Allison Eckert
Undergraduate Researcher
Telephone: (618) 975-3099
Email: [email protected]
April 26, 2017
Dr. Rainer Glaser, Professor of Chemistry
Editor, Journal of Organic Chemistry
Department of Chemistry, University of Missouri-Columbia
Columbia, MO 65201
RE: REVISED
The Synthesis of Adipic Acid through CO2 Utilization to Produce Nylon 6-6
By: Allison Eckert, Chris Gusmano, and Dillon James
Dear Dr. Glaser:
Thank you for your communication on April 20th with the peer reviews of our
original manuscript. We were pleased to see their suggestions and have taken them all
into consideration during the revising of our manuscript. Based off the recommendations
given to us by our peer reviewers, we have changed our manuscript accordingly. The
changes are described as follows:
Major Revision
[M.1] Data from Figure 1 and Figure 2 were discussed more in the text. Bridges were
included in the text where the figures were referenced.
[M.2] Sources were added in the introduction section of the paper.
[M.3] The issue with the scheme numbers was fixed.
[M.4] Specific data from Table 1 was added and referenced in the text.
[M.5] Table 2 was moved to the supporting information section. The supporting
information was alluded to more often in the description of the synthesis.
[M.6] Scheme 2 was redone to include color and a better mechanism that explains the
generic Grignard reaction.
Department of Chemistry
University of Missouri-Columbia
105 Chemistry Building
601 S. College Avenue
Columbia, Mo 65211
USA
mailto:[email protected]
3
[M.7] Consistency with grammar and format was improved by editing the entirety of the
paper.
Response to Reviewer 1
[1.1] Wording of the manuscript was revised to sound more continuous. Abstract and
introduction sections were edited with more descriptions and explanations. Paper was
thoroughly edited to improve the presentation and crispness of the manuscript.
[1.2] Nylon 66 was changed to nylon 6-6 where applicable. Please refer to [M.7].
[1.3] Scheme 2 was revised to account for color and confusion with the second halide
shown in the original. Please refer to [M.6].
[1.4] Table 1 was cited throughout the text in both the Material and Methods section and
Results and Discussion section. Please refer to [M.4].
[1.5] Table 2 was moved to the supporting information section. It was kept in the paper
to verify the significance of the structure and properties of Adipic acid and why it is the
best substrate to create Nylon 6-6. Please refer to [M.5]
[1.6] The electricity increase using the Grignard method was quantified in the results
section.
[1.7] Font sizes were changed to be a consistent 12 point font. Please refer to [M.7].
[1.8] Discussion section was expanded to include more correlations and differences
between synthesis methods.
Response to Reviewer 2
[2.1] Scheme numbers were fixed to go in order. Please refer to [M.3].
[2.2] Grignard reaction scheme was made clearer. Please refer to [M.6].
[2.3] Table 2 was moved to the supporting information section. It was kept in the paper
to verify the significance of the structure and properties of Adipic acid and why it is the
best substrate to create Nylon 6-6. Please refer to [M.5]
[2.4] CO2 was changed to CO2 throughout the paper. Please refer to [M.7].
[2.5] Titles go below figures only. This is proper JOC formatting.
[2.6] Figure 1 remains unchanged, but there is now information providing the reader what
the translation would equate to in American dollars. Please refer to [M.1].
4
Response to Reviewer 3
[3.1] Figures 1 and 2 were discussed more thoroughly in the text. Table 1, however, is
briefly mentioned in the Materials and Methods section. The table is referred to most
often in the Results and Discussion section. Please refer to [M.1].
[3.2] Sources were added in the introduction section of the paper. Please refer to [M.2]
[3.3] CO2 was changed to CO2 throughout the paper. Please refer to [M.7].
[3.4] Nylon 66 was changed to nylon 6-6 where applicable. Please refer to [M.7].
[3.5] Format of Results and Discussion subheadings were changed from all capital letters
to an italicized format.
