 1.  The alkene carbons, C-2 and C-3, exhibited a peak at 135.5 ppm, while the sp3 carbons close to oxygen, C-5 and C-6, displayed a peak at 52.7 ppm.  Finally, peaks at 46.1 and 47.1 ppm accounted for the sp3 carbons, C-1 and C-4, and C-9.  Impurities of ethyl acetate appeared at 46.6, 25.8, and 21.0 ppm accompanied with acetone at 30.9 ppm.
The IR spectrum revealed a peak at 2982 cm-1 representing the C-H stretches.  A peak at 1840 cm-1 accounted for the carbonyl functional group, while a peak at 1767 cm-1 accounted for the alkene bond.  A peak at 1089 cm-1 represented the carbon-oxygen functional group.
In order to distinguish between the two possible isomers, properties such as melting point and spectroscopy data were analyzed.  The exo product possessed a melting point in the range of 140-145 °C which is significantly lower than the endo product.  The observed melting point in this experiment supported the production of the endo isomer. 
The 1H NMR spectum exhibited a doublet of doublets at 3.57 ppm for the endo isomer.  The exo isomer would possess a triplet around 3.50 ppm due to the difference in dihedral angle between the hydrogen molecules of H-1 and H-4, and H-5 and H-6 (Figure 1).  A peak at 3.00 ppm would appear in the exo isomer spectra as opposed to a peak at 3.60 ppm as shown in the observed endo product.3 This is because of the interaction and coupling with the H-5 and H-6, as displayed in Figure 1.

Through the Diels-Alder reaction, 27.6% yield of cis-Norbornene-5,6-endo-dicarboxylic anhydride was produced. The distinction of the presence of the endo isomer was proven by analyzing physical properties of both possible isomers.
Martin, J.; Hill, R.; Chem Rev, 196161, 537-562.
2 Pavia, L; Lampman, G; Kriz, G; Engel, R. A Small Scale Approach to Organic Laboratory   Techniques, 2011, 400-409.
3 Myers, K.; Rosark, J. Diels-Alder Synthesis, 2004, 259-265.


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Tuesday, 12 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
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
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
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.
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.


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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
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.