www.sciencemag.org/content/346/6216/1495/suppl/DC1

Supplementary Materials for

One-pot room-temperature conversion of cyclohexane to adipic acid by

ozone and UV light

Kuo Chu Hwang* and Arunachalam Sagadevan

*Corresponding author. E-mail: kchwang@mx.nthu.edu.tw

Published 19 December 2014, Science 346, 1495 (2014)

DOI: 10.1126/science.1259684

This PDF file includes:

Materials and Methods

Supplementary Text

Figs. S1 to S6

Tables S1 to S15 1H and

13C NMR Data

1H and

13C NMR Spectra

Full Reference List

Materials and Methods

General procedure for oxidative C-H functionalization of cycloalkanes.

All reactions were conducted under an ozone atmosphere using oven-dried glass

wares. A 100 W Hg lamp was used as the light source without any filter. Ozone was

generated by an ozone generator (C-labsky series, model no. c-l010-DT)) using pure

oxygen gas as the source of oxygen. Starting materials (Aldrich) are commercially

available and were used as received. NMR spectra were recorded in CDCl3, DMSO or

CDCl3-DMSO mixture, 1H NMR at 600 MHz and

13C NMR at 150 MHz were used to

determine the structures of products. Data were reported as: s= singlet, d= doublet, t=

triplet, q= quartet, m= multiplet, b= broad.

A dry test tube of 20 mL capacity was charged with cyclohexane (6.5 mL) and

equipped with a Teflon septum and a magnetic stirrer bar. Ozone gas (flow rate= 0.45

mL per minute) was bubbled into the cyclohexane solution and simultaneously irradiated

under a 100 W Hg lamp (200 mW/cm2 at 310 nm) (distance between reaction vessel and

light is 5 cm) for 0.5-15 h at room temperature. The reaction vessel was equipped with

chilled water-methanol circulator (-5 to -10 oC) condenser to trap evaporating

reactants/intermediates and to improve the mass balance. Upon irradiation, white solid

was slowly formed and precipitated. After completion of reaction the crude product

(pasty wet solid) was collected and subjected to isolation/purification of the process. The

white solid was further dispersed in ethyl acetate-hexane (20:80) solution and stirred for

30 min at room temperature. The solid precipitate was collected by centrifugation and

dried under vacuum for 2 h at room temperature. Small amount of the collected dried

solid product was dissolved in d-chloroform for 1H NMR and

13C NMR measurements to

identify the reaction products and the purity of adipic acid. In 1H NMR, a quite clean

adipic acid spectrum was observed without the presence of cyclohexane, cyclohexanol

and cyclohexanone peaks. To be very cautious for the structure characterization, we

further grew crystals of the white solid precipitate in ethanol and adopted x-ray

crystallography for structure characterization of the solid precipitate product, since x-ray

crystallography is an absolute method for structure characterization of an unknown

compound. For recrystallization of the solid precipitate, 6.5 g of the solid dried

precipitate was added to 32 mL of absolute ethanol. The solid-ethanol solution was

slowly heated to refluxing condition and continued stirring for 30 minutes. Then, heater

was turned off to allow slow cooling of the solution to room temperature. White

crystalline solids were slowly formed. The crystalline white solids were isolated by

filtration method (6.1g). The chemical structure of the white crystalline product was

determined by single crystal x-ray chromatography to be adipic acid.

In the current photo irradiation process, liquid reactant was gradually converted to solid

precipitate. At the late stage of reaction process, a small amount of liquid

reactant/intermediates were trapped in the solid precipitate. It is therefore inherently

difficult to reach more than 90% conversion. Nevertheless, the problem can be overcome

by designing a dynamic flow reactor allowing regular removal of solid precipitated

products from the bottom of the reactor when a large scale production of solid adipic acid

is concerned.

Procedure for determination of conversion, selectivity, and mass balance.

After ozone-uv irradiation, a known amount (in mole) of external standard, 1,4-

dicyanobenzene, was added to the final crude products solution. Once the external

standard was added, the molar ratios of all products relative to the external standard in the

final solution are fixed irrespective of the later experimental procedure. Then, the

absolute amounts of all products in the final solution can be determined by multiplication

of the relative molar ratios of all crude products to the external standard (determined by

1H NMR peak area ratio) with the mole of the external standard added. Since adipic acid

was formed and precipitated as solid precipitate, DMSO and d-chloroform were used to

fully dissolve the solid adipic acid for 1H NMR measurement so that the amount of adipic

acid in the crude product can be determined accurately. The mass balance was

determined by the sum of all products (in moles, including unreacted starting substrate)

divided by the initial mole of starting material. The selectivity of adipic acid (AA) was

determined by the mole of AA in the crude product (by 1H NMR) divided by the total

moles of all crude products. The conversion percentage was determined by the total

moles of all crude products divided by the initial mole of the starting material. From 1H

NMR spectra, only cyclohexanol, cyclohexanone and adipic acid were detected as final

products. No shorter chain acids or any other decomposition products were detected in

1H NMR measurements during the time course of reaction.