[3.6] Font sizes were changed to be a consistent 12 point font. Please refer to [M.7].
Sincerely,
Allison Eckert, Chris Gusmano, and Dillon James
1
The Synthesis of Adipic Acid through CO2 Utilization to Produce Nylon 6-6
Allison Eckert, Christopher Gusmano, and Dillon James
Department of Chemistry, University of Missouri-Columbia, Columbia, Missouri, 65201
Email: [email protected] ; [email protected] ;
mailto:[email protected]:[email protected]:[email protected]
2
Abstract
It has been shown that atmospheric CO2 can be utilized to make many common
appliances that not only can be easily commercialized but can also reduce CO2 from
carbon storage sites. In this study, the Grignard reagent Adipic acid is produced from
1,4-butanediol and captured CO2 which will be further synthesized into Nylon 6-6. The
procedure and data were recorded and compared to two other methods for the synthesis
of Adipic acid, oxidation of cyclohexanone and the carboxylation of butadiene. The
Grignard synthesis of Adipic acid resulted in similar purity compared to the other two
methods. The new method featuring the Grignard reagent had the highest percent yield
along with the shortest reaction time compared to its competitors. Along with the value
increase that this new method provides, the Grignard synthesis of Adipic acid to form
Nylon 6-6 has shown potential results to make the current methods of Nylon 6-6
production inefficient.
3
Introduction
With drastic environmental impacts occurring, carbon capture methods and
technologies have become appealing and necessary processes to reduce CO2
concentrations in the atmosphere. Methods to avoid emissions include the production of
low carbon, carbon neutral, and carbon negative alternatives to common and bulk
chemicals.1 This can be accomplished through incorporating carbon dioxide into a desired
product. In this way, when the product is consumed or degraded, there is a reduced
change in atmospheric carbon dioxide levels associated with that product. Alkaline earth
metal compounds – such as Grignard reagents – have the ability to capture and activate
CO2 directly from the capturing process at room temperature and ambient pressures with
high yield and selectivity.
One major product synthesized from Grignard reactions is the carboxylic acid
derivative, Adipic acid (Scheme 1). The acid can be extracted from the magnesium nylon
salt formed during the preparation of the substrate through extraction, esterification,
and/or distillation.3
Scheme 1: Structure of Adipic Acid
Adipic acid is an important industrial dicarboxylic acid that is mainly used to
produce nylon 6-6 (Scheme 2). Nylon 6-6 is created by a step growth polymerization
4
reaction and a condensation polymerization from diacids and diamines.2 Nylon 6-6 has a
variety of uses such as textiles and 3D structural objects including ball bearing cages, air
intake manifolds, pipes, and various machine parts. Due to the diversity of uses of Nylon
6-6, there is a continually increasing economic market.
Scheme 2: Structure of Nylon 6-6
Here we report the results of a study conducted using various Grignard reagents
with CO2 in order to create Adipic acid versus other methods. The three different
methods of synthesis recognized include the substrates cyclohexanone, butadiene, and the
Grignard reagent reaction. It was hypothesized that the Grignard reagent synthesis could
potentially have the fastest and highest yielding reaction of adipic acid with relatively
low cost in comparison to other methods.
Materials and Methods
Preparation of Materials
Adipic acid is the primary component in the synthesis of nylon 6-6.1 Its synthesis
has been experimented with by trying various techniques. A new synthesis technique
regarding Grignard reagents and the capture of CO2 has been tested for economic use and
immediate employment. Adipic acid can be synthesized by using 1,4-butanediol and CO2
via a halogenation reaction.2 1,4-dichlorobutane is formed from the halogenation
5
reaction and used in the reaction to create nylon 6-6. Reaction of 1, 4-dichlorobutane with
sodium cyanide will alternatively produce hexylmethylenediamine (HMD), the other
main constituent of nylon synthesis. HMD and Adipic acid are combined in a 1:1 molar
ratio to form a magnesium nylon salt which can be further polymerized.3 The carboxylic
acid derivative – Adipic acid – is extracted from the magnesium salt by solvent
extraction, esterification, and/or distillation.4 From this method, a variety of substrates –
including Adipic acid – can be synthesized (Scheme 3).
