Carbohydrate Research 350 (2012) 6–13
Contents lists available at SciVerse ScienceDirect
Carbohydrate Research
journal homepage: www.elsevier.com/locate/carres
Modifications in the nitric acid oxidation of D-glucose
Tyler N. Smith a, Kirk Hash a, Cara-Lee Davey b, Heidi Mills b, Holly Williams a, Donald E. Kiely a,⇑
a
b
Shafizadeh Rocky Mountain Center for Wood and Carbohydrate Chemistry, The University of Montana, Missoula, MT 59812, USA
Chemistry Department, University of Waikato, Private Box 3105, Hamilton, New Zealand
a r t i c l e
i n f o
Article history:
Received 8 November 2011
Received in revised form 22 December 2011
Accepted 23 December 2011
Available online 4 January 2012
Keywords:
D-Glucaric acid
Nitric acid oxidation
Diffusion dialysis
Nanofiltration
Ion chromatography
Monopotassium D-glucarate
a b s t r a c t
The nitric acid oxidation of D-glucose was reinvestigated in an effort to better understand and improve
the oxidation and subsequent work up steps. The oxidation was carried out using a computer controlled
reactor employing a closed reaction flask under an atmosphere of oxygen which allowed for a catalytic
oxidation process with oxygen as the terminal oxidant. Removal of nitric acid from product included
the use of both diffusion dialysis and nanofiltration methodologies. Product analysis protocols were
developed using ion chromatography.
Ó 2012 Elsevier Ltd. All rights reserved.
1. Introduction
Despite its commercial potential, large scale production of
acid by nitric acid oxidation of D-glucose has been hindered, primarily due to competing side reactions which result in
low conversion to D-glucaric acid (<50% yield) and the rapid and
highly exothermic character of the oxidation. Alternative oxidization methods to 2 have been reported that include catalytic oxidation with oxygen using a platinum catalyst,15 and chlorine and
bromine based oxidations employing TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl)16–18 as a catalyst. The metal catalyzed reaction
shows slightly improved yields of D-glucaric acid (54% yield), while
the TEMPO-based oxidations report higher glucaric acid conversion
(70–90% yield) but require relatively expensive oxidizing agents.
Biochemical production of D-glucaric acid has also been demonstrated using a process that first converts myo-inositol to D-glucuronic acid followed by an enzymatic or metal-catalyzed oxidation
to D-glucaric acid.19 A second reported biological synthetic route
to D-glucaric acid originates from D-glucose in recombinant Escherichia coli.20 Although D-glucaric acid is indicated as the target molecule in the described oxidations, it was conveniently isolated as
monopotassium D-glucarate (3) since crystalline D-glucaric acid
does not lend itself as readily to crystallization. However, an Xray crystal structure of D-glucaric acid was recently reported.21
D-glucaric
D-Glucaric acid (2) is a naturally occurring aldaric acid, typically
found in small amounts in a variety of fruits and vegetables.1,2 The
synthetic preparation of D-glucaric acid dates back to the 1888 report of Sohst and Tollens who carried out the nitric acid oxidation
of D-glucose (1) to D-glucaric acid (2), isolated as monopotassium
3
D-glucarate (3) (Scheme 1).
In the mid 20th century, nitric acid oxidation of D-glucose to
4,5
D-glucaric acid,
was carried out with reasonable success on a pilot plant scale,6 but never commercialized. Potential commercial
applications for D-glucaric acid include use as a metal sequestering
agent,7,8 retarding agent for metallic mordants in the dyeing of textiles,5 and corrosion inhibitor for metals.9,10 A current commercial
use of a salt form of 2 is as a dietary supplement, claimed to help
maintain healthy cholesterol levels1 and prevent cancer.11,12 As a
dietary supplement, 2 functions as a precursor to the b-glucurondidase inhibitor, D-glucaro-1,4-lactone. In addition to these end uses,
D-glucaric acid is the starting material for the synthesis of other
chemicals, particularly as a diacid monomer used to make a number of polyhydroxypolyamides.13 The commercial potential of Dglucaric acid was recently underscored in a report from the Department of Energy which identified the molecule as one of the top 12
undeveloped building blocks that could be produced from
biomass.14
⇑ Corresponding author. Tel.: +1 406 549 6126.
E-mail addresses: [email protected], [email protected] (D.E. Kiely).