Supplementary Text

General aspects: reproducibility, effects of pH, uv fluence, and ozone flow rate on

product yields. As shown in the Tables S1 and S2, all experiments were repeated at

least 3 times. The reproducibility of all experiments is within a reasonably good range.

The mass balance in the neat cyclohexane-dark system seems to be lower than others,

indicating that the -5 to -10 oC cooling condenser can only efficiently trap the vapors of

higher boiling point intermediates, cyclohexanol and cyclohexanone, but poorly for the

low boiling point starting cyclohexane substrate. Photo irradiation and addition of acidic

water can much more efficiently convert low boiling point cyclohexane to intermediates

(i.e., cyclohexanol and cyclohexanone) and product (i.e., adipic acid) of higher boiling

points, leading to higher adipic acid yields and higher mass balance values.

We also investigated the pH effect on the yield of adipic acid. Aqueous 0.5 M HCl or

0.5 M NaOH solution was added to the cyclohexane solution. The amount of water

added to cyclohexane solutions is 8 vol%. The results in Tables S1 and S3 show that

under the same condition, the presence of acidic water results in higher adipic acid yields

than those for both neutral and basic water systems in both light and dark conditions.

Since both ozone and singlet O(1D) can react with water to generate hydroxyl radicals,

the major oxidant switches from ozone or O(1D) to hydroxyl radical in the cyclohexane-

water systems (see below for the discussion of plausible reaction mechanisms). In the

literature, it is known that hydroxyl anion (i.e., a basic water condition) can react with

ozone molecules to generate non-hydroxyl radical product (32), and therefore disfavors

the formation of hydroxyl radical. Therefore, a low pH value will favor the formation of

more amounts of hydroxyl radical via suppression of hydroxyl radical concentration,

leading to more efficient and more rapid oxidative conversion of cyclohexane to adipic

acid and thereby higher adipic acid yield.

In the presence of acidic water and absence of uv light irradiation, one can obtain a

reasonably good yields (43~46%) of adipic acid (see Table S1). Exposure of the

cyclohexane-acidic water-ozone system to photo irradiation can further promote higher

yields (73~77%) of adipic acid and higher mass balance values under the same condition

(see Table S1). Photo irradiation will efficiently convert ozone molecules to singlet

O(1D), which can either directly react with cyclohexane/ intermediates or react with water

to generate hydroxyl radical, and thus accelerate the oxidation of cyclohexane to generate

higher boiling point intermediate (i.e., cyclohexanone, see discussion below about

reaction mechanisms). Formation of higher boiling point intermediate can better prevent

evaporation of reactants and thus higher final mass balance values.

We also investigated the effects of uv fluence and ozone flow rate on the yields of

adipic acid (see Tables S4 and S5). Higher uv light intensity will in general lead to

higher adipic acid yields and higher mass balance values. Higher ozone flow rate will in

general lead to higher adipic acid yields, and simultaneously accelerate the

reactant/intermediate evaporation rate and thus lower the mass balance values. To

compromise the pros and cons, a 0.45 mL/min flow was found to be the best for our

current reactor design.

Table-S1. Effects of water and light irradiation on the yields of adipic acid using

cyclohexane as the starting substrate. The light intensity is 200 mW/cm2 at 310 nm (with

the distance between the 100 W Hg lamp and the reactor being 5 cm. The ozone flow

rate is 0.45 mL/min. The reaction vessel was equipped with chilled water-methanol

circulator (-5 to -10 oC) condenser (to trap evaporating reactant and intermediates).

Note: 1d is cyclohexanone, and 2b is adipic acid.

Substrates Products

%Yield

2b 55

%Conversion

65

%Selectivity

for 2

851d +10

Condition No. of run

neat, rt,15h

h

4

2b 53 64 831d +115

2b 51 61 841d +106

1b

2b 13 28 461d +15neat,rt,15h

dark

1

2b 14 27 521d +132

2b 14 30 471d +163

Massbalance

65

64

61

53

55

52

2b 77 86 891d +9+ 8 vol% aqueous

0.5 M HCl, RT,

15 h, h

10

2b 74 82 901d +811

2b 73 81 901d +812

2b 45 58 781d +13+ 8 vol% aqueous 0.5 M HCl, RT, 15 h, dark

7

2b 46 56 821d +108

2b 43 50 841d +79

58

56

51

86

82

81

Table-S2. Effects of water and light irradiation on the yield of adipic acid using

cyclohexanol and cyclohexanone as the starting substrates. The light intensity is 200

mW/cm2 at 310 nm (with the distance between the 100 W Hg lamp and the reactor being

5 cm. The ozone flow rate is 0.45 mL/min. The reaction vessel was equipped with

chilled water-methanol circulator (-5 to -10 oC) condenser (to trap evaporating

reactants/intermediates). Note: 1d is cyclohexanone, and 2b is adipic acid.

