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Oxidative cleavage of long-chain terminal alkenes to carboxylic acids Dariusz Pyszny, Tomasz Piotrowski, and Beata Orlinska Org. Process Res. Dev., Just Accepted Manuscript • DOI: 10.1021/acs.oprd.8b00368 • Publication Date (Web): 21 Feb 2019 Downloaded from http://pubs.acs.org on February 21, 2019

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Organic Process Research & Development

Oxidative cleavage of long-chain terminal alkenes to carboxylic acids Dariusz Pyszny, Tomasz Piotrowski, Beata Orlińska* Department of Chemical Organic Technology and Petrochemistry, Silesian University of Technology, Krzywoustego 4, 44-100 Gliwice, Poland

ACS Paragon Plus Environment

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Table of Contents graphic


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ABSTRACT Oxidation of aliphatic terminal alkenes having more than 30 carbon atoms to carboxylic acids is presented. Such long carboxylic acids are useful as waxes, lubricants, plasticizers, etc. The oxidation was conducted in solvent-free conditions or with a small amount of diluents (heptane, methylcyclohexane, and tert-butylbenzene). Hydrogen peroxide was used as the oxidant, and tungstic acid was used as the catalyst. Halogen-free quaternary ammonium salts were used as phase transfer catalysts, and the importance of the elimination of halide ions is discussed. Purification of the crude oxidized product and tungsten removal is also presented. The product has a maximum acid number of 75 mg KOH/g, a saponification number of 100 mg KOH/g and tungsten content below 400 ppm. KEYWORDS Oxidative cleavage, α-olefins, hydrogen peroxide, phase transfer catalysis. INTRODUCTION The oxidative cleavage of alkenes into aldehydes, ketones and carboxylic acids is a reaction of both commercial and synthetic interest 1. There are many ways to cleave the olefinic C=C double bond to obtain carboxylic acids. Different types of oxidants and catalysts have been used. Old-fashioned stoichiometric oxidants, such as KMnO4, Cr(VI) compounds, and OsO4+NaIO4 (Lemieux–Johnson protocol), are toxic and/or generate many by-products and their industrial applications are limited. Methods that use, Oxone 2, 3, PhI(OAc)2 4 have also been widely employed; however, these oxidants are quite expensive. Tert-butylhydroperoxide has been successfully used as oxidant in the C=C bond cleavage reaction of aromatic olefins together with suitable catalysts (Mn-MIL-100 5, Neocuproine with Cu ions 6, FeCl3.6H2O 7, InCl3 8, Ag/Au nanoparticles 9). However tertbutylhydroperoxide generally does not react with aliphatic alkenes C8-C12 (only heptanoic acid


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was obtained from 1-octene in the presence of InCl3 8). Oxidation of higher aliphatic olefins using tert-butylhydroperoxide was not reported. Another well-known method is ozonolysis, which has been used on the industrial scale for the production of azelaic acid from oleochemicals 10.

Although ozonolysis is still being developed 11, the method suffers from the toxicity of O3 and

explosion risks. Currently, chemists are aware that the best choice for performing C=C bonds cleavage is molecular oxygen or hydrogen peroxide because they are readily available and environmentally friendly oxidants. Molecular oxygen is less expensive than H2O2 and thus seems to be better for large-scale production. However, O2 works well only with aromatic olefins that have a benzene ring in the vinyl position 12. In the case of aliphatic olefins, the reaction requires sophisticated and/or expensive catalysts to give good yields of the cleavage products for the reaction with molecular oxygen 13. The reactivity of aliphatic alkenes that have a terminal C=C bond is even lower. Hydrogen peroxide is perhaps the most common choice for the oxidative cleavage of aliphatic C=C bonds. It is used together with various catalysts that are based on selenium 14, palladium 15, rhenium 16, ruthenium 17, iron 18 and tungsten 19,22-33. Recently a lot of attention is also paid to zeolites and MOF materials as catalysts. For example metal-organic frameworks like MIL-101 were shown 20 to catalyse oxidative cleavage of terminal olefins to carboxylic acids efficiently (e.g. 85% yield of undecanoic acid was achieved). However, according to literature 21, zeolites like Ti-Beta, TS1 or NaY catalyse oxidation of olefins with H2O2 that yields mostly epoxides and only small amounts of carboxylic acids. Iron is a ubiquitous metal in our civilization, and it would be great to use its compounds as catalysts in the oxidative cleavage of olefins. However, a competitive reaction that leads to unproductive H2O2 decomposition (to H2O and O2) may be a serious problem on a large scale.