0008-6215/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
doi:10.1016/j.carres.2011.12.024
2. Results and discussion
Although modest yields (40–45%) of D-glucaric acid are realized
by nitric acid oxidation of D-glucose, the method remains attractive
for commercialization because of its relative simplicity with nitric
acid serving as both solvent and source of the oxidizing agent.22
7
T. N. Smith et al. / Carbohydrate Research 350 (2012) 6–13
OH
O
HO
HO
OH
OH
H
1
HNO3
O
OH OH
OH
HO
Organic Acid
+ Side
Products
O
KOH
OH OH
OK
HO
OH OH O
Acid Side
+ Organic
Product Salts
OH OH O
2
3
Scheme 1. Nitric acid oxidation of D-glucose to D-glucaric acid.
Because of the potential this oxidation offers, we were motivated
to reinvestigate it in order to generally learn more about oxidation
behavior, and specifically to determine and possibly control oxidation selectivity. To those ends, the oxidation was carried out under
computer control, the reaction being conducted under an atmosphere of oxygen in a closed reaction flask in order to effect a catalytic oxidation process using oxygen as the terminal oxidant. In
the oxidation workup, diffusion dialysis and nanofiltration methodologies for separation of nitric acid and nitrate, respectively,
were employed as alternatives to the removal of nitric acid from
a heated reaction mixture by evaporation at reduced pressure.
An HPLC method was employed that cleanly separated nitric acid
from organic acids in reaction mixtures but did not provide adequate separation of organic acid components. However, a satisfactory ion chromatographic protocol was then developed for the
analysis of both organic and inorganic components of oxidation
product mixtures.
2.1. Reactor setup
A Mettler Toledo LabMax reactor under computer control was
employed for all the oxidations described with the computer programed to control reactor temperature, stirring rate, reactor pressurization with oxygen, and addition of liquid solutions to the
reactor. Prior to each reaction, the jacketed reaction flask was
charged with nitric acid (68–70%), closed to the atmosphere, and
computer control initiated. The reaction flask was then set to a predetermined temperature and pressurized with oxygen. Programmatic addition of an aqueous solution of D-glucose, containing a
small amount of inorganic nitrite as a reaction initiator, was then
carried out over time, at designated reaction flask temperatures,
using an automated liquid reactant feed system. Nitric acid oxidations of sugars typically display an induction period where the
reaction mixture temperature is stable for a period of time, followed by a shorter period wherein the temperature of the reaction
mixture gradually rises, and then a very brief period in which the
temperature of the reaction mixture rises rapidly to almost boiling
accompanied by evolution of large amounts of gas, particularly visible brown nitrogen dioxide (NO2).
Given the potential danger associated with the exothermic
character of the oxidation, particularly on a large commercial scale,
a critical goal of this study was to establish thermal control of the
oxidation. The use of a computer-controlled reactor allowed for
managed addition of oxidizable substrate (D-glucose) to nitric acid
over time, which was very important in the control of reaction
temperature. An oxygen atmosphere was maintained in the reaction flask in order to oxidize colorless nitric oxide (NO) to nitrogen
dioxide, which over time is converted into nitric acid.23 Oxygen has
been used as a cooling gas in similar oxidations, but not in a closed
reactor for the oxidation of nitric oxide.24 A number of oxidation
protocols were designed and the two described here employed different reaction times, reaction temperatures, and D-glucose to nitric acid molar ratios. An important objective of the project was
to establish general computer-controlled reactor oxidations protocols that could provide a platform for eventual oxidation
optimization.
In the above process, oxygen becomes the terminal oxidant,
ultimately fostering regeneration of spent nitric acid and lowering
the amount required. In effect nitric acid is the catalyst in this process and oxygen the consumable oxidizing agent. In typical oxidations a 4:1 molar ratio of nitric acid to D-glucose was employed, the
D-glucose added as a 62.5% aqueous solution, an initial dose of glucose solution was generally followed by a waiting period without
glucose addition and then the remaining and larger amount of glucose added. The temperature range for oxidation was 25–40 °C,
and the reaction flask maintained at set pressures between 0.25
and 0.5 atm (3.7–7.3 psig). Overall, the oxidation was successfully
carried out with much more control and at lower temperatures
then previously reported but without greater selectivity. D-Glucaric
acid is the dominant product, the major co-products being the
monocarboxylic acids D-gluconic acid and 5-ketogluconic acid,
and the dicarboxylic acids, tartaric acid, tartronic acid, and oxalic
acid, the later three arising from oxidative carbon–carbon bond
cleavage.