Substrates Products

%Yield

2b 83

%Conversion

93

%Selectivity

for 2b

891d +10

Condition No. of run

neat,rt, 8h

h

4

2b 85 91 931d +65

2b 83 96 871d +136

2b 26 42 621d +161

2b 27 41 661d +142

2b 22 38 581d +163

Massbalance

98

97

98

96

97

98

1c

neat,rt, 8h

dark

OH

2b 88 88 991d +8neat,rt,8h

h

4

2b 92 92 991d +55

2b 89 89 991d +56

2b 28 28 991d +671

2b 34 34 991d +612

2b 27 27 991d +673

96

97

95

95

95

94

neat,rt, 8h

dark

O

1d

Table S3. pH effect on the yield of adipic acid in the cyclohexane-water-ozone-uv

irradiation system. The light intensity is 200 mW/cm2 at 310 nm with the distance

between the 100 W Hg lamp and the reaction vessel being 5 cm. The ozone flow rate is

0.45 mL/min. The reaction vessel was equipped with chilled water-methanol circulator (-

5 to -10 oC) condenser (to trap evaporating reactants/intermediates). Note: 1d is

cyclohexanone, and 2b is adipic acid.

Substrates Products

%Yield

2b 63

%Conversion

73

%Selectivity

for 2b

861d +10

Condition No. of run

+ 8 vol% neutral

H2O, RT, 15h, h

1

2b 65 73 891d +82

2b 66 73 901d +73

1b

2b 33 48 691d +15+ 8 vol% neutral

H2O, RT, 15h, dark1

2b 34 47 721d +132

2b 36 48 751d +123

Massbalance

80

78

77

55

57

58

2b 22 32 691d +10+ 8 vol% aqueous 0.5 M NaOH, RT 15 h, dark

1

2b 40 55 731d +151

58

78+ 8 vol% aqueous

0.5 M NaOH, RT

15 h, h

Table S4. Effect of uv fluorence on adipic acid yield. The ozone flow rate is 0.45 mL

per minute. The reaction vessel was equipped with chilled water-methanol circulator (-5

to -10 oC) condenser (to trap evaporating reactants). Note: 1d is cyclohexanone, and 2b

is adipic acid.

Substrates Products

%Yield

%Conversion %Selectivity for 2b

ConditionUV-light power density

(mW/cm2 at 310 nm)

(distance)

1b 2b 68 80 851d + 12

200 (5 cm) 2b 75 83 901d +8

150 (14 cm)

2b 60 73 821d +13100 (22 cm)

Massbalance

80

83

73

+ 8 vol% aqueous

0.5 M HCl,RT, 15h

h

Table S5. Effect of ozone flow rate on the yield of adipic acid. The light intensity is 200

mW/cm2 at 310 nm with the distance between the 100 W Hg lamp and the reactor being 5

cm. The reaction vessel was equipped with chilled water-methanol circulator (-5 to -10 oC) condenser (to trap evaporating reactants/intermediates). Note: 1d is cyclohexanone,

and 2b is adipic acid.

Substrates Products

%Yield %Conversion %Selectivity

for 2b

Condition O3 flow rate

(mL / minute)

1b

2b 68 73 931d + 51.0

2b 75 83 901d +80.45

Massbalance

73

83

+ 8 vol% aqueous

0.5 M HCl,RT, 15h

h

2b 55 80 691d +250.15 93

Measurements of intermediate/product concentrations during the reaction time course:

The concentrations of reactant and products were measured as a function of reaction

time course for two different systems, i.e., (a) neat cyclohexane and (b) cyclohexane-8

vol% aqueous 0.5 M HCl under ozone treatment and uv irradiation condition (see Fig.

S3(a) & S3(b) shown below). In the experiments, a constant amount of reaction solution

was removed from the bulk solution every 15 min, and added a fixed amount of 1,4-

dicyanobenzene solution as an external standard for 1H NMR determination of product

concentrations. As shown in Fig. S3(a) below, both cyclohexanol and cyclohexanone

were detected as reaction intermediates in the case of neat cyclohexane, whereas in the

presence of acidic water only cyclohexanone was detected as the primary intermediate

and no cyclohexanol was detected during the reaction time course. Such a result

indicates that the major reaction pathways might be different for these two systems. As

described in the main text for neat cyclohexane, cyclohexane was oxidized by O(1D) to

form cyclohexanol, which was further oxidized by O(1D) to generate cyclohexanone, and

then to adipic acid. This reaction scheme matches well with the observation shown in Fig.

S3(a).

When in the presence of acidic water, the variation in the concentrations of

cyclohexane and products was shown in Fig. S3(b). Cyclohexanone, instead of

cyclohexanol, was observed as the primary intermediate for oxidative conversion of

cyclohexane to adipic acid. The concentration of cyclohexanol was too low to be

detected by 1H NMR.

Reaction Mechanism for dark conversion of neat cyclohexane to adipic acid by ozone.

It was reported that ozone can abstract hydrogen atom from saturated hydrocarbons to

form [R. .OOOH] radical pair, which then collapses to form highly unstable alkyl

trioxides (ROOOH), as evidenced by low temperature (-40 C) 1H NMR (34). The RO-

OOH then decomposes to form ROH and HOOH. Ozonation of neat cyclohexane in

dark is likely to follow a similar chemical route to generate cyclohexanol. Subsequent

hydrogen atom abstraction at the weakest C-H bond adjacent to the carbonyl position by

ozone will generate ketone-alpha trioxide intermediate which, upon decomposition of the

O-O and C-C bonds, will generate acid-aldehyde. The aldehyde moiety of the acid-

aldehyde intermediate can be easily oxidized by ozone in dark to become carboxylic acid,

leading to the formation of dicarboxylic adipic acid.