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Tungsten compounds are known to be very efficient and versatile catalysts, and they work well in the oxidation of almost all types of olefinic substrates. The oxidative cleavage of C=C double bonds by H2O2 begins with epoxidation catalysed by tungsten species. The epoxide undergoes hydrolysis and/or perhydrolysis, leading to the formation of a vicinal diol and/or hydroperoxyalcohol. Theses intermediates undergo C-C bond scission and are also catalysed by a tungsten species to form aldehydes. These aldehydes are further oxidized to give carboxylic acids. (Figure 1). Nevertheless, other intermediate products are possible (hydroxyketones and lactones) 19. The generally accepted mechanism for the oxidative cleavage of C=C double bonds involves activation of a W catalyst in a reaction with H2O2. This leads to the formation of O-O bridges in the structure of the catalyst (Figure 1), which then reacts with the double bonds of olefins 22.

[O]

R

R

OH

H2O

O

H2O 2

R

CH2

+

OH

OH

O

+

O

R

H2O 2 H2O 2 O

+

O OH

O

- H2C=O O

OH

R

3O

H2O 2

H

O

O W

O

O

O

OH

O

Active form of catalyst : O

H2O 2

OH

R

OH

R

R

OH

H2O 2

R

OH

O R

O

O

O

O W

O P

O O

O

R OH

O

W O

O O

O O

O

W O

O O

- H2C=O

O

Figure 1. Steps of C=C double bond oxidative cleavage by H2O2 catalysed by a tungsten species 19.

Much progress has been made since the discovery of tungsten catalysts. In particular, tris(cetylpyridinium) 12-tungstophosphate has been used as a catalyst for the C=C bond


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oxidative cleavage with 35% H2O2 in tert-butanol 23. The highest yields of carboxylic acids were achieved when cyclic olefins were used (up to 90%), and they were the lowest when 1-octene was used (45%). Later, Noyori and co-workers found that [CH3(n-C8H17)3N]HSO4 is an efficient acidic phase transfer catalyst (PTC) in the oxidative cleavage of cyclohexene to adipic acid (90% yield) with 30% H2O2 in the presence of Na2WO4 24. However, that acidic PTC is quite expensive. Venturello and co-workers 19 synthesized and used methyltrioctylammonium tetrakis(oxodiperoxotungsto)phosphate to catalyse the oxidation of C=C bonds with 40% H2O2 in the absence of an organic solvent. They achieved corresponding carboxylic acids with yields of approximately 80% from aromatic olefins (styrene), cyclic olefins (cyclohexene) and even linear terminal olefins (1-hexadecene). Another example is the use of the Q3{PO4[WO(O2)2]4} catalyst in the oxidation of cycloalkenes and unsaturated fatty acids to appropriate dicarboxylic acids (yields of 60-86%) (where Q = [n-Bu4N]+ or [C5H5N(n-C16H33)]+ or [Me(n-C8H17)3N]+). The Q3{PO4[WO(O2)2]4} catalyst can be obtained from H3PW12O40 or H2WO4 and H3PO4 and an appropriate quaternary ammonium halide (QX) in the reaction with H2O2 25. Additionally, other peroxotungstate complexes with organic ligands (e.g., pyridinium) have been used in the cleavage of functionalized cyclic olefins with 35% H2O2 to produce bis-acids in high yields 26. The readily available phosphotungstic acid (H3PW12O40) was used without a PTC to obtain adipic acid (95% yield) and other polycarboxylic acids from cyclic olefins 27 in the reaction with H2O2. Even simple H2WO4 works well because in the presence of H3PO4 it is converted in situ (during oxidation of olefin) to H3PW12O40 or to the peroxo-complex, {PO4(WO(O2)2)4}3-, in the presence of both H3PO4 and hydrogen peroxide. Therefore, adipic acid can be produced on a