Scheme 3.
6
Insertion of the carbon dioxide molecule between the carbon-magnesium bonds of
a halide is what characterizes this mechanism as a standard Grignard reaction (Scheme
4). This reaction is exothermic when carried out at 20 to 25°C and atmospheric pressure.2
High yields are obtained when these reaction conditions are observed and solvents with a
variety of side chains are utilized. Compared to the oxidation of cyclohexanone and
synthesis from butadiene, these temperatures and pressures account for a large value
increase (Table 1). Even though the purity remains approximately the same for all three
methods, the economic function for the Grignard reaction lies within short reaction time,
ambient temperatures and pressures, and middle-ground costs.
This method shows a dramatic increase in value for many of the substrates that
can possibly be synthesized. Substrates synthesized from Grignard reagents have the
potential for great commercial and environmental interest such as Adipic acid and nylon
6-6 synthesis. Adipic acid has approximately 657 Euros per ton value increase through
this method.2 A Euro is the equivalent to $1.09 United States’ dollars. The expected
value increase for our focused substrate (Adipic acid) equates to $716.13. Other
substrates such as acetic acid and acrylic acid show a substantial increase in value as well
(Figure 1). An increase in value of approximately $671.44 is expected for acetic acid
produced from the substrate methanol. About a $1,250 increase in value would be
observed from the synthesis of Acrylic acid from the reagent vinyl chloride. Over $1,500
from Terepthalic Acid of increased value could be seen as well.2 These four acids show
the economic reason behind the Grignard method.
7
Scheme 4.
Measuring Primary Function
Monomers for condensation polymerization contain types of functional groups.
Two functional groups are commonly seen with condensation polymerization unlike
addition polymerization mechanisms. For Adipic acid, we see two carboxylic acid
groups. Adipic acid’s carboxylic acid functional groups react with the amine (HMD) and
produce the corresponding amide linkage.5 This is the process of polymerization. Once
the amide linkage is formed, an amine group still remains on the outside of the molecule.5
This allows for the opportunity for another monomer of acid to react, creating an even
longer polyamide. The direct polymerization of 1,4-butanediol and CO2 show high
selectivity (Figure 2). A near 100% selectivity is important for the polymerization
process because slightly modifying the structure of any nylon will change its properties
dramatically.7 When synthesizing Nylon 6-6, high selectivity of the reagents is a
requirement.
Nylon 6-6 is named based on the number of carbon atoms from the diamine and
the dicarboxylic acid components – HMD and Adipic acid.3 Adipic acid is the most
crucial substrate for nylon 6-6 production because it is the best dicarboxylic acid for the
job. It has very low toxicity and no carcinogenic effects. It is not considered flammable
or explosive – the flash point is approximately 196°C and self-ignition temperature is
greater than 400°C (Table S2).6 The selectivity of Adipic acid is also optimal, which is
further explained in Figure 2.7 These characteristics make Adipic acid a proper monomer
8
for polymerization. More characteristic information is given in the supporting
information to express the significance of the properties of Adipic acid. A different
polymer would require a monomer that fits the desired structure.
Measuring the primary function of Adipic acid can be done with a variety of
different techniques. Any spectroscopy that shows the carboxylic acid of the substrate
and the amine that subsequently forms the polyamide shows the function. An FTIR
spectra of Nylon 6-6 shows the two main functional groups. When comparing the FTIR
spectra of the product to its components, the varying intensities of the wavenumbers
show the suitability of the polyamide formation. Analysis of the FTIR spectra of Adipic
acid is provided as Supporting Information.