Reaction Mechanism for light induced ozonolytic conversion of neat cyclohexane to

adipic acid. Upon photo irradiation, ozone molecule will decompose to generate singlet

O(1D) atom, which initiates oxidative conversion of cyclohexane to adipic acid. A

possible reaction pathway for the neat cyclohexane-ozone-uv system is proposed in Fig.

S4(i) to account for formation of adipic acid via selective C-H bond oxidation of

cyclohexane by O(1D). First, direct C-H bond insertion of O(

1D) into cyclohexane would

lead to formation of cyclohexanol (21), which is further oxidized by O(1D) at the weakest

methine C-H bond to form a geminal diol, 1,1’-dihydroxycyclohexane. Geminal diols are

known to be very unstable and will rapidly undergo dehydration to form stable ketones

(22). The bonding energies of methine C-H, methylene C-H, and O-H bonds are ca. ~96,

~99, and ~105 kcal/mol, respectively (23). Insertion of O(1D) into a C-H bond in

cyclohexane requires cleavage of one C-H bond and formation of two bonds (i.e., C-O

and O-H), which is exothermic and thermodynamically favored. Subsequent insertion of

O(1D) into the methine C-H bond of cyclohexanol is also thermodynamically favored.

Both cyclohexanol and cyclohexanone were isolated as stable intermediates upon short

time uv irradiation of cyclohexane in the presence of ozone. The conversion of

cyclohexanone to adipic acid by reaction with singlet O(1D) atom probably proceeds via

di-hydroxylation at the alpha C-H bond adjacent to the ketone functionality, since the

alpha C-H bond is weaker than other remote methylene C-H bonds. Decomposition of

the 1,1’-dihydroxycyclohexanone may undergo different pathways (paths a and b) to

generate two possible intermediates, i.e., 1-formyl hexanoic acid and

cyclohexanediketone (see Fig. S4(i)). Control experiments show that 1-formyl hexanoic

acid (2.3 M in CCl4) can be quantitatively converted to adipic acid within 20 min. upon

ozone treatment and uv irradiation at room temperature, whereas under the same

condition cyclohexanediketone was converted to pentanedioic acid, instead of adipic acid

(path b). The control experiments suggest that the conversion of cyclohexane,

cyclohexanol, and cyclohexanone to adipic acid likely occurs via the pathway a.

Alternatively, cyclohexanone may undergo tautomerization to become the enol form (see

the path c in Fig. S4(i)), which can then react with ozone in the dark to generate adipic

acid. The above scheme is supported by kinetic measurements of intermediate/product

concentrations during the reaction time course (see Fig. S3(a) and discussion above).

Reaction mechanisms for cyclohexane-acidic water-ozone-uv irradiation reaction.

Both ozone and O(1D) (generated by uv irradiation of ozone) are reported to react with

water to form hydroxyl radical (.OH) (see, equations 3 & 4 in Fig. S4(ii))(24, 25)

Hydroxyl radical is known to abstract hydrogen atoms from various hydrocarbons with

slow rates (~5 x 107 M

-1s

-1) in dipolar and aprotic solvents (33), and initiate peroxidation

chain reaction in the presence of molecular oxygen to generate hydroperoxides (34). It is

possible that hydroxyl radical abstracts a hydrogen atom from cyclohexane to generate

cyclohexyl radical, which then reacts with molecular oxygen, followed by hydrogen atom

abstraction from another cyclohexane molecule, and to produce cyclohexyl

hydroperoxide (see equation (5) in Fig. S4(ii)). The cyclohexyl hydroperoxide, unstable

in the presence of trace amounts of metal ions, could then decompose to generate

cyclohexanone directly as the primary product without forming cyclohexanol. Selective

hydrogen atom abstraction of hydroxyl radical toward cyclohexanone at the weakest

alpha C-H position adjacent to the carbonyl group will lead to formation of alpha-keto

hydroperoxide, which decomposes to generate carboxylic acid-aldehyde, and then to

adipic acid upon air or ozone oxidation of the aldehyde moiety (see equation (6) in Fig.

S4(ii)).. The above proposed reaction scheme for hydroxyl radical-mediated oxidative

conversion of cyclohexane to cyclohexanone, and finally to adipic acid was supported by

the variation in the concentrations of cyclohexane, cyclohexanone and adipic acid during

the reaction time course (see data in Fig. S3(b)). The presence of hydroxyl radical in

cyclohexane-acidic water-ozone-uv irradiation system was confirmed by EPR

measurements (see the EPR data in Fig. S5). Besides the above proposed mechanisms,

the possibility of having other (minor) reaction pathways is not excluded.