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large scale from cyclohexene using a recyclable catalyst system consisting of H2WO4, H2SO4 and H3PO4 without the need for any PTC or solvent 28. Recently, an article that describes the use of a tungstate species supported on zinc-modified tin dioxide (W/Zn–SnO2) in the oxidative cleavage of C=C bonds with 30% H2O2 was published. The so-called “release and catch” catalyst works well in the case of cyclic and aromatic olefins but gave moderate yields of carboxylic acids in the case of aliphatic alkenes despite the use of a relatively large amount of W (10 mol%) 29. Much attention has been paid to oxidative cleavage of unsaturated fatty acids. For example, the double bond in oleic acid has been cleaved to azelaic acid (yield up to 91%) by the use of 60% H2O2 (amount up to 8 eq.) and H2WO4 30. The oxidative scission of oleic acid was quite efficiently performed (yields >80%) using an oxidant-catalyst system composed of 30% H2O2 and [C5H5N(n-C16H33)]3{PO4[WO(O2)2]4} (1/5/0.02 molar ratio) at 85°C within 5 h. Several other catalysts have also been prepared in situ from tungstophosphoric acid, H2O2 and different quaternary ammonium salts (Q+, Cl-) in the oxidation of oleic acid to azelaic acid 31. Recently, a similar investigation on the oxidation of 1-octene, 1-decene and 1-dodecene via 30% H2O2 in the presence of peroxotungsten compounds of the general formula of Q3{PO4[WO(O2)2]4} was reported 32. Many different quaternary ammonium and phosphonium salts have been tested as PTCs by Kadyrov and Hackenberger for the oxidation of aliphatic terminal olefins (C10, C12, C18) with H2O2 in the presence of Na2WO4 and H3PO4 to yield the corresponding carboxylic acids 33. A PTC or solvent is required because of the poor solubility of olefins in water.


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Herein, we present results on the oxidation of long-chain aliphatic terminal alkenes (C30+) to carboxylic acids with hydrogen peroxide in the presence of tungstic acid and a phase transfer catalyst without solvent or with a small amount of diluents. Oxidative cleavage of such long olefins has not yet been studied. The C30+ -olefin substrate can be obtained from ethylene in the oligomerization process, and the long chain carboxylic acid products can be used for the production of important chemicals, such as surface active agents, lubricants, greases, plasticizers, waxes, polymers, adhesives and household products (soaps, detergents, cosmetics) 1. The importance of the elimination of halide ions in quaternary ammonium salts (phase transfer catalysts) and the influence of H2SO4 and H3PO4 are discussed. Purification of the crude oxidized product and tungsten reuse are also presented. EXPERIMENTAL SECTION Materials The following compounds were used as received: 1-dodecene (93-95%, Acros Organics), Alpha Plus C30+ olefin (Chevron-Phillips According to Technical Data Sheet, it contains 71.4 wt% of n-α-olefins and 24.7 wt% of branched α-olefins), hydrogen peroxide (50 wt% in water, stabilized, Acros Organics; 30 wt% in water POCH), tert-butylbenzene (Acros Organics), methylcyclohexane – MCH (Alfa Aesar), heptane (Chempur), tungstic acid - H2WO4 (Fluka), cetylpyridinium chloride monohydrate - CPC (Aldrich), cetyltrimethylammonium ptoluenesulfonate - CTMAPTS (SIGMA), cetyldimethyl(2-hydroxyethyl)ammonium dihydrogen phosphate - Luviquat mono CP AT1 (Aldrich 30% in H2O), methyltrioctylammonium hydrogensulfate - MTOAHS (Sigma-Aldrich), tetrabutylammonium hydrogensulfate - TBAHS (Merck-Schuchardt).


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Melting points were determined on EZ-Melt Automated Melting Point Apparatus Digital Image Processing Technology, Stanford Research System. The amount of tungsten in oxidized C30+ product was determined using AAS or ICP-AES methods. The 1H NMR spectra were recorded on an Agilent 400-NMR working at 400 MHz. Samples were prepared in CCl4 or CDCl3. Oxidation of 1-dodecene with H2O2 1-dodecene (30 mmol; 6.7 ml; 5.05 g), a catalyst containing H2WO4 (3 mol%; 0.9 mmol; 0.22 g), cetylpyridinium chloride (3 mol%; 0.9 mmol; 0.32 g), phosphoric acid (0.5 ml; 0.5 M), hydrogen peroxide (50 wt.%; 120 mmol; 6.8 ml; 8.16 g) and diphenyl (0.42 g) as the internal GC standard were introduced to a 25-ml round bottom flask equipped with a magnetic stirrer and condenser. The reaction mixture was stirred (1400 rpm) at 70°C for 800 min. During the reaction, samples were taken, and their compositions were determined by GC. Oxidation of C30+ olefins C30+ α-olefin (40-60 g), a catalyst containing H2WO4 (1.2-7.2 mmol), PTC (2.0-7.2 mmol), 1 M H3PO4 (0-2 mmol) or 1 M H2SO4 (0-4 mmol) and (optional) a hydrocarbon diluent (32 g) were introduced to a 250-ml round bottom reactor equipped with a mechanical stirrer and a condenser. The mixture was heated to 75°C; then, hydrogen peroxide (5-8 equiv. 50 wt.% or 30 wt.%) was pumped into the reactor (ca. 0.5 g/min), and the mixture was heated to the desired temperature. The reaction was performed at 80-100°C for 10-16 h at 300-600 rpm. During oxidation, reaction samples of the crude product were taken and dried at 60°C, and their acid numbers (AN) were determined.


