Valorization of glycerol 1,2-carbonate as a precursor for the development of new synthons in organic chemistry

Article abstract of DOI:10.1039/c2gc35678c

Conjugate addition reactions are efficiently performed by a very simple electrochemical method using nickel complexes as catalysts. In this paper, we reported a new method for the valorization of glycerol 1,2-carbonate. Firstly, we prepared the activated glycerol 1,2-carbonate derivatives (halogen or pseudo-halide derivatives), and secondly applied these halogen derivatives in coupling reactions by electrochemical methods with organic compounds and environment-friendly solvent (propylene carbonate). To our knowledge, this is the first report of creation of carbon-carbon bonds on the glycerol 1,2-carbonate and of the synthesis of these compounds.

Full text of DOI:10.1039/c2gc35678c

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PAPER
Valorization of glycerol 1,2-carbonate as a precursor for the development of
new synthons in organic chemistry
Julia Bensemhoun* and Sylvie Condon
Received 3rd May 2012, Accepted 29th June 2012
DOI: 10.1039/c2gc35678c
Conjugate addition reactions are efficiently performed by a very simple electrochemical method using
nickel complexes as catalysts. In this paper, we reported a new method for the valorization of glycerol
1
,2-carbonate. Firstly, we prepared the activated glycerol 1,2-carbonate derivatives (halogen or pseudo-
halide derivatives), and secondly applied these halogen derivatives in coupling reactions by
electrochemical methods with organic compounds and environment-friendly solvent (propylene
carbonate). To our knowledge, this is the first report of creation of carbon–carbon bonds on the glycerol
1
,2-carbonate and of the synthesis of these compounds.
1. Introduction
have shown the polymorphic reactivity of activated glycerol 1,2-
14,17
carbonate in the presence of nucleophiles.
This compound
For several years, the manufacturing of raw materials resulted
from chemicals obtained mainly from fossil resources, which are
these days in the process of exhaustion. Moreover, these raw
materials present a major inconvenience: their very slow bio-
degradation. Consequently, at the moment, their repercussions on
the environment remain an increasing preoccupation. These last
may be also used as a protic solvent, and in cosmetic and
pharmaceutical preparations.
18–21
Modern organic chemistry has a real interest in being more
environment-friendly. Within this context, electrochemistry can
appear as a useful tool since electrons are cheap, clean and
readily available reagents, whose concentration and activity are
easily controlled. Significant progress has been made, notably in
electroreduction, thus providing simple and efficient method-
ologies. Consequently, we report in this paper our preliminary
results devoted to the creation of carbon–carbon bonds from
halogenated or pseudo-halogenated glycerol 1,2-carbonate
derivatives and electron deficient olefins based on an electro-
1
,2
years, the use of renewable feedstocks has presented a major
interest in particular in the chemical industry. Among these
renewable resources, the valorization of glycerol, which is the
main co-product of the industry of vegetable oils (especially bio-
diesel) and broadly available at low prices, is a crucial challenge.
Therefore, it is not surprising that much effort has been devoted
3
–5
22,23
to converting glycerol into high value-added chemicals.
chemical process developed some years ago in our laboratory.
Indeed, chemists have become interested more and more in
glycerol and in its by-products, which are synthesis intermedi-
ates, for the preparation of a large number of compounds via oxi-
Another important point of our work consists of replacing
organic solvents by more environment-friendly solvents. To our
knowledge, this is the first example of creation of carbon–carbon
bonds on the glycerol 1,2-carbonate.
6
7
8
dation,
etherification,
esterification, transesterification,
polymerisation, etc.
In this context, our attention is focused on the development of
new processes for the transformation and the valorization of gly-
cerol and more particularly, due to its low toxicity, the ready
2
. Results and discussion
In this work, we focused on the activation of halogen or pseudo-
halide derivatives of glycerol 1,2-carbonate mediated by nickel
catalysis in conjunction with a consumable anode process, and
then on their reaction with electrodeficient olefins. Firstly, we
prepared the activated glycerol 1,2-carbonate derivatives (2–5) in
order to examine their reactivity in electrochemical conjugate
addition, and secondly applied these halogen derivatives in
coupling reactions (Fig. 1).
9,10
accessibility
of glycerol 1,2-carbonate, an inexpensive com-
pound, which has considerable potential for different transform-
ations in fine chemistry, in order to be used as a precursor for the
11–14
development of new synthons in organic chemistry.