A number of oxidations were carried out in order to gain an
understanding of how altered reaction conditions changed the outcome of the oxidation. It was quickly realized that a variety of reaction conditions gave acceptable results and that at a production
level, the choice of conditions would depend on the scale at which
the oxidation was applied. Furthermore, very reproducible experimental results were realized from the oxidations carried out under
the computer control conditions employed. Given the reaction control that is possible for this oxidation, a choice of reaction conditions is available depending upon the need.
2.2. Comments on the oxidation mechanistic pathway
A recent report describing the reaction kinetics of nitric acid
oxidative decarboxylation of 3,4-methylenedioxymandelic acid
proposes a mechanistic pathway25 that generally fits our experimental observations. Oxidation at hydroxylated carbons occurs
via nitrite esters from nitrous acid initially generated from the
reaction of sodium nitrite and nitric acid. A nitrite ester then
breaks down to the corresponding carbonyl product (aldehyde, ketone, or lactone) and HNO, which then reacts with nitric acid to
generate more nitrous acid and NO. A separate kinetic study concerned with the nitric acid oxidation of benzyl alcohol26 also concluded that nitrous acid was the active oxidizing agent and showed
that the concentration of nitrous acid increases steadily, which
could account for the oxidation rate increase and exothermic character of the D-glucose oxidations. Our experience with nitric acid
oxidations of D-glucose and other simple sugars indicates to us that
the mechanistic pathways associated with these oxidations parallel those described as above,25,26 but as yet are not thoroughly
understood.
2.3. Oxidation product chromatographic analysis
2.3.1. HPLC
GC/MS can be used as a routine analytical method to identify
organic components of nitric acid oxidations as their O-TMS derivatives. However, it was imperative to employ a convenient chro-
8
T. N. Smith et al. / Carbohydrate Research 350 (2012) 6–13
matographic method that could be directly used for both organic
products and inorganic nitrate and did not require derivatization
steps. Our initial effort was to develop an HPLC method for the
analysis of carbohydrate acids similar to one previously described
by Blake et al.27 Our method employed two Aminex HPX-87 cation
exchange resins connected in series, the first held at 35 °C and the
second at 85 °C, a refractive index detector, and 0.005 M sulfuric
acid as eluent.28 Typical product mixtures from nitric acid oxidation of D-glucose include D-glucaric acid (the dominant product),
plus varying amounts of D-gluconic acid, tartaric acids, 5-keto-Dgluconic acid, tartronic acid, D-glucose, oxalic acid, and nitric acid.
Nitric acid and oxalic acid showed baseline separation at 14.0 and
15.4 min, respectively, but the peaks from the carbohydrate components, 18.32–21.0 min were broad, overlapping, and showed
no baseline separation. It was determined that the weakly acidic
eluent-catalyzed lactone formation of the six carbon acids, resulting in multiple components and multiple peaks for a single species.
The lack of good separation of organic products rendered the method unsatisfactory for complete reaction mixture analysis but was
suitable for screening the nitric acid content of oxidation mixtures.
2.3.2. Ion chromatography
An ion chromatography (IC) method for the analysis of these
oxidation mixtures and related samples from the work-up and
purification processes was then established.29 The method employed a Dionex ICS2000 IC system equipped with an AS11-HC column and a suppressed conductivity detector. IC proved to be a
useful, versatile and straightforward method for routine analysis
of the oxidation mixtures. The detected ions included the anionic
salt forms of D-glucaric, D-gluconic, 2- and 5-keto-D-gluconic, glycolic, oxalic, tartaric, tartronic, and nitric acid. Separation of the
respective components was significantly improved over that observed with the HPLC method, and was characterized by narrow
component peaks with baseline separation. At this time, a standard
protocol for quantifying the individual components is still being
developed.
IC chromatograms from a typical oxidation prior to removal of
nitric acid, and after evaporation of the bulk of nitric acid at reduced pressure are shown in Figures 1 and 2, respectively. The
chromatogram in Figure 2 shows a significant decrease in the
amount of nitric acid present relative to the organic acid amounts
and illustrates that the relative amounts of organic acids has changed due to continued oxidation during the nitric acid evaporation
step with less D-gluconic acid and more D-glucaric acid in the
mixture.