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When oxidation was finished, the crude products were washed with 500 ml of distilled water and dried at 60°C, and their acid numbers (AN) and saponification numbers (SN) were determined. Crude product purification by sedimentation, decantation and crystallization The purification of the chosen oxidation product (AN 64 mgKOH/g) from tungsten was performed via sedimentation followed by decantation and crystallization in a selected solvent. To a round-bottomed flask (250 ml), we introduced 15.0 g of dried oxidation product and 30-100 ml of the solvent. The flask was immersed in an oil bath at a temperature of 90°C. After melting and dissolving the oxidation product (approximately 15 min), the contents were mixed for a while and left at 90°C for sedimentation for 135 min. Then, we poured (decanted) the supernatant into a crystallizer and allowed it to crystallize overnight. The resulting crystals were filtered and dried at 20-40°C, and the tungsten content was determined. To purify the product by adsorption of tungsten compounds on Al2O3, the hot supernatant was directly poured on a heated (90°C) adsorption column (diameter of 15 mm and length of 160 mm) filled with active Al2O3 (particles < 0.1 mm; previously calcined at 600°C for 3 h). The purified solution was allowed to crystallize overnight. The resulting crystals were filtered and dried at 20-40°C, and the tungsten content was determined. Crude product purification by extraction To ca. 72 g of the oxidation products obtained in reactions No. 26 and 27 (Table 1), 25 g of H2O was added, and the mixture was extracted twice with methylcyclohexane (MCH) (2 x 70 or


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85 g of MCH). The MCH was evaporated from the organic phase. A white solid product was obtained, and the tungsten content was determined. Recovery and reuse of tungsten compounds According to the above-described procedure (sedimentation, decantation, and crystallization), the precipitate obtained by purification of the product of reaction No. 21 (Table 1) was combined with the aqueous filtrate from washing of the crude product. The solvents were evaporated, and the recovered catalyst was reused in reaction No. 22 (Table 1).

Oxidation of C30+ olefins in a reaction calorimeter Oxidation of C30+ olefins was conducted in a Mettler Toledo reaction calorimeter (RC1e) equipped with an RTCal heat flow sensor at a volume of 500 ml. First, the C30+ α-olefin (80 or 90 g), the catalyst containing H2WO4 (4.8 or 5.4 mmol), CTMAPTS (4.4 or 4.9 mmol), 1 M H3PO4 (1.4 or 1.5 mmol) and tert-butylbezene (64 or 36 g) as the diluent were introduced. The mixture was heated to 80°C; then, hydrogen peroxide (33 or 38 g, 50 wt.%) was pumped into the reactor (0.4 g/min). The reaction was conducted at 80°C for 6 h at 300 rpm. The temperature of the reaction mixture was automatically controlled. The heat of the process was measured. Calculation of bromine number and maximum acid number The double bond content of C30+ α-olefins was calculated using 1H NMR spectroscopy with naphthalene as an internal standard (Figure S1, Suppl.). The NMR tube was charged with a solution prepared by dissolving 0.50062 g of α-olefins and 0.05572 g of naphthalene in carbon