Indeed,
the presence of a cyclic carbonate group along with a primary
hydroxylmethyl group implies that the molecule may react with
1
0,15
aldehydes, anhydrides, and diamines
in order to form ester,
1
6
ether, enol or urethane linkages. Moreover, Rousseau et al.
2
.1. Formation of pseudo-halogen and halogen glycerol 1,2-
carbonate
Equipe Electrochimie et Synthèse Organique, Institut de Chimie et des
Matériaux Paris-Est, 2-5 rue Henri Dunant, 94320 Thiais, France.
E-mail: julia.bens@gmail.com; Fax: +33 149781148;
Tel: +33 149781126
24
As described in the literature, the primary hydroxyl group of
glycerol 1,2-carbonate 1 was activated by tosylation in order to
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Fig. 1 Creation of carbon–carbon bonds.
Fig. 4 Creation of carbon–carbon bonds between halogen aryls and
activated olefins.
obtain compound 2 in 98% yield. Because of its accessibility
and versatility, 3-O-tosyl glycerol 1,2-carbonate 2 was first pre-
pared as an intermediate to get halides 3, 4 (I, Br) and azide 5
derivatives (Fig. 2).
The compound 2 reacted with an excess of tetra-n-butylammo-
nium bromide or iodide in anhydrous acetone leading to com-
pounds 3 and 4 with 90% yield (Fig. 2). This reaction proved to
be the most efficient compared to the use of sodium iodide.
Moreover, the excess of tetra-n-butylammonium bromide or
iodide can be recycled.
Fig. 5 Creation of carbon–carbon bonds from activated glycerol 1,2-
carbonate.
Compound 5 (Fig. 2) was prepared as described in the litera-
ture but the purification method is different.
However, to this day, activation of alkyl halides has not been
achieved.
1
7
The first attempt has been realized between iodide glycerol
1
,2-carbonate and various electrodeficient olefins such as
methylvinylacetone (MVK), butyl acrylate (ABu) and acrylo-
nitrile (ACN) (Fig. 5).
The conjugate addition reactions were conducted in an undi-
vided cell fitted with an iron rod as the anode and a nickel grid
as the cathode, under Ar, in commercial solvents used without
purification. The first step of this reaction is the ionic conduc-
tivity which is ensured by employing NBu Br and NBu I as sup-
4
4
porting electrolytes. A short pre-electrolysis was conducted at
room temperature, leading to an improvement in faradic and
chemical yields as well as the oxidation of the iron anode along
with the reduction of 1,2-dibromoethane in DMF–pyridine
Fig. 2 Formation of tosylated, halides and azide glycerol 1,2-
carbonate.
(9 : 1) prior to the electrolysis run at 76 °C under a constant
current intensity of 0.2 A, until full consumption of the alkyl
halide. The postulated reaction mechanism (Fig. 6) includes (i)
(
0)
2
.2. Creation of carbon–carbon bonds by indirect electrolysis
the electrochemical reduction of NiBr into Ni which is stabil-
2
ized in the solution by complexation to weak ligands (pyridine)
along with the release of iron ions from the anodic oxidation, (ii)
the oxidative addition of the alkyl halide to Ni , (iii) the inser-
In the case of indirect electrolysis, where the species reduced at
the cathode is a catalytic precursor, we generate the catalyst in
solution. The principle is described in Fig. 3.
(0)
tion of the activated olefin into an R–Ni bond, (iv) iron ions
released by the oxidation of the anode may undergo a transmetal-
lation reaction, and this could explain the positive effect of both
the use of iron as the anode and the need for the pre-electrolysis
The reported previous work on the conjugate addition reaction
by nickel catalysis associated with the consumable anode
process developed in our laboratory is characterized by its sim-
plicity and its high functional compatibility to the reaction.
Indeed, in order to create carbon–carbon bonds, our first investi-
gation on this reaction was studied with various aryl halides and
22
to optimize the process.
The first attempt led respectively to compounds 6 (55%),
7
(50%) and 8 (45%) (Fig. 5).
22
electrodeficient or electrodonator groups which are tolerated. It
has also been demonstrated that this reaction is regioselective
and compatible with the presence of functional groups (CN, CO)
In order to improve these yields, some parameters, such as the
temperature, nickel quantity as well as activated olefin amounts,
were modified. The best results were obtained using the follow-
ing parameters: T = 76 °C, NiBr , H O (20%), DMF–pyridine
(Fig. 4).
2
2
(9 : 1), 2.7 equiv. activated olefins leading to yields of about
7
5%.