9
Table 1: Comparison of Three Different Syntheses of Adipic Acid
Cyclohexanone Butadiene Grignard Reagent
Yield of Adipic Acid 87.1% 72% 95.2%
Time of Reaction 8 hours 10 hours 20 minutes
Cost of Reagent $890/ton $2000/ton $920/ton
Pressure 11.03 bar First Step: 600 bar
Second Step: 150 bar
1.00bar
U.S. Production 6 × 106 tons per year 1.21 × 105 tons/year 5.0 × 105 tons/year
Temperature 150-160°C Step 1: 130°C
Step 2: 170 ۤ °C
25.5-30.5°C
Purity of Adipic Acid >99% >99% >99%
10
Figure 1. Production of substrates from the different Grignard reagent reactions used to
produce them. Values of added value per raw material used are in Euros per ton.2 One
Euro is equal to $1.09 US dollars which means the four values above would go as
follows: $671.44 for Acetic Acid ( from Methanol), $716.13 Adipic Acid (from
Butanediol), $1255.68 Acrylic acid (from Vinyl Chloride), $1548.89 Terepthalic Acid
(from Benzene). Adipic acid synthesized from Butanediol is the main focus of this paper,
but it is shown that Grignard reagents and captured carbon have a broader impact than
only nylon 6-6 synthesis.
11
Figure 2. Time-course of direct polymerization of 1,4-butanediol and CO2.
• indicates the conversion of 1,4 butanediol to 1,4-dicholorbutane. ▵ indicates the
selectivity to 4-hydroxybutyl picolinate – an oligomer. This is significant because the
oligomer was not produced from the catalyst used in the direct polymerization reaction.
12
Results and Discussion
Results
This reaction was performed at atmospheric pressure and ambient temperatures.
High yields are obtained based on the dried components of reaction system and solvents,
with a wide range of possible R-groups. Apparatus and system of this reaction must be
dry because of violent reaction with water. The resulting carboxylic acid derivative from
the varying R-groups is isolated from the magnesium salt in the majority of cases by
solvent extraction or distillation. The rate of consumption of CO2 was measured based
on the pressure drop seen from sparging the 10 mL Grignard reagent (butane-1,4-
dimagnesium chloride) with CO2 intermittently. The data first appears to follow pseudo-
first order kinetics based on the constant CO2 concentrations. There was a change in rate
constant when the concentration of CO2 was changed due to the fact that the rate constant
is saturated at the maximum rate of CO2 consumption under the concentration
parameters. There is a strong dependence on both reagents. A decrease in the rate
constant is observed as the concentration of CO2 is lowered from 100%.
To measure the rate of the reaction, the CO2 consumption was measured by a
pressure transducer within the apparatus. The gas supply entered the round-bottom flask
from a sparging needle. Every minute, the flow of CO2 would be paused while the
readings were logged every 0.2 seconds from a pressure sensor following the condenser.
A pressure drop was observed due to the reaction with CO2. Constant values observed
were the gas bubbling periods. Once there was no pressure drop recorded during the
pause of CO2, the reaction was deemed complete. This took about 20 minutes for 100%
CO2 concentrations, which is remarkably fast in comparison to other methods of
synthesis. These measurements were used to calculate the reaction rates at different
13
concentrations of CO2. At 100% CO2, the pseudo rate constant was 5.49 x 10-3 s-1. At
50% CO2, the rate constant was lowered to 4.36 x 10-3 s-1.
Yields were decreased when the concentrations were lowered. When the
concentration of CO2 is lowered, the reaction time was then extended to complete the
reaction. This decrease in yields could be because of the sensitivity of Grignard chemistry
to the extended reaction time that corresponds with a decrease in concentration. An
extended reaction time increases the changes for contamination and moisture to appear in
the system. However, selectivity of the reagents were not affected from extended
reaction time. At normal conditions and 100% of CO2, yields of Adipic acid from this
reaction reached 95.2% due to the high selectivity of this reaction. Yields for the
supplemental Grignard reactions with the varying R-groups producing similar substrates
also give high yields.
