Allison Eckert

Undergraduate Researcher

Telephone: (618) 975-3099

Email: ajen9c@mail.missouri.edu

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:ajen9c@mail.missouri.edu

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: ajen9c@mail.missouri.edu ; dwjp88@mail.missouri.edu ;

cjgvz2@mail.missouri.edu

mailto:ajen9c@mail.missouri.edumailto:dwjp88@mail.missouri.edumailto:cjgvz2@mail.missouri.edu

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: ajen9c@mail.missouri.edu ; dwjp88@mail.missouri.edu ;

cjgvz2@mail.missouri.edu

mailto:ajen9c@mail.missouri.edumailto:dwjp88@mail.missouri.edumailto:cjgvz2@mail.missouri.edu

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