Under these reaction conditions, other derivatives of glycerol
,2-carbonate bearing an active group were tested on these same
1
electrodeficient olefins (Fig. 5) and the results are reported in
Table 1.
Table 1 shows that good results were as well obtained
with iodide, bromide or azide. It is worth noting that the
Fig. 3 Principle of the indirect electrolysis reaction.
596 | Green Chem., 2012, 14, 2595–2599
2
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Fig. 6 Mechanism of the conjugate addition reaction by indirect electrolysis.
Table 1 Yields of coupling products 6–8
Entry
X
Z
Coupling products
Isolated yield (%)
1
2
3
4
I
Br
N
OTs
COCH
3
75
72
72
68
Fig. 8 Creation of carbon–carbon bonds from activated glycerol 1,2-
carbonate using PC as a solvent.
3
5
6
7
8
I
Br
N
OTs
CO
2
Bu
73
70
67
68
Table 2 Yields of coupling products 6–8 with PC
3
Entry
X
Z
Coupling products
Isolated yield (%)
9
1
I
Br
N
OTs
CN
70
66
64
66
0
1
2
3
4
I
Br
N
OTs
COCH
3
73
74
64
68
1
1
3
1
2
3
5
6
7
8
I
Br
N
OTs
CO
2
Bu
66
65
64
68
secondary product is always propylene carbonate (PC) with
about 10% yields. Moreover, the excess of olefins can be
recycled.
However, one of the main objectives of this work was to save
steps in the preparation of the activated product. We wished to
bypass the halogenation step and consequently save time, energy
and solvents. We realized the same coupling reactions in the
optimized reaction conditions with tosylated glycerol 1,2-carbon-
ate (Fig. 5).
3
9
10
I
Br
N
3
OTs
CN
60
60
55
63
1
1
1
2
Another important point of our work consists of replacing
Similar results were obtained; we observed and isolated
compounds 6–8 with yields of ca. 70% (Table 1). These results
are particularly interesting and unprecedented to this day
because the same reaction realized with the tosylated octanol and
the electrodeficient olefins has never led to the conjugate
addition product unlike iodooctane which gave 88% of yield
DMF by a more environment-friendly solvent. So, we chose pro-
pylene carbonate (PC), which is a derivative of glycerol 1,2-car-
bonate, as a green solvent, we realized the same reactions in this
solvent using the optimized reaction conditions (Fig. 8). Coup-
ling products 6–8 were observed and isolated. Table 2 shows the
obtained results.
Table 2 indicates that the PC led to good results. The coupling
products were obtained with similar yields. This solvent is a
good alternative to the use of DMF.
(Fig. 7).
3
. Conclusions
This research has shown that the activation of halogen or
pseudo-halide derivatives of glycerol 1,2-carbonate mediated by
Fig. 7 Reaction from tosylated octanol and iodooctane.
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nickel catalysis is effective and leads to the creation of new
carbon–carbon bonds with electron deficient olefins. One step
electrochemical procedures then remain of high interest. Indeed,
in organic synthesis, conjugate additions are often used. In the
chemical routes, the use of either organocuprate reagents, or
organometallic reagents in the presence of copper salt, are the
classical methods of regioselective 1,4-addition. These
procedures require, as the preliminary step, the preparation of
air- and/or moisture-sensitive organometallic reagents (such as
organomagnesium). Problems in functional compatibility are
encountered when the organometallic reagent is from a precursor
bearing sensitive functional groups such as a ketone. Thus, the
sacrificial anode-based electroreductive process is a very efficient
method which is compatible with the presence of functional
groups and more particularly carbonate function, for this one is
not modified during the reaction. Moreover, we have also shown
that the tosylated glycerol 1,2-carbonate gives good results and
the secondary product obtained through these coupling reactions
can be used as an environment-friendly solvent. The use of tosy-
lated glycerol 1,2-carbonate is very interesting because this com-
pound is easily obtained in one step. To our knowledge, this is
the first report of creation of carbon–carbon bonds on the gly-
cerol 1,2-carbonate and of the synthesis of these compounds.
These coupling reactions have also been tested on the other
by-products of glycerol, and more particularly on the solketal,
giving good preliminary results with ca. 40% yields for each of
maXis mass spectrometer by the “Fédération de Recherche”
ICOA/CBM (FR2708) platform.
3-O-Tosyl glycerol 1,2-carbonate 2 was prepared according to
ref. 24; NMR spectra are in agreement with literature data.