Grignard reagents and captured carbon have a broader impact than only nylon 6-6
synthesis. Production of a wide range of substrates from the Grignard reagent reactions
shows production cost benefits and added values to these raw materials. It is estimated
that nearly 657 euros per ton of Adipic acid will be added to the current value.2
Electricity for the production of Adipic acid from the Grignard reagent method is higher
than industry values, which offsets the value increase of Adipic acid only slightly.
Electricity is increased by about 4.26 times per unit price of normal synthesis of Adipic
acid by oxidation of cyclohexanone. This increase brings electrical costs up
approximately 29.48 cents per kilowatt-hour.7
Reference Data
Adipic acid is most commonly synthesized by cyclohexane and butadiene. The
comparison data is listed out in Table 1. Cyclohexane and phenol form cyclohexanone.
14
This is then oxidized to form adipic acid and nitric acid. This method produces a higher
yield than butadiene at 87.1%. The total reaction takes approximately 8 hours at high
temperatures and pressures close to 11 bar. These requirements cause temperatures to
range from 150-160°C. This is the most commonly used industrial method to produce Adipic
acid.
Butadiene is a popular method, but used less because of lower yields and higher
production costs. 72% of Adipic acid is made from butadiene over 10 hours of synthesis.
This reaction requires extremely high pressures as well which contribute to the high
production costs. This first step must occur at 600 bar. Subsequently, the second step
occurs at 150 bar. Table 1 compares the reaction components and results between the use
of butadiene, cyclohexanone, and the Grignard reagent used to produce the data
explained in the results section.
Discussion
Adipic acid synthesis by Grignard chemistry is the quickest process with the
highest yields. Compared to cyclohexanone, the percent yield is increased by 8% and the
process is 24 times shorter. Grignard reagent synthesis also occurs at ambient
temperature and pressure which is favorable for industrial scaling. As shown in Table 1,
cost and production rates fall in between cyclohexanone and butadiene. It costs $920 per
ton of the Grignard reagent, but 500,000 tons of Adipic acid are produced each year with
a gradually expanding market. This explains the value increase observed in Figure 1.
To clarify, the observation that the Grignard reagent synthesis occurs at lower
temperatures and pressure is due to the structural differences between the reagents of
each method. For instance, the production of the Adipic acid at the lower temperature
range of 25.5-35.5 degrees Celsius in Grignard chemistry comes from the reactivity of
15
the carboxyl group on the Grignard reagent. A carboxyl group requires less energy and
temperature to react with another molecule compared to a ringed or alkene functional
group. On the other hand, the cyclohexanone has a ringed structure with a carbonyl
attached to it. This requires more energy and pressure (11 bar) in order to produce Adipic
acid.7 Despite needing more strenuous conditions, the use of cyclohexanone is one of the
most common methods to produce Adipic acid and currently is one of the cheapest and
most productive methods for Adipic acid out of all three of them. As for the newer
method of using butadiene, the reaction requires a multiple step synthesis. This makes it
more challenging to synthesize and leads to higher costs of production with lower yields.
Therefore, this decrease in temperature and pressure due to the use of reactive Grignard
reagents shows the possibility of allowing companies to cheaply and more effectively
produce Adipic acid at a rate that is similar to very common methods for Nylon 6-6
production, such as cyclohexanone.
This rate of Adipic acid production through Grignard synthesis not only allows
for a competitive production of Adipic acid and the further synthesis of Nylon 6-6, but
also allows for a decrease in the level of atmospheric CO2. With a twenty minute reaction
time, multiple reactions can happen hourly compared to the 8 hour minimum reaction
time of cyclohexanone. This process would utilize CO2 in a 1:1 ratio with 1-4 butanediol
which would lead to quick and effective turnovers of atmospheric CO2 into Adipic acid.
Furthermore, with the highest efficiency and quickest reaction process, the use of CO2 in
Grignard syntheses seems like the best method for the future production of Adipic acid
and the further production of Nylon 6-6.