EPR measurements of hydroxyl radicals:

EPR spectra (X band, 9.8 GHz, room temperature) were taken from samples of

cyclohexane-5 vol% aqueous 0.5 M HCl under ozone bubbling and uv light irradiation

(by 100 W Hg lamp irradiation) in the presence a radical trapping reagent, 5,5-Dimethyl-

1-pyrroline-N-oxide (DMPO, 2.5 x 10-2

M). The parameters used in the simulation are

the followings: g= 2.0070, coupling constant AN= 7.2 G, and ArH= Ar’H= 4.1 G. All

measurements were done at room temperature. By using DMPO as a spin trapping

reagent, we have detected the presence of hydroxyl radical (see the EPR spectra shown

below in Fig. S5) in both dark and photo conditions in the case of cyclohexane-acidic

water-ozone system. The observed EPR spectra for both light and dark conditions match

well with the simulated spectrum and are also the same as those reported in the literature,

where the hydroxyl radical-DMPO adduct was oxidized (possibly by ozone) to become

DMPOX (35). (No EPR signal was detected in neat cyclohexane-ozone system in both

dark and light conditions.).

Pros and Cons of four different reaction processes. In the manuscript, we are reporting

four different processes for the synthesis of adipic acid, namely, (a) neat cyclohexane-

ozone-dark, (b) neat cyclohexane-ozone-light, (c) cyclohexane-acidic water-ozone-dark,

and (d) cyclohexane-acidic water-ozone-light (see results in Table S1). The advantage of

the process (a) is simple, but the adipic acid yield is too low and the mass balance is also

quite low, which is due to easy evaporation of low boiling point of cyclohexane by the

ozone gas flow. Photo irradiation of the neat cyclohexane-ozone system (i.e., the process

(b)) can dramatically improve the adipic acid yield to ~50 mol%, and also improve the

mass balance. The disadvantage of the process (b) is that it requires a photo irradiation

setup and additional photo-electricity consumption. Addition of acidic water to neat

cyclohexane in the dark (i.e., the process (c)) is very promising process for synthesis of

adipic acid, since this process can generate ~45 mol% of adipic acid, approaching to that

obtained by photo irradiation of neat cyclohexane-ozone system (i.e., the process (b)), but

without the need of additional photo-electricity consumption. The process (c) is better

than both the processes (a) and (b) in terms of simplicity and the adipic acid yield. The

disadvantages of the process (c) are that the adipic acid yield is below 50 mol% and

nearly 40 mol% of starting substrate/intermediates was lost via evaporation.

Combination of acidic water and photo irradiation (i.e., the process (d)) leads to the

highest adipic acid yield (~75 mol%) and the highest mass balance value (~82 mol%)

among all. The disadvantage of this process is the same as that for the process (b), that is,

the need for additional photo irradiation setup and photo-electricity consumption. In

general, the electricity-to-light conversion efficiency is low, 10~15%, for high pressure

Hg lamp, but 30% for uv LEDs. If uv LEDs were used as the light source, the increase

in the production cost of the process (d) over the process (c) may not be a true

disadvantage. Overall, the process (d) will provide faster production and lower cost for

production of adipic acid. since the ~ 1.67 fold increase in the adipic acid yield under the

same experimental condition and operation time is quite significant.

Fig. S1.

Ozonolytic conversion of cyclohexane to adipic acid under uv photo irradiation.

Fig. S2

ORTEP diagram of the solid product (2b) isolated from the cyclohexane-O3-uv

irradiation system.

Table S6. Crystal data and structure refinement for TWIN5.

Identification code twin5

Empirical formula C6 H10 O4

Formula weight 146.14

Temperature 100(2) K

Wavelength 0.71073 Å

Crystal system Monoclinic

Space group P 21/c

Unit cell dimensions a = 7.1627(10) Å

b = 5.1358(7) Å

c = 9.9772(18) Å

Volume 343.08(9) Å3

Z 2

Density (calculated) 1.415 Mg/m3

Absorption coefficient 0.120 mm-1

F(000) 156

Crystal size 0.30 x 0.25 x 0.25 mm3

Theta range for data collection 3.042 to 26.411°.

Index ranges -8<=h<=8, 0<=k<=6, 0<=l<=12

Reflections collected 689

Independent reflections 689 [R(int) = ?]

Completeness to theta = 25.242° 99.8 %

Absorption correction Semi-empirical from equivalents

Max. and min. transmission 0.9485 and 0.6857

Refinement method Full-matrix least-squares on F2

Data / restraints / parameters 689 / 0 / 48

Goodness-of-fit on F2 1.242

Final R indices [I>2sigma(I)] R1 = 0.0444, wR2 = 0.1188

R indices (all data) R1 = 0.0465, wR2 = 0.1194

Extinction coefficient n/a

Largest diff. peak and hole 0.290 and -0.226 e.Å-3

Table S7. Atomic coordinates ( x 104) and equivalent isotropic displacement

parameters (Å2x 103) for TWIN5. U(eq) is defined as one third of the trace of the

orthogonalized Uij tensor.