4
.2. Standard procedure for the synthesis of 3 and 4
A solution of 3-O-tosyl glycerol 1,2-carbonate 2 (0.272 g,
1
mmol) and tetra-n-butylammonium iodide or bromide (7
equiv.) in anhydrous acetone (5 mL) was heated under reflux for
3
3
h. The reaction was monitored by GC and stopped after the
-O-tosyl glycerol 1,2-carbonate was consumed. After cooling
and evaporating, the mixture was diluted with ethyl acetate and
water and the aqueous phase was extracted three times with ethyl
acetate. The organic phase was washed with water, brine and
dried over MgSO . After filtration and concentration of the solu-
4
tion in vacuo, the residue was purified by column chromato-
graphy on Sephadex LH-20 eluting with n-heptane–CH Cl –
2
2
MeOH (2 : 1 : 1) then CH Cl –MeOH (1 : 1) and finally 100%
2
2
MeOH leading to compounds 3 or 4 with 90% yield.
15,17
4.2.1. 4-(Iodomethyl)-1,3-dioxolan-2-one.
Compound 3
was isolated by n-heptane–CH Cl –MeOH (2 : 1 : 1) in 90%
2
2
yield as a white solid. NMR, MS and IR spectra are in agreement
with literature data.
4
.2.2. 4-(Bromomethyl)-1,3-dioxolan-2-one. Compound
4
the conjugate addition products (X = I, Br, N , OTs and Z =
3
was isolated by n-heptane–CH Cl –MeOH (2 : 1 : 1) in 90%
2
2
COCH , CO Bu, CN). We can thus confirm that the coupling
3
2
1
yield as a yellow oil. H NMR (400 MHz, CDCl ) δ 4.96 (m,
3
reaction by electrochemical methods is compatible with the pres-
ence of functional groups. However, this reaction ought to be
optimized.
Preliminary tests using the diethylcarbonate, solketal and gly-
cerol 1,2-carbonate as environment-friendly solvents have led to
encouraging results. These conjugate addition reactions will be
optimized and tested in the other green solvents and realized on
other by-products of glycerol.
1
H, H-3), 4.59 (t, 1H, J = 8.8 Hz, H-2a), 4.34 (dd, 1H, J = 6.2
13
Hz, H-2b), 3.58 (m, 2H, BrCH2). C NMR (100 MHz, CDCl3)
δ 154.27 (CO), 74.10 (C-3), 68.24 (C-2), 31.57 (CH Br). IR
2
1
776 (CO).
17,25
4.3. Synthesis of 4-(azidomethyl)-1,3-dioxolan-2-one 5
To a solution of tosylated glycerol 1,2-carbonate 2 (0.5 g,
1
.836 mmol) in 4 mL of anhydrous DMF, 2 equiv. of NaN was
3
4
. Experimental
added and the reaction mixture was heated for 18 h at 70 °C.
After cooling and evaporating, the mixture was washed with
pentane and diluted with dichloromethane and water. The
aqueous phase was extracted three times with dichloromethane
and the organic phase was washed with water, brine and dried
4
.1. General
All chemicals were purchased from Aldrich, TCI or Acros
Organics. Solvents were commercially available and used as
received without any further purification. Reactions were moni-
tored by TLC analysis on precoated silica gel plates (Kieselgel
over MgSO . After filtration and concentration of the solution
4
in vacuo, compound 2 was isolated in 89% yield as a colorless
oil. NMR spectra are in agreement with literature data.
6
0F254, E. Merck); spots were visualized with UV light and
charring after a vanillin solution spray.
The electrochemical reaction was followed by GC until com-
plete conversion of the substrate.
4
.4. Standard procedure for the synthesis of compounds 6–8
Column chromatography was performed on alumina (neutral,
Merck) using mixtures of n-heptane and ethyl acetate or deacti-
vated silica gel Si 60 (43–60 mm; Merck) using mixtures of
CH Cl –MeOH or by size exclusion chromatography on Sepha-
Under Ar, in an undivided cell equipped with a nickel grid (area
30 cm ) as the cathode and an iron rod as the anode, tetrabutyl-
2
ammonium bromide (0.35 mmol) and tetrabutylammonium
iodide (0.21 mmol) were dissolved as supporting electrolytes in
a mixture of DMF (24 mL) (or environment-friendly solvent)
and pyridine (2.5 mL). A short electrolysis was conducted in the
presence of 1,2-dibromoethane (0.90 mmol) at constant current
density (0.2 A dm− ) and at r.t. within 15 min to generate a
small amount of iron ions. Then the current was turned off.
NiBr ·3H O (0.70 mmol, 153 mg), the activated olefin
2
2
dex LH-20 eluting with n-heptane–CH Cl –MeOH (2 : 1 : 1)
2
2
then CH Cl –MeOH (1 : 1) and finally 100% MeOH.
2
2
1
13
H NMR and C NMR spectra were recorded at 400 MHz
2
and 100 MHz (Bruker). Chemical shifts are given in ppm
downfield from internal standard TMSCl (δ = 0 ppm). High-
resolution mass spectra (HRMS) were performed on a Bruker
2
2
2598 | Green Chem., 2012, 14, 2595–2599
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(
18.9 mmol) and the activated glycerol 1,2-carbonate (7 mmol)
The electrodeficient olefin used for the synthesis of 8 was ACN.
The compound 8 was purified on an alumina column eluted with
n-heptane–ethyl acetate mixtures of increasing polarity and
were added. The mixture was then heated at 76 °C. The electro-
synthesis was run at constant current density (0.2 A dm− ). The
reaction was monitored by GC and stopped after the activated
glycerol 1,2-carbonate was consumed. After concentration of the
solution in vacuo, the crude product was thus subjected to
column chromatography to give the purified compounds 6–8.
2
1
obtained as a yellow oil with 30% ethyl acetate. H NMR
(400 MHz, CDCl ) δ 4.74 (m, 1H, H-3), 4.58 (t, 1H, J = 8.3 Hz,
3
H-2a), 4.10 (dd, 1H, J = 8.3, 7.2 Hz, H-2b), 2.45 (m, 2H, H-6),
13
1.91 (m, 4H, H-4 and H-5). C NMR (100 MHz, CDCl ) δ
3
1
(
54.60 (CO-1), 118.09 (CN), 76.00 (C-3), 69.23 (C-2), 32.98
C-4), 21.18 (C-5), 17.05 (C-6). ESI-HRMS calcd for
C H O NNa: 178.1421. Found: 178.0475, IR 2210 (CN), 1776
4
.4.1. Synthesis of compound 6.
7
9 3
(CO).
Acknowledgements
The electrodeficient olefin used for the synthesis of 6 was MVK.
The compound 6 was purified by column chromatography on
Sephadex LH-20 eluting with n-heptane–CH Cl –MeOH
We are grateful to the “Fédération de Recherche” ICOA/CBM
(FR2708) platform for spectral data measurement and to Dr
I. Lachaise for her help.
2
2
(
2 : 1 : 1) and CH Cl –MeOH (1 : 1) or by deactivated silica gel
2 2
Si 60 using mixtures of CH Cl –MeOH. The compound was
2
2
obtained as a yellow oil on sephadex with n-heptane–CH Cl –
2
2
MeOH (2 : 1 : 1) and CH Cl –MeOH (1 : 1) or by deactivated
2
2
Notes and references
1
silica gel Si 60 with 30% MeOH. H NMR (400 MHz, CDCl )
3
1
2
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δ 4.69 (m, 1H, H-3), 4.54 (t, 1H, J = 8.2 Hz, H-2a), 4.09 (dd,
1
H, J = 8.4, 7.2 Hz, H-2b), 2.54 (t, 2H, J = 5.3 Hz, H-6), 2.16
1
3
(s, 3H, H-8), 1.75 (m, 4H, H-4 and H-5). C NMR (100 MHz,
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3
3
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8
12
4
4 R. De Sousa, C. Thurier, C. Len, Y. Pouilloux, J. Barrault and F. Jérôme,
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4
.4.2. Synthesis of compound 7.
6
7
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2
1
1
The electrodeficient olefin used for the synthesis of 7 was ABu.
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1
1
5
CH Cl –MeOH (2 : 1 : 1) and CH Cl –MeOH (1 : 1). H NMR
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2
2
2
1
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4
400 MHz, CDCl ) δ 4.96 (m, 1H, H-3), 4.59 (m, 1H, H-2a),
.41 (m, 1H, H-2b), 3.75 (t, 2H, J = 7.6 Hz, H-9), 2.31 (m, 2H,
3
1
H-6), 1.58 (m, 6H, H-4, H-5 and H-10), 1.36 (m, 2H, H-11),
0
1
1
3
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3
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11 18 5
2
53.2482. Found: 253.1030, IR 1778 (CO).
.4.3. Synthesis of compound 8.
1
1
2
2
2
2
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This journal is © The Royal Society of Chemistry 2012
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