16
Conclusion
In this experiment, the production of Adipic acid was produced through the
innovative method using a Grignard reaction between CO2 and 1,4-butanediol. When
compared to the most popular type of reaction, synthesis via cyclohexanone, the Grignard
reagent produced the highest yield of Adipic acid in the quickest amount of time. With
the low cost per ton, this suggests that the Grignard reagent synthesis is the most efficient
method for production of Adipic acid and can lead to more cheap, eco-friendly means of
Nylon 6-6 production.
The main finding of this experiment concludes that we can use captured CO2 from
the atmosphere and utilize it to produce Nylon 6-6 which has many different applications
in machinery parts and textiles. This allows for the turnover of harmful greenhouse
gasses into commercialized products. To further this study, we will be experimenting
with other green reagents to optimize the use of CO2 utilization and the overall
production of Nylon 6-6. Our study has shown high yields and purities but many other
methods of Nylon production should be further examined.
Supplementary Material Available
The appendix contains a more detailed description of the process and preparation
of Adipic acid. H-NMR of the substrate are shown and discussed. The FTIR of the
substrates required for Nylon 6-6 synthesis are found in the appendix as well.
References
[1] Van de Vyver, S.; Roman-Leshkov, Y. Emerging catalytic processes for the
production of Adipic acid. Catal. Sci. Technol. 2013, 3, 1465-1479.
17
[2] Dowson, G. R. M.; Dimitriou, I.; Owen, R. E.; Reed, D. G.; Allen, R. W. K.; Styring,
P. Kinetic and economic analysis of reactive capture of dilute carbon dioxide with
Grignard reagents. Faraday Discuss., 2015, 183, 47-65.
[3] Kent, J. A. Manufactured Textile Fibers. Kent and Riegel's Handbook of Industrial
Chemistry and Biotechnology; Springer Science & Business Media: 2010; Volume 1,
454-456.
[4] Alger, M. Polymer Science Dictionary; Springer Science & Business Media: 1996;
241.
[5] Condensation Polymerization.
https://www.materialsworldmodules.org/resources/polimarization/4-condensation.html
(accessed April 2, 2017).
[6] Adipic Acid GPS Safety Summary; Rhodia: 2012; 1-6.
[7] Tamura, M.; Ito, K.; Honda, M.; Nakagawa, Y.; Sugimoto, H.; Tomishige, K. Direct Copolymerization of CO2 and Diols. Sci. Rep. 2016, 6, 24038.
S1
Supporting Information
The Synthesis of Adipic Acid through CO2 Utilization to Produce Nylon 6-6
Allison Eckert, Christopher Gusmano, and Dillon James
Department of Chemistry, University of Missouri-Columbia, Columbia, Missouri, 65201
Email: [email protected] ; [email protected] ;
mailto:[email protected]:[email protected]:[email protected]
S2
Table of Contents
Grignard Reactions………………………………………………………………....S3
1H-NMR of Adipic Acid…………………………………….……………………...S5
IR Spectra of Nylon and Components………………………………………….…..S6
Bibliography …………………………………………………………………….....S7
S3
Grignard reactions such as the synthesis of Adipic acid are tracked by the titration
of the reagent using 1,10-phenanthroline of 99.5% purity. A color change indicates the
formation of a charge transfer complex with the reagent in a 1:1 molar ratio which is then
titrated by using 2-butanol of 99% purity. For the reaction of butane-1,4-dimagnesium
chloride and CO2, no color change occurred 1,10-phenanthroline in dry THF was injected
into solution. To determine the rate of reaction of CO2 with butane-1,4-dimagnesium
chloride, a high-accuracy pressure transducer measured CO2 consumption. The pressure
drop was monitored intermittently between sparging CO2 to encourage stability. Carbon
dioxide gas was bubbled through the Grignard reagent solution. This reaction with CO2
was assumed to also be quantitative because of the high yields measured. Reactions were
performed under inert (N2) atmosphere. HPLC grade THF was dried. CO2 and N2 mixture
compositions were achieved using a pair of Bronkhorst 100 mL min-1 mass flow
controllers. Compressed air was dried using a Drierite™ 8 Mesh Laboratory Drying Unit.