________________________________________________________________________

x y z U(eq)

________________________________________________________________________

C(1) 3297(4) 9097(5) 8088(3) 20(1)

C(2) 2092(4) 8365(6) 6573(3) 21(1)

C(3) 509(4) 10346(5) 5790(3) 21(1)

O(1) 4778(3) 7483(4) 8697(2) 27(1)

O(2) 2937(3) 10982(4) 8693(2) 26(1)

Table S8. Bond lengths [Å] and angles [°] for TWIN5.

_____________________________________________________

C(1)-O(2) 1.216(3)

C(1)-O(1) 1.313(3)

C(1)-C(2) 1.498(3)

C(2)-C(3) 1.517(4)

C(2)-H(2A) 0.9900

C(2)-H(2B) 0.9900

C(3)-C(3)#1 1.525(5)

C(3)-H(3A) 0.9900

C(3)-H(3B) 0.9900

O(1)-H(1) 0.8400

O(2)-C(1)-O(1) 123.5(2)

O(2)-C(1)-C(2) 123.5(2)

O(1)-C(1)-C(2) 112.9(2)

C(1)-C(2)-C(3) 114.1(2)

C(1)-C(2)-H(2A) 108.7

C(3)-C(2)-H(2A) 108.7

C(1)-C(2)-H(2B) 108.7

C(3)-C(2)-H(2B) 108.7

H(2A)-C(2)-H(2B) 107.6

C(2)-C(3)-C(3)#1 111.8(3)

C(2)-C(3)-H(3A) 109.3

C(3)#1-C(3)-H(3A) 109.3

C(2)-C(3)-H(3B) 109.3

C(3)#1-C(3)-H(3B) 109.3

H(3A)-C(3)-H(3B) 107.9

C(1)-O(1)-H(1) 109.5

_____________________________________________________________

Symmetry transformations used to generate equivalent atoms: #1 -x,-y+2,-z+1

Table S9. Anisotropic displacement parameters (Å2x 103) for TWIN5. The

anisotropic displacement factor exponent takes the form: - 2[ h2 a*2U11 + ... + 2 h k

a* b* U12 ]

________________________________________________________________________

U11 U22 U33 U23 U13 U12

________________________________________________________________________

C(1) 19(1) 23(1) 18(1) 0(1) 6(1) -2(1)

C(2) 22(1) 22(1) 16(1) -3(1) 5(1) -2(1)

C(3) 22(1) 23(1) 18(1) -3(1) 5(1) 0(1)

O(1) 27(1) 31(1) 17(1) -6(1) 0(1) 7(1)

O(2) 26(1) 30(1) 18(1) -6(1) 2(1) 6(1)

________________________________________________________________________

Table S10. Hydrogen coordinates ( x 104) and isotropic displacement parameters (Å2x

10 3) for TWIN5.

________________________________________________________________________

x y z U(eq)

________________________________________________________________________

H(2A) 1434 6672 6576 25

H(2B) 3008 8131 6037 25

H(3A) 1134 12086 5869 26

H(3B) -507 10434 6250 26

H(1) 5457 8030 9520 41

________________________________________________________________________

Fig. S3

Concentrations of cyclohexane, cyclohexanol, cyclohexanone, and adipic acid as a

function of reaction time in (a) neat cyclohexane, and (b) cyclohexane-8 vol% aqueous

0.5 M HCl-ozone-uv irradiation at room temperature. The solid lines are smooth

interpolation between data points.

O3 100 W Hg lamp

HO

hv

O3

H HOH

O

HOH

O

O

HOOH

O

O

OO

OH

(isolated)(isolated)

O (1D) +

1O2

O(1D)

O(1D)

H

O(1D)

OOH

H

OH

OOH

X

HO

O O

OHO3

- CO2

path a

path b

O3

OH

O

OHO OH

path c

O3 (in dark)

O (1D) +

H2O 2

.OH

O3 + H2O

(1)

(2)

(3)

2 .OH + O2

.OH

O2

(4)

O

- H2O

O

HO OH HO H

O

OHO

OHO

O.OH/O2

O3

(5)

(ii) cyclohexane-H2O-O3-uv

(i) neat cyclohexane-O3-uv

O

.

O-O.

OOH

(6)

- H2O

Fig. S4

Plausible reaction mechanisms for oxidative conversion of (i) neat cyclohexane and (ii)

cyclohexane-8 vol% aqueous 0.5 M HCl to adipic acid under uv photo-irradiation.

Fig. S5

EPR spectra detected from a cyclohexane-acidic water-ozone system under uv light

irradiation (top) and in dark (middle). The bottom EPR spectrum is a simulated one

using the following parameters: g= 2.0070, coupling constant AN= 7.2 G, and ArH= Ar’H=

4.1 G. The top equation illustrates the reaction of a spin trapping reagent, DMPO, with

hydroxyl radical, followed by ozone oxidation of the DMPO-OH adduct to become stable

DMPOX radical, which is responsible for the observed EPR signal. The observed

hydroxyl radical EPR spectra are the same as those reported in the literature (35)

Fig. S6

ORTEP diagram of the solid product (compound 2g) isolated from the cycloheptane-O3-

uv irradiation system

Table S11. Crystal data and structure refinement for 140404LT_0m.