2.4. Nitric acid removal
2.4.1. Nanofiltration
A standard method for the removal of nitric acid from an oxidation mixture is by evaporation, with heat, at reduced pressure, a
method that is relatively harsh and is accompanied by further,
but less controlled oxidation. Procedures have been reported to
limit the amount of nitric acid that have to be evaporated from carbohydrate oxidations and include adding 2-propanol prior to evaporation to consume some of the nitric acid,30 or removing a portion
of the nitric acid from the reaction mixture by ether extraction.31
As seen by a comparison of Figures 1 and 2, nitric acid evaporation
proceeds with additional oxidation. The extent of oxidation at the
evaporation step is dependent on the temperature of the reaction
mixture and the time required to complete the evaporation.
Clearly, controlled oxidation in the reactor is favored over less controlled oxidation in an evaporator. More complete oxidation in the
reactor can limit the extent of oxidation in the evaporator, maximize glucaric acid formation and limit co-products formation, particularly oxalic acid.
As an alternative method to evaporation for the removal of nitric acid, size selective membrane filtration was tested as a way
to separate inorganic nitrate salts from the organic co-product salts
while preventing additional oxidation. A feedstock solution for
nanofiltration (NF) was produced from oxidation reaction mixtures
from which limited amounts of nitric acid had been removed by
evaporation followed by dilution with water and basification with
hydroxide. Basification of the reaction solution was also necessary
to prevent corrosion of the filtration system with nitric acid. A
solution was fed into the nanofiltration system under applied pressure and two output streams generated, one containing components that passed through the filter (permeate) and one
Figure 1. IC chromatogram of a typical reaction mixture from the nitric acid oxidation of D-glucose.
T. N. Smith et al. / Carbohydrate Research 350 (2012) 6–13
9
Figure 2. IC chromatogram of a concentrated reaction mixture from the nitric acid oxidation of D-glucose.
Figure 3. HPLC chromatogram of the nanofiltration feedstock from nitric acid oxidation of D-glucose.
containing components unable to pass through the filter (retentate). Degree of separation of inorganic nitrate from organic products was determined using the HPLC method described. The HPLC
chromatograms of a typical oxidation feedstock, the retentate and
the permeate are shown in Figures 3–5, respectively.
As a separation process, nanofiltration worked well for this
application, showed high selectivity for nitrate removal, with relatively small amounts of oxalate and monovalent D-gluconate passing through the filter. However, a drawback of the nanofiltration
was that it required a dilute feedstock solution to avoid high
back-pressure in the system. Additional water was also required
during the filtration process to avoid low flow rates. Consequently,
a very dilute product stream was produced which required considerable evaporation of water at reduced pressure prior to the isolation of D-glucaric acid as its monopotassium salt. On a commercial
scale, distillation of large volumes of water is energy intensive and
ultimately could render the nanofiltration method impractical.
2.4.2. Diffusion dialysis
A second nitric acid separation method evaluated was diffusion
dialysis (DD). Diffusion dialysis is a technique used to recover strong
acids from aqueous mixtures containing multivalent metal ions and
is commonly used in metal processing applications such as anodizing and pickling.32,33 The DD system relies upon a cationic membrane stack which partitions the solution to be separated from a
counter flow of pure water. The strong acid dissociates in solution
to form an anion/hydronium ion pair. The anion passes through
the positively charged membrane into the counter flowing water
along with hydronium ion while the larger metal cations are retained. As far as we are aware DD had not previously been applied
10
T. N. Smith et al. / Carbohydrate Research 350 (2012) 6–13
Figure 4. HPLC chromatogram of the nanofiltration retentate from nitric acid oxidation of D-glucose.
Figure 5. HPLC chromatogram of the nanofiltration permeate from nitric acid oxidation of D-glucose.
to the separation of strong inorganic acids from organic acids such as
those generated in the nitric acid oxidation of D-glucose. However, it
proved to be an effective separation method when applied to nitric
acid/organic acid product mixtures, as will be described. Currently
there is no clear mechanism as to how the product acids are separated from the inorganic acids using this process, since the former
bear little structural resemblance to multivalent metal ions. Like
nanofiltration, DD produces two streams, one rich in nitric acid
and one rich in organic acids. In contrast to nanofiltration, the DD
system can utilize a feedstock solution with high concentration
and low pH and does not require removal of large amounts of water,
thus facilitating recycling of the reclaimed nitric acid stream for use
in subsequent oxidation reactions. In addition, the DD system operates near atmospheric pressure and requires relatively little energy
input. IC was used to evaluate the separation efficiency of DD in nitric acid removal from the oxidation reaction mixture. The reaction
mixture (Fig. 1) was concentrated to remove the dissolved gases, diluted with an amount of water equal to distillate removed and then
used as the DD feedstock. An IC chromatogram for the organic product stream (Fig. 6) shows efficient removal of nitric acid from the
reaction mixture. The reclaimed nitric acid stream chromatogram
(Figure 7) does contain significant bleed through of the organic acids
(ca. 15–20%), primarily D-glucaric acid, but if required, could be subjected to partial evaporation and a second DD treatment to recover
more product. The clear take home lesson from the use of DD in this
application is that it offers an additional effective opportunity for the
separation of strong acid from carbohydrate materials under very
mild conditions.
T. N. Smith et al. / Carbohydrate Research 350 (2012) 6–13
11
Figure 6. IC chromatogram of the diffusion dialysis organic product stream from the nitric acid oxidation of D-glucose.
Figure 7. IC chromatogram of the diffusion dialysis reclaimed nitric acid stream from the nitric acid oxidation of D-glucose.
2.5. Isolation of monopotassium D-glucarate (3)
For purposes of this study a standard procedure for isolating
mono-potassium D-glucarate (3) from different oxidation and work
up schemes was employed.5 The method involved basification of an
oxidation reaction mixture with potassium hydroxide followed by
acidification to a pH 3–4 wherein 3 precipitates. For example, after
the oxidation was carried out using 4 equiv of nitric acid, followed by
concentration of the reaction mixture to remove some residual nitric
acid, 3 was isolated in a yield of 45% of theoretical, comparable to
that previously reported (41%).5 Repeating the oxidation followed
by passing the potassium hydroxide neutralized oxidation mixture
through the nanofiltration unit, and acidifying the retentate to pH
3–4 gave 3 in a 43% isolated yield, slightly lower and probably due
to bleed through of D-glucarate into the nitrate permeate stream.
Monopotassium D-glucarate (3) isolated in this study was characterized by 1H NMR and ion chromatographic comparison of the isolated
product with that of authentic 3.5
3. Summary
A computer controlled reactor was successfully employed to demonstrate controlled nitric acid oxidation of D-glucose (1), in a closed
reactor under a positive pressure of oxygen, to D-glucaric acid (2), iso-
12
T. N. Smith et al. / Carbohydrate Research 350 (2012) 6–13
lated as monopotassium D-glucarate (3). The use of the computer controlled reactor provided necessary control of the highly exothermic
reaction, and allowed for oxidation at relatively low temperatures of
25–30 °C and catalytic oxidation with oxygen as the terminal oxidant.
Two methods of nitric acid removal, novel to this oxidation, were employed; a nanofiltration method that separated inorganic nitrate from
salts of the organic oxidation product, and diffusion dialysis that separated nitric acid directly from the organic oxidation products. An efficient ion chromatographic separation was developed for the analysis
of both organic and inorganic components of reaction mixtures. The
demonstrated improved control of nitric acid oxidation of D-glucose
coupled with convenient reaction mixture analysis by IC offers methodology that should prove beneficial to oxidation of other readily available carbohydrates.
4. Experimental
4.1. General methods
Solutions were concentrated in vacuo (15–20 mbar) using a rotary evaporator and water bath at 45 °C. Drying of samples was carried out at room temperature (unless otherwise noted) using a
mechanical pump. pH measurements were made with a Thermo Orion 310 pH meter (Thermo Fisher Scientific, Inc., Waltham, MA, USA)
which was calibrated using standard buffer solutions prior to use.
4.2. Analytical methods
A high performance liquid chromatography (HPLC) system was
employed28 with two Aminex HPX-87 cation exchange resins connected in series, the first held at 35 °C and the second at 85 °C. Sulfuric acid (0.005 M) served as the eluent and components were
detected using a refractive index detector. Ion chromatography
(IC) was performed using a method previously described.29 The IC
system consisted of a Dionex ICS2000 (Dionex Corporation, Sunnyvale, CA, USA) equipped with a 25 lL sampling loop, an AS11-HC
4 mm anion separation column fitted with an AG11-HC 4 mm guard
column, and a Dionex autosampler. The column was maintained at
38 °C. The suppressor was an ASRS ULTRA II auto-suppressor system.