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tetrachloride. The ratio of double bonds count to number of naphthalene molecules was calculated by determination of the surface area of peaks corresponding to appropriate molecule fragments. The calculated double bond count per unit mass of α-olefins (0.002035 mol of C=C per 1 g of olefin) corresponds to theoretical bromine number 32.52 g Br2/100 g. Based on the content of double bonds the average molecular mas of C30+ olefins is calculated as 491 g/mol which is very close to molecular mas of C35H70. We assumed that all the C=C bonds are terminal (CH2=CH-R) and CH2 group is oxidized to formic acid which is removed during washing the product. Oxidation of C35H70 yields carboxylic acid C33H67COOH, so the calculated maximum theoretical value of AN was 110 mg KOH/g. Detailed description of above calculations is given in Supplementary Information. Esterification of oxidized product with MeOH 10 g of dry oxidized product, 25 ml of MeOH and 0.1 ml of conc. H2SO4 was placed in the stainless steel reactor. The esterification was conducted at 90°C during 20 h under the pressure of N2 (7 bar). Then the esterified product was washed with MeOH (3 x 20 ml) and dried. Gas chromatography analyses GC analyses were performed on a Hewlett-Packard 5890 Series II gas chromatograph with a flame ionization detector (FID) using a (ZB-5HT) capillary column (30 m ˣ 0.32 mm ˣ 0.10 μm film). Carrier gas: helium. The following conditions were used: column head pressure of 60 kPa, injection port temperature of 280°C, and an oven program of 80°C for 1 min that was then ramped to 280°C at 20°C/min with a final time of 2 min at 280°C. The detector temperature was 280°C. The qualitative analyses were performed using a GC (Agilent Technologies 7890C)


12

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connected with to an MS (Agilent Technologies 5975C) detector. The GC-MS was equipped with an HP 5MS column (30 m × 0.25 mm × 0.25 μm film, ionization with EI at 70 eV). Determination of H2O2 concentration A sample from the aqueous phase taken after the oxidation process was dissolved in pure acetic acid and iodometrically analysed (using 0.1 M solution of Na2S2O3 for titration). Acid number AN Samples (ca 0.3 g) taken from reactor were dried at 60°C and then introduced to a conical flask equipped with condenser. Then 25 ml of xylene with 2-methyl-2,4-pentanediol (2:1 v/v) was added. Mixture was heated up to get clear solution. Hot mixture was titrated with 0.05 M KOH in ethanol. Phenolphthalein was used as an indicator. Acid number (AN) is the amount of KOH (mg) required to neutralize carboxylic groups in 1 g of sample. Saponification number SN Samples (ca 1 g) of product were dried at 60°C and then introduced to a conical flask. Then 25 ml of xylene with 1-propanol (4:1 v/v) and 25 ml of 0.1 M KOH in ethanol was added. Mixture was heated under reflux for 30 minutes. Hot mixture was titrated with 0.1 M HCl. Phenolphthalein was used as an indicator. In blank test the same mixture without the sample from reaction was used. Saponification number (SN) is the amount of KOH (mg) required to neutralize free carboxylic groups and esters in 1 g of sample.


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RESULTS AND DISCUSSION A mixture of long-chain terminal olefins with more than 30 carbon atoms (C30+ α-olefins) was used as the starting material in this study (containing 71.4 wt.% of n-α-olefins and 24.7 wt.% of branched α-olefins). The double bond content of the C30+ α-olefins was calculated using 1H NMR spectroscopy with naphthalene as the internal standard (Figure S1, Suppl.), which gave the theoretical bromine number of 32.52 g Br2/100 g. The oxidation reactions of C30+ olefins with H2O2 (30-50 wt.% aq) that were catalysed by H2WO4 and PTC were conducted in the presence or absence of a mineral acid and a diluent (heptane, methylcyclohexane or tertbutylbenzene). Commercially available halogen-free quaternary ammonium compounds, including cetyltrimethylammonium p-toluenesulfonate (CTMAPTS), cetyldimethyl(2hydroxyethyl)ammonium dihydrogen phosphate (Luviquat), methyltrioctylammonium hydrogensulfate (MTOAHS), and tetrabutylammonium hydrogensulfate (TBAHS), were used as the PTCs. For comparison, cetylpyridinium chloride monohydrate (CPC) was used. The course of the oxidation was monitored by measuring the acid numbers (AN) and saponification numbers (SN), which represent the total amount of carboxylic acids and total amount of esters plus carboxylic acids, respectively. The effect of the amount of H2WO4, PTC, H2O2, H2SO4, and H3PO4, the mixing rate and temperature were studied. The acid numbers of the crude products and final products obtained after washing with water are presented in Table 1. The acid numbers of the washed products are discussed in this section. Based on the 1H NMR spectroscopy of oxidized products, it has been established that the conversion of C30+ olefins for these reactions is 100% (characteristic peaks for the protons in the vicinity of C=C bonds were not detected; Figure S6, Suppl.). The maximum theoretical value of AN is 110 mg KOH/g. It was calculated based on the amount of C=C bonds in the 1 g of