Identification code 140404LT_0m

Empirical formula C7 H12 O4

Formula weight 160.17

Temperature 100(2) K

Wavelength 0.71073 Å

Crystal system Monoclinic

Space group C 2/c

Unit cell dimensions a = 17.7023(8) Å a= 90°.

b = 4.7139(2) Å b= 106.831(2)°.

c = 9.6336(4) Å g = 90°.

Volume 769.46(6) Å3

Z 4

Density (calculated) 1.383 Mg/m3

Absorption coefficient 0.113 mm-1

F(000) 344

Crystal size 0.30 x 0.28 x 0.13 mm3

Theta range for data collection 4.378 to 26.388°.

Index ranges -22<=h<=20, -5<=k<=4, -11<=l<=12

Reflections collected 3239

Independent reflections 779 [R(int) = 0.0196]

Completeness to theta = 25.242° 98.9 %

Absorption correction Semi-empirical from equivalents

Max. and min. transmission 0.9485 and 0.8755

Refinement method Full-matrix least-squares on F2

Data / restraints / parameters 779 / 0 / 54

Goodness-of-fit on F2 1.118

Final R indices [I>2sigma(I)] R1 = 0.0303, wR2 = 0.0812

R indices (all data) R1 = 0.0315, wR2 = 0.0823

Extinction coefficient n/a

Largest diff. peak and hole 0.338 and -0.184 e.Å-3

(2g)

O

OH

O

HO

Table S12. Atomic coordinates ( x 104) and equivalent isotropic displacement

parameters (Å2x 103) for 140404LT_0m. U(eq) is defined as one third of the trace of

the orthogonalized Uij tensor.

________________________________________________________________________ x y z U(eq)

________________________________________________________________________

O(1) 7576(1) 10484(2) 3876(1) 16(1)

O(2) 8358(1) 6734(2) 4685(1) 16(1)

C(1) 8217(1) 8953(2) 3999(1) 13(1)

C(2) 8767(1) 10305(2) 3269(1) 17(1)

C(3) 9393(1) 8373(2) 2977(1) 15(1)

C(4) 10000 10126(3) 2500 14(1)

________________________________________________________________________

Table S13. Bond lengths [Å] and angles [°] for 140404LT_0m.

_____________________________________________________

O(1)-C(1) 1.3214(12)

O(1)-H(1) 0.890(15)

O(2)-C(1) 1.2237(13)

C(1)-C(2) 1.4984(13)

C(2)-C(3) 1.5221(14)

C(2)-H(4) 0.9900

C(2)-H(5) 0.9900

C(3)-C(4) 1.5278(12)

C(3)-H(3) 0.9900

C(3)-H(2) 0.9900

C(4)-C(3)#1 1.5278(12)

C(4)-H(6) 0.9900

C(4)-H(7) 0.9900

C(1)-O(1)-H(1) 110.2(9)

O(2)-C(1)-O(1) 123.39(9)

O(2)-C(1)-C(2) 123.99(9)

O(1)-C(1)-C(2) 112.56(9)

C(1)-C(2)-C(3) 116.06(9)

C(1)-C(2)-H(4) 108.3

C(3)-C(2)-H(4) 108.3

C(1)-C(2)-H(5) 108.3

C(3)-C(2)-H(5) 108.3

H(4)-C(2)-H(5) 107.4

C(2)-C(3)-C(4) 110.17(9)

C(2)-C(3)-H(3) 109.6

C(4)-C(3)-H(3) 109.6

C(2)-C(3)-H(2) 109.6

C(4)-C(3)-H(2) 109.6

H(3)-C(3)-H(2) 108.1

C(3)-C(4)-C(3)#1 114.50(12)

C(3)-C(4)-H(6) 108.6

C(3)#1-C(4)-H(6) 108.6

C(3)-C(4)-H(7) 108.6

C(3)#1-C(4)-H(7) 108.6

H(6)-C(4)-H(7) 107.6

_____________________________________________________________

Symmetry transformations used to generate equivalent atoms: #1 -x+2,y,-z+1/2

Table S14. Anisotropic displacement parameters (Å2x 103) for 140404LT_0m. The

anisotropic displacement factor exponent takes the form: -2p2[ h2 a*2U11 + ... + 2 h k

a* b* U12 ]

________________________________________________________________________

U11 U22 U33 U23 U13 U12

________________________________________________________________________

O(1) 14(1) 17(1) 22(1) 3(1) 11(1) 2(1)

O(2) 15(1) 17(1) 20(1) 3(1) 9(1) 1(1)

C(1) 12(1) 16(1) 13(1) -3(1) 5(1) -1(1)

C(2) 15(1) 16(1) 22(1) 4(1) 11(1) 2(1)

C(3) 14(1) 16(1) 19(1) 0(1) 10(1) 0(1)

C(4) 12(1) 15(1) 17(1) 0 8(1) 0

________________________________________________________________________

Table S15. Hydrogen coordinates ( x 104) and isotropic displacement parameters (Å2x

10 3) for 140404LT_0m.