The eluent was a water/NaOH mixture varying between 1 mM and
60 mM NaOH, created, and controlled with the use of an EG40 eluent
generator. The water component of the eluent was purified by a Millipore Simplicity 185 (Millipore Corporation, Billerica, MA, USA)
water purifier and was degassed with nitrogen prior to use. The columns were equilibrated with 1 mM NaOH for 4 min, and upon injection, the eluent concentration was ramped to 30 mM over 25 min
followed by a ramp to 50 mM over 2 min. The eluent concentration
was then held constant for 10 min before returning to 30 mM over
2 min.
4.3. Nitric acid oxidation reactor setup
All oxidation reactions were carried out using a LabMax automatic
lab reactor (Mettler Toledo, Columbus, OH, USA). The Labmax was designed to operate as a computer controlled closed-system reactor and
was fitted with a top-loading balance, a liquid feed pump, an oxygen
Sierra flow valve, a mechanically driven stirring rod, a thermometer,
a 2 L thermal jacketed flask, an FTS recirculating chiller, a pressure
manifold fitted with pressure relief valves and pressure gauge, and a
personal computer with CamileTG v1.2 software.
4.4. D-Glucose solutions
D-Glucose was used in the oxidations as a 62.3% solution. The
solution was prepared by dissolving anhydrous D-glucose (270.2 g,
1.50 mol) and dry sodium nitrite (1.20 g) in deionized water
(162.3 g) at 60 °C with stirring and allowing the solution (433.7 g)
to cool to room temperature prior to addition into the reactor.
4.5. Oxidation of D-glucose, 4:1 molar ratio of nitric acid to Dglucose
The procedure for the oxidation reaction was divided into nine
separate stages in the Recipe Menu of the Labmax Camille software. Stage 1: the temperature of the reactor jacket was set at
25 °C, the stirring rod speed set at 200 rpm (and held constant
throughout the remaining stages), and time set for 1 min. Stage
2: the reactor jacket temperature was set at 25 °C, the pressure
was set at 0.25 bar above atmospheric, and the time set for
3 min. Stage 3: the temperature and pressure were held constant,
and 43.3 g of 62.3% (w/w) D-glucose solution described above
was set to be added over 30 min. Stage 4: the temperature and
pressure were held constant, and the time set for 10 min. Stage
5: the temperature and pressure were held constant, and 172.9 g
of D-glucose solution was set to be added over 90 min. Stage 6:
the temperature and pressure were held constant for 5 min. Stage
7: the temperature was increased to 30 °C, the pressure was increased to 0.50 bar above atmospheric over 60 min. Stage 8: the
temperature and pressure were held constant, and time was set
for 90 min. Stage 9: the reactor temperature was set to cool to
25 °C over 10 min. Once the software was programed, aqueous nitric acid (187 mL, 3 mol) was added to the reactor, the reactor was
closed to the atmosphere, and the reaction recipe was initiated.
Upon completion of the oxidation process the reaction mixture
was further treated as described in the nanofiltration, diffusion
dialysis or monopotassium D-glucarate isolation procedures that
follow.
4.6. Oxidation of D-glucose, 3:1 molar ratio of nitric acid to Dglucose
The oxidation process was patterned after the 4:1 molar ratio of
nitric acid to D-glucose oxidation process but doubled the ingredient amounts and employed fewer stages. The oxidation procedure
was divided into six separate stages in the Recipe Menu of the Labmax Camille software. Stage 1: the temperature was set for 25 °C
(and held constant throughout all remaining stages) and the stirring rod speed set at 200 rpm (and held constant throughout all
remaining stages), time was set for 1 min. Stage 2: the pressure
was set at 0.25 bar above atmospheric (and held constant throughout all remaining stages), and the time was set for 3 min. Stage 3:
86.6 g of 62.3% D-glucose solution was set to be added over 30 min.
Stage 4: 10 min hold. Stage 5: 345.8 g of D-glucose solution was set
to be added over 90 min. Stage 6: 20 min hold. Once the software
was programed, aqueous nitric acid (282 mL, 4.5 mol) was added
to the reactor, the reaction recipe was initiated, and the reactor
was closed to the atmosphere.