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substrate, which was determined using 1H NMR with naphthalene as internal standard. We assumed that all the C=C bonds are terminal (CH2=CH-R) and formic acid formed by cleavage of C=C bonds is removed during washing the product. In fact the substrate contains some internal olefins (RCH=CHR’) where R’ may be a methyl, ethyl, propyl or other alkyl substituents. These alkyl substituents with short hydrocarbon chains are converted to carboxylic acids soluble in water (eg. acetic, propionic) which are mostly removed during washing the products (proved by GC-MS analysis of water phase). Therefore, yield of long chain carboxylic acids based on AN or SN values can be only estimated, eg. AN=80 mg KOH/g corresponds to the yield ca. 72%. The dependence of maximum yield of carboxylic acids as a function of acid number (AN) or saponification number (SN) in the oxidative cleavage of C30+ olefins are given in Supplementary Information (Figure S5, Suppl.). Table 1. Oxidation of C30+ olefins with hydrogen peroxide a. No

H2WO4 PTC

PTC

H2SO4 H3PO4 H2O2

wt.% b

wt.% b mol/g b

temp. mixing ANcr ANw SNw ENw H2O2 left

equiv. b °C

rpm

mgKOH/g

wt.% c

1

1.5%

Luviquat CP 2.5%

0

17

5

90

500

49

39

63

24

5.4%

2

3.0%

Luviquat CP 2.5%

0

17

5

90

500

74

76

102

26

1.0%

3

1.5%

Luviquat CP 5.0%

0

17

5

90

500

26

13

22

9

12.8%

4

1.5%

Luviquat CP 5.0%

0

34

5

90

500

47

33

55

22

12.2%

5

1.5%

Luviquat CP 5.0%

17

0

5

90

500

67

59

75

16

2.5%

6d

1.5%

Luviquat CP 2.5%

0

17

8

90

450

63

50

71

21

13.1%

7

1.5%

CTMAPTS

2.5%

0

0

5

90

400

63

64

80

16

-k

8

1.5%

CTMAPTS

2.5%

0

0

5

90

600

49

48

63

15

-k

9

1.5%

CTMAPTS

2.5%

0

0

5

90

500

68

68

83

15

-k

10

1.5%

CTMAPTS

2.5%

0

17

5

90

500

74

76

88

12

1.2%

11

1.5%

CTMAPTS

2.5%

0

34

5

90

500

75

73

90

18

1.1%


15


Page 16 of 41

12

1.5%

CTMAPTS

2.5%

0

34

8

90

500

77

73

96

23

13.1%

13

1.5%

CTMAPTS

2.5%

34

0

5

90

500

62

62

82

19

0.8%

14

1.5%

CTMAPTS

2.5%

34

17

5

90

500

68

66

87

21

1.5%

15

1.5%

CTMAPTS

2.5%

68

17

5

90

500

62

59

85

26

1.3%

16d

1.5%

CTMAPTS

2.5%

34

17

8

90

500

70

63

95

32

11.3%

17

1.5%

CTMAPTS

2.5%

34

17

7

100

500

67

64

94

31

1.2%

18

1.5%

CTMAPTS

1.5%

0

17

5

90

500

70

67

86

19

2.2%

19

0.5%

CTMAPTS

2.5%

0

17

5

90

500

24

25

37

12

17.4%

20

1.5%

CTMAPTS

3.5%

0

17

5

90

500

78

76

87

10

1.2%

21

3.0%

CTMAPTS

2.5%

0

34

5

90

500

59

58

87

29

1.1%

22e

0%

CTMAPTS

2.5%

0

17

5

90

500

50

47

71

24

0.8%

23f

1.5%

CTMAPTS

2.5%

0

17

5

90

500

75

74

98

24

1.2%

24g

1.5%

CTMAPTS

5.0%

0

17

6

80

400

48

64

78

15

7.9%

25g

1.5%

CTMAPTS

5.0%

0

17

6

80

300

48

63

81

18

8.7%

26gj

3.0%

CTMAPTS

2.5%

0

17

6

80

300

70

65

81

17

1.7%

27dgj 3.0%

CTMAPTS

2.5%

0

17

8

80

300

76

62

79

17

0.8%

28h

1.5%

CTMAPTS

2.5%

0

17

6

80

300

54

58

75

17

5.7%

29i

1.5%

CTMAPTS

2.5%

0

17

6

80

300

63

60

75

15

9.7%

30

1.5%

MTOAHS

2.5%

0

17

5

90

500

65

63

87

24

Oxidative Cleavage of Long-Chain Terminal ... - ACS Publications

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