NMR spectra were recorded using D2O. A dried 2-neck 100 mL round bottom
flask with a condenser was charged with 20 mL dried THF under nitrogen. The flask was
connected to a sparging needle. A flow of 100 mL min-1 of CO2 gas was vented through
a silicone oil bubbler. To avoid water condensation during preparation, gas flowed
through the apparatus for 20 minutes before a salt-ice slurry was added. The apparatus
was set in an ice bath and allowed 30 minutes to chill. 3 M butane-1,4-dimagnesium
chloride was added to the vessel under positive nitrogen pressure. Each minute, the CO
gas flow was stopped for 10 to 20 seconds. Pressure readings were recorded every 0.2
seconds. Once there was no pressure drop being observed, the reaction was complete. 3.5
M of HCl was added until the mixture cleared was tested to be acidic. 1 M of NaOH was
added until the reaction mixture became basic and a precipitate formed. Rotary
evaporation was used to extract the precipitate from the basic liquid. The precipitate was
S4
then dried and dissolved in 2 mL of D2O and 10 mL of DMSO. DMSO was added to use
in the NMR spectroscopy.
The NMR spectra showed peaks at 2.81 and 1.94 ppm. The peak at 2.81 ppm was
the solvent peak, showing six hydrogens. The carboxylic acid derived hydrogens are
seen at 1.94 ppm. The integration of both peaks was used to determine the resulting
carboxylate yield of Adipic acid.
The FTIR of Adipic acid shows peaks that indicate the carboxylic acid dimers at
1700 cm-1. The alcohol is seen broadly around 3000 cm-1. Carbon hydrogen bonds are
seen at a much more acute peak at 2800 cm-1.
The Nylon 6-6 salt has alcohol and carbon hydrogen bond stretches similar to
those on the FTIR of Adipic acid. The FTIR of Nylon 6-6 shows combinations of the
stretches seen in Adipic acid and hexamethylenediamine.
S5
Figure S1. 1H-NMR of Adipic Acid
S6
Figure S2. FTIR Spectra of Nylon 6-6 and Components
S7
Table S2. Characteristic data of substrate Adipic Acid
.
S8
Bibliography
Dowson, G. R. M.; Dimitriou, I.; Owen, R. E.; Reed, D. G.; Allen, R. W. K.; Styring, P.
Kinetic and economic analysis of reactive capture of dilute carbon dioxide with Grignard
reagents. Faraday Discuss., 2015, 183, 47-65.
AIST : Spectral Database for Organic Compounds,
SDBS. http://sdbs.db.aist.go.jp/sdbs/cgi-bin/direct_frame_top.cgi (accessed March 24,
2017).
Lee Ware, S.; Gaunt, C. Adipic acid to nylon 6-6: a two-step process.
https://leeware.wordpress.com/2010/12/31/Adipic-acid-to-nylon-6-6-a-two-step-process/
(accessed March 24, 2017).
Deng, Y.; Ma, L.; Mao, Y. Biological Production of Adipic Acid from Renewable
Substrates: Current and Future Methods. Biochem. Eng. J. 2016, 105, 16-26.
Vyver, Stijn Van De, and Yuriy Román-Leshkov. "Emerging catalytic processes for the
production of Adipic acid." Catalysis Science & Technology. Royal Society of
Chemistry, 30 Jan. 2013. Web. 03 Apr. 2017.
Zhang, S.; Jiang, H.; Gong, H.; Sun, Z. “Green Catalytic Oxidation of Cyclohexanone to
Adipic Acid.” Petroleum Science and Technology. Department of Materials Science,
2003. Web 01 Apr. 2017.
http://sdbs.db.aist.go.jp/sdbs/cgi-bin/direct_frame_top.cgi