4.7. Nitrate removal by nanofiltration
The nanofiltration unit was built in-house and comprised of
valves, pump, lines, a pressure gauge, and a GE DL2540F membrane. A typical D-glucose oxidation reaction mixture (4:1 molar
ratio of nitric acid to D-glucose) was concentrated, diluted with
water (370 mL), then made basic with aqueous solutions of either
sodium or potassium hydroxide. The basic solution was diluted to
give a volume of 4 L and used as a feedstock solution for the nanofiltration unit. The nanofiltration system produced two streams:
one passing through the filter (permeate) and one which does
not (retentate). The permeate was collected while the retentate
was fed back into the feedstock. When the permeate volume
T. N. Smith et al. / Carbohydrate Research 350 (2012) 6–13
reached 1 L, reverse osmosis (RO) purified water (1 L) was added to
the feedstock. The typical rate of the permeate flow when reducing
the volume by 1 L was 48 mL/min. When 2 L of permeate was removed, more RO water (1 L) was added to the feedstock. The typical rate of permeate flow when removing the second L was 45 mL/
min. This procedure was repeated until a total of 4 L of permeate
was collected and 4 L of RO water had been added to the feedstock.
The typical permeate flow rate when removing the last 1 L was
43 mL/min. The filtration process was continued after the last L
of RO water was added to the feedstock until the permeate flow
slowed to a trickle at which time the filtration was stopped. The final volumes of the retentate and permeate were 2.8 L and 5.2 L,
respectively.
4.8. Nitric acid removal by diffusion dialysis
The diffusion dialysis system was a Mech-Chem laboratory
scale acid purification unit (Model AP-L05, Mech-Chem Associates, Inc., Norfolk, MA, USA). The Mech-Chem unit contains two
metering pumps, an acid reclaim pump, and an acid reject pump.
The acid reject pump was set at 30% (pump length) and 30%
(pump speed), and the acid reclaim pump was set at 40% (pump
length) and 40% (pump speed), giving a flow through rate of
120 mL/h for the acid reclaim and 112 mL/h for the acid reject.
The system was first primed with RO water according to a standard setup procedure and then the water was removed from
the acid tank in the unit. The concentrated reaction mixture from
the oxidation of D-glucose reconstituted with water was added to
the acid feedstock tank. The water tank was filled with RO water
and two output streams, an inorganic acid recovery stream (reclaimed acid stream) and a product recovery stream (product
stream), were collected.
4.9. Monopotassium D-glucarate isolation from an oxidation
where nitric acid was evaporatively removed at reduced
pressure with heat
The pH of the concentrated reaction mixture from the oxidation
of D-glucose (4:1 molar ratio of nitric acid to D-glucose) reconstituted with water (370 mL) was adjusted to a constant pH of 9.5
with 45% KOH. The solution was cooled in an ice bath and titrated
to pH 3.4 with concentrated hydrochloric acid. A precipitate was
formed when the solution pH dropped below 5. The mixture was
cooled and held at 5 °C for 4 h and the precipitate then isolated
by filtration. The resulting solid cake was washed with cold water
and dried at reduced pressure for 18 h to give solid monopotassium D-glucarate (3), 83.2 g (45% yield from 134.3 g of dextrose).
4.10. Monopotassium D-glucarate isolation after nitrate
removal by nanofiltration
The retentate stream from the nanofiltration system was concentrated to an approximate volume of 300 mL. The concentrated
13
solution was cooled in an ice bath and the pH adjusted to a constant 9.5 with 45% KOH, then titrated to pH 3.4 with concentrated
hydrochloric acid. The resulting solid monopotassium D-glucarate
(3, 79.6 g, 43% yield) was isolated as described above.
Acknowledgements
This work was funded by USDA Cooperative State Research,
Education and Extension Service award No. 2001-34463-10521
and an EPSCoR Lab Partnership Grant 2000–2003. Special thanks
to Dr. John Vercellotti of V-LABS, Inc. for guidance in developing
the nanofiltration protocol.
References
1. Walaszek, Z.; Szemraj, J.; Hanausek, M.; Adams, A. K.; Sherman, U. Nutr. Res.
1996, 16, 673–681.
2. Perez, J. L.; Jayaprakasha, G. K.; Yoo, K. S.; Patil, B. S. J. Chromatogr. A 2008, 1190,
394–397.