________________________________________________________________________

x y z U(eq)

________________________________________________________________________

H(4) 9037 11906 3878 20

H(5) 8448 11107 2333 20

H(3) 9140 6993 2208 18

H(2) 9660 7300 3867 18

H(6) 10283 11367 3314 17

H(7) 9717 11367 1686 17

H(1) 7291(8) 9730(30) 4409(15) 21

________________________________________________________________________

Spectroscopic Data:

Glutaric acid (2a)(36) (CAS No.: 110-94-1)

White solid; 1H NMR (600 MHz, DMSO): δ 12.019 (b, 2 H), 2.230-2.123 (m, 4 H),

1.677-1.627 (m, 2 H); 13

C NMR (150 MHz, DMSO): δ 174.2, 32.8 and 20.0. NMR data

is in agreement with authentic commercially available sample.

Adipic acid (2b)(36, 37) (CAS No.: 124-04-9)

White solid; 1H NMR (600 MHz, CDCl3-DMSO): δ 2.246-2.224 (m, 4 H), 1.603-

1.580 (m, 4 H); 13

C NMR (150 MHz, CDCl3-DMSO): δ 175.1, 33.2, and 23.8.

NMR data is in agreement with authentic commercially available sample

Pimelic acid (heptanedioic acid) (2e)(36, 38) (CAS No.: 111-16-0)

White solid; 1H NMR (600 MHz, CDCl3-DMSO): δ 2.148-2.111 (m, 4 H), 1.491-

1.440 (m, 4 H), 1.244-1.93 (m, 2 H); 13

C NMR (150 MHz, CDCl3-DMSO): δ

175.9, 33.5, 28.2, and 24.1. NMR data is in agreement with authentic commercially

available sample.

Suberic acid (octanedioic acid) (2f)(36, 39) (CAS No.: 505-48-6)

White solid; 1H NMR (600 MHz, CDCl3): δ 2.133 (t, J= 7Hz, 4 H), 1.484-1.460

(m, 4 H), 1.221-1.197 (m, 4 H); 13

C NMR (150 MHz, CDCl3-DMSO): δ 175.9,

33.7, 28.4 and 24.3. NMR data is in agreement with authentic commercially available

sample.

6-oxoheptanoic acid (3g)(40, 41) (CAS No.: 3128-07-2)

White solid; 1H NMR (400 MHz, CDCl3): δ 2.456-2.433 (m, 2H), 2.363-2.339 (m,

2 H), 2.130 (s, 3H), 1.621-1.598 (m, 4H); 13

C NMR (100 MHz, CDCl3): δ 208.6,

178.5, 43.1,33.5, 29.8, 24.0 and 23.0. NMR data is in agreement with authentic

commercially available sample.

6-oxooctanoic acid (3h)(42) (CAS No.: 4233-57-2)

White solid; 1H NMR (600 MHz, CDCl3): δ 2.394-2.382 (m, 2H), 2.369-2.300 (m,

4H), 1.584-1.561 (m, 4H), 0.993 (t, J= 7.2 Hz, 3H); 13

C NMR (150 MHz, CDCl3):

δ 211.5, 179.6, 41.7, 35.8, 33.7, 24.0, 23.0 and 7.7.

Cyclodecane-1,6-dione (2i)

White solid; 1H NMR (400 MHz, CDCl3): δ 2.42-2.31 (t, 2H), 2.31-2.20 (m, 2H),

2.0 (s, 3H), 1.50-153 (m, 4H); 13

C NMR (100 MHz, CDCl3): δ 209.0, 176.3,

43.10, 33.6, 29.7, 24.0, 22.9 33.4, 24.1; HRMS calcd for C7H12O3: 144.0786,

found: 144.0780.

3,4-dihydronaphthalen-1(2H)-one (2j)(43) (CAS No.: 529-34-0)

Brown liquid; 1H NMR (400 MHz, CDCl3): δ 8.003 (d, J= 7.8 Hz, 1H), 7.435 (t,

J= 15 Hz, 1 H), 7.272 (t, J= 15 Hz, 1 H), 7.226 (t, J= 15.6 Hz, 1 H), 2.936 (t, J= 12

Hz, 2 H), 2.626 (t, J= 13.2 Hz, 2 H), 2.130-2.088 ( m, 2 H); 13

C NMR (100 MHz,

CDCl3): δ 198.2, 144.4, 133.3, 132.5, 128.6, 127.0, 126.5, 39.0, 29.6 and 23.2.

NMR data is in agreement with authentic commercially available sample.

2,3-dihydro-1H-inden-1-one (2k)(44) (CAS No.: 83-33-0)

Brown solid; 1H NMR (600 MHz, CDCl3): δ 7.698 (d, J=7.8 Hz, 1 H), 7.530 (t, J=

15 Hz, 1 H), 7.424 (d, J= 7.8 Hz, 1H), 7.310 (t, J= 13.8 Hz, 1 H), 3.085 (t, J= 12

Hz, 2 H), 2.636-2.616 (m, 2 H); 13

C NMR (150 MHz, CDCl3): δ 206.8, 155.0,

136.9, 134.4, 127.1, 126.5, 123.5, 36.0 and 25.6. NMR data are in agreements with

commercially available authentic samples.

(2g)

O

OH

O

HO

(2g)

O

OH

O

HO

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