Solvents Theory and Practice - ACS Publications

6 The Photochemical Smog Reactivity of

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Organic Solvents ARTHUR LEVY Battelle, Columbus Laboratories, Columbus, Ohio 43201

The chemical solvent industry is greatly affected by current air-pollution regulations on local, state, and national levels. Current control laws are based in large part on Los Angeles' Rule 66 which ranks specific solvents and classes of solvents according to their potential smog-forming capability. A number of studies have been conducted over the past several years that are aimed at defining the relationship between organic solvents and photochemical-smog production. This paper reviews and analyzes some of the more recent of these. Solvents are ranked according to various photochemical smog parameters, taking into account many of the condi tions (differences in chambers, concentration, light intensity, etc.) under which the particular studies were conducted.

V I J T h e n one discusses organic solvents and air pollution, there is an W

almost Pavlovian response to Los Angeles' Rule 66. In some respects

it is unfortunate that this response has developed as rapidly as it has and to the extent that it has across the nation. W h e n the rule was promulgated, Lewis J. Fuller who was the air pollution control officer of Los Angeles County, cautioned those who attempted to apply this rule to the rest of the country. H e said that other communities should first learn the character and extent of their local problems and then try to resolve these problems, possibly taking advantage of some aspects of Rule 66. H e also pointed out that the transfer of Rule 66 to other areas might stretch the utility of the rule too far. In the mid-1960 s when Rule 66 was being promulgated, the problem of photochemical smog was technologically still in its infancy. W e are now much more aware of the complexities of the atmospheric chemistry that are associated with the reactions of hydrocarbons and nitrogen oxides in the presence of sunlight. As a result, although an extensive amount of 70 Tess; Solvents Theory and Practice Advances in Chemistry; American Chemical Society: Washington, DC, 1973.

6.

LEVY

71

Photochemical Smog Reactivity

work was conducted before the rule was promulgated, it has

become

increasingly evident that the definition of reactivity of species in the atmosphere is an extremely complex problem—one that is associated with so many parameters that it is difficult to extrapolate basic laboratorytype reactivity experiments. Experimental reactivity is a problem unto itself, being a function of chamber design, chamber operation, and parameters such as hydrocarbon-nitric oxide concentration, humidity, background gas impurity levels, Downloaded by UNIV OF MASSACHUSETTS AMHERST on May 24, 2018 | https://pubs.acs.org Publication Date: June 1, 1973 | doi: 10.1021/ba-1973-0124.ch006

and light intensity. F o r a detailed discussion of this area of smog reactivity and for more general reviews of photochemical smog reactivity, the reader is referred to Refs. J, 2, and 3. In this paper some of the studies which followed the Los Angeles A i r Pollution Control District (4)

stud-

ies are reviewed, principally to show some of the complexities that exist and some results that may modify and help other agencies to apply the reactivities of organic solvents to atmospheric conditions. CO ppm;Ox!dont, pphm

é

8

8

S

NO* NOfc ppm

δ

b

- 8 5 * F 49 percent RH 9:30

—0.08 ppm HCHO —0.29 ppm totol oldehyde — 0.09 ppm HCHO — 0.12 ppm HCHO

National Paint and Coatings Association

Figure 1.

Typical smog profile—mineral spirits (4.0 ppm) + NO (2.0 ppm) (5)

Tess; Solvents Theory and Practice Advances in Chemistry; American Chemical Society: Washington, DC, 1973.

72

SOLVENTS THEORY A N D PRACTICE

Rule 66 provides a simple reactivity scale. It requires an 85% reduc tion of solvents emissions from various industrial application if these solvents are photochemically reactive. Photochemically reactive solvents contain: (1) 5% or more olefinic hydrocarbons, alcohols, aldehydes, esters, ethers, or ketones, (2) 8% or more of C 8 or higher aromatics, except ethylbenzene, (3) 20% ethylbenzene, toluene, branched ketones, or trichloroethylDownloaded by UNIV OF MASSACHUSETTS AMHERST on May 24, 2018 | https://pubs.acs.org Publication Date: June 1, 1973 | doi: 10.1021/ba-1973-0124.ch006

ene, or (4) A total of more than 20% of the above. W h e n the Los Angeles studies were being conducted, the two prin cipal criteria for defining photochemical reactivity were eye irritation and oxidant formation. B y definition a photochemically reactive condi tion or photochemical smog condition existed if the average oxidant in Los Angeles were 0.1 p p m for 1 hour. Since then the National A i r Quality Standards have reduced that level to 0.08 p p m ozone for 1 hour. T h e early Los Angeles work d i d attempt to establish general regions of reac tivity for some solvents.

However, since the Los Angeles group was a

pioneer in this field, it recognized that there were unresolved technical problems in establishing reactivity data.