3. Sohst, O.; Tollens, B. Liebigs Ann. Chem. 1888, 245, 1–27.
4. Mehltretter, C. L. U.S. Patent 2,436,659, 1948.
5. Mehltretter, C. L.; Rist, C. E. J. Agric. Food Chem. 1953, 1, 779–783.
6. Mustakas, G. C.; Slotter, R. L.; Zipf, R. L. Ind. Eng. Chem. 1954, 46, 427–434.
7. Mehltretter, C. L.; Alexander, B. H.; Rist, C. E. Ind. Eng. Chem. 1953, 45, 2782–
2784.
8. Abbadi, A.; Gotlieb, K. F.; Meiberg, J. B. M.; Peters, J. A.; van Bekkum, H. Green
Chem. 1999, 1, 231–235.
9. Korzh, E. N.; Sukhotin, A. M. Zh. Prikl. Khim. 1981, 54, 2404–2407.
10. Sukhotin, A. M.; Borshchevskii, A. M.; Korzh, E. N.; Perel’shtein, I. I.; Aref’eva, L.
N.; Kuslyaikin, G. A.; Parushin, E. B. Zashchita Metallov 1982, 18, 268–270.
11. Walaszek, Z. Cancer Lett. 1990, 54, 1–8.
12. Lampe, J. W.; Li, S. S.; Potter, J. D.; King, I. B. J. Nutr. 2002, 132, 1341–1344.
13. Kiely, D. E.; Chen, L.; Lin, T.-H. J. Am. Chem. Soc. 1994, 116, 571–578.
14. Werpy, T.; Petersen, G. Top Value Added Chemicals from Biomass, Volume 1:
Results of Screening for Potential Candidates from Sugars and Synthesis Gas.
U.S. Department of Energy, August 2004, pp 36–38. <http://
www1.eere.energy.gov/biomass/pdfs/35523.pdf>.
15. Mehltretter, C. L.; Rist, C. E.; Alexander, B. H. U.S. Patent 2,472,168, 1949.
16. Thaburet, J.-F.; Merbouh, N.; Ibert, M.; Marsais, F.; Queguiner, G. Carbohydr. Res.
2001, 330, 21–29.
17. Merbouh, N.; Thaburet, J.-F.; Ibert, M.; Marsais, F.; Bobbitt, J. M. Carbohydr. Res.
2001, 336, 75–78.
18. Merbouh, N.; Bobbitt, J. M.; Brückner, C. J. Carbohydr. Chem. 2002, 21, 65–77.
19. Schroeder, W. A.; Hicks, P. M.; McFarlan, S. C.; Abraham, T. W. U.S. Patent
7,326,549 B2, 2008.
20. Moon, T. S.; Yoon, S.-H.; Lanza, A. M.; Roy-Mayhew, J. D.; Prather, K. L. Appl.
Environ. Microbiol. 2009, 75, 589–595.
21. Denton, T. T.; Hardcastle, K. I.; Dowd, M. K.; Kiely, D. E. Carbohydr. Res. 2011,
346, 2551–2557.
22. Kiely, D. E.; Hash, Sr. Kirk R. U.S. Patent 7,692,041 B2, 2010.
23. Cotton, F. A.; Wilkinson, G. W. Advanced Inorganic Chemistry, 2nd ed.;
Interscience: New York, 1966. pp 341–353.
24. Kiely, D. E.; Carter, A.; Shrout, D. P. U.S. Patent 5,599,977, 1997.
25. Xi, H.; Gao, Z.; Wang, J. Ind. Eng. Chem. Res. 2009, 48, 10425–10430.
26. Joshi, S. R.; Kataria, K. L.; Sawant, S. B.; Joshi, J. B. Ind. Eng. Chem. Res. 2005, 44,
325–333.
27. Blake, J. D.; Clarke, M. L.; Richards, G. N. J. Chromatogr. 1987, 398, 265–277.
28. Mills, H. C. M.; M. Sc. Thesis, The University of Waikato, 2007.
29. Davey, C.-L.; M. Sc. Thesis, The University of Waikato, 2008.
30. Cantrell, C. E.; Kiely, D. E.; Abruscato, G. J.; Riordan, J. M. J. Org. Chem. 1977, 42,
3562–3567.
31. Kiely, D. E.; Ponder, G. U.S. Patent 6,049,004, 2000.
32. Bailey, D. E. U.S. Patent 5,264,123, 1993.
33. Olsen, D. R. and Bailey, D. E. U.S. Patent, 5,562,828, 1996.