Background air used in the

Los Angeles studies for example was not clean and was difficult to clean. As a result, the background levels of eye irritation and of oxidant forma tion were high, and interpretations from these studies were complicated. In the present paper two major studies are reviewed. One study was conducted b y Battelle-Columbus under the sponsorship of the National Paint, Varnish and Lacquer Association (5) (now the National Paint and Coatings Association), and the other was conducted at Stanford Research Institute under the auspices of the Environmental Protection Agency ( β ) . F o r both studies, new smog chambers were constructed (7,8)

which took

advantage of the earlier experiences of the Los Angeles Laboratories

(9),

the Public Health Service chamber (JO), and other chambers in the country

(II).

In most chamber studies 1-10 p p m of organic are allowed to react with 0.1-3.0 ppm nitric oxide. In this way a profile of the species being consumed or produced i n the atmosphere can be developed, and various reactivities can be determined. Figure 1 presents a typical profile from this method. In this figure, 4 p p m of a mineral spirit containing 15% aromatics reacted with 2 p p m nitric oxide.

NO2 was produced as the

hydrocarbon and nitric oxide was being consumed, and about the time that the N O was totally consumed, the ozone or oxidant began to appear. T w o important items are the N 0 2 maximum and the initial appearance of oxidant. Ozone makes up 80-90% of the total oxidant, and the two terms are often used interchangeably. A l l N O in the system is not ac-



6.

LEVY

73


• Trons-2-Butene ο Mesityl Oxide ο Mesitylene KM m-Xylene K H Ethylene K H Mineral Spirits (53.1 % or.) 40 KH 50% n-Octone/50% m-Xylene lot a-Methylstyrene KH Methyl tert-Butyl Ketone KH p-Cymene lot Tetrohydrofuron I ο I Oiisobutyl Ketone »—o—H Ethylbenzene KH 80% n-0ctane/20% m-Xylene h-o—I Methyl Isobutyl Ketone K H Toluene 30 I ο I tert-Butylbenzene h—ο—I Oiocetone Alcohol H H Minerol Spirits (15.0% or.) lot Styrene 0 2-Ethoxyethonol 25h K H Mineral Spirits (19.8% or.) KH Isophorone a Mineral Spirits (14.6% or.) Η—ο 1 92 %n-0ctane/8% m-Xylene Mineral Spirits (16.0 % or.) 20h ο Oi-n-Propyl Ketone ο Methyl Ethyl Ketone K H Cumene Κ—ο 1 Methyl η-Butyl Ketone Cyclohexone I5h Minerol Spirits (7.5% ar.) ο 1 N-Methyl Pyrrolidone KH Triethylomine — ο I Oiethylamine I0h — ο 1 Methyl η-Propyl Ketone I—ο—I Cyclohexanone I—ο I n-Octone H Isopropyl Alcohol KH Isobutyl Acetate KH Phenyl Acetate 5h I ο ι Acetone 104 Benzene h-oH Methyl Benzoate , I r-o ,1 2-Nitropropane •

100

•

1

» *

'

•

1

1

200 300 N0 t-Mox «minutes

1

'

1

1

400

t


Figure 2. counted for as N 0

2

during the reaction.

Ranking Based on NQ2 t-max (5)

because numerous nitrates are also being produced T h e initial appearance of oxidant, coincident with

the maximum N 0 2 , results from an important reaction in the smog process: NO

+

03

=

N02 +

02

Because of this rapid and efficient reaction, ozone does not build up to any significant level until most of the N O is consumed.


74

SOLVENTS THEORY AND PRACTICE 451-

401-


35

30

25

20

15

10

HCH Tetrohydrofuron K H Diisobutyl Ketone — ο — I Isophorone α Ν-Methyl Pyrrolidone I ο ι 2-Ethoxyethonol ι ο I Trans-2-Butene — ο — I Mesityt Oxide HOH Mesitylene h-cH a-Methylstyrene I ο I Methyl tert-Butyl Ketone -I Mineral Spirits (53.1 % or.) a 50 % n-Octone/50 % m-Xylene h o n Diocetone Alcohol ο 1 Ethylene a 80% n-Octone/20% m-Xylene I ο I Mineral Spirits (19.8 % or.) ο 92 % n-Octone/8 % m-Xyiene ο Mineral Spirits (14.6 % or ) Η Mineral Spirits (16.0% or.) - ο — — I p-Cymene Mineral Spirits (15.0 % or.) Methyl Isobutyl Ketone m-Xylene Mineral Spirits (75% or.) Toluene KH Ethylbenzene h-o—I Cumene I—ο 1 Methyl η-Butyl Ketone ο Styrene Hon Di-n-Propyl Ketone 1 ο I Methyl Ethyl Ketone I ο I tert-Butylbenzene Cyclohexane Methyl η-Propyl Ketone n-Octone ο Cyclohexonone lot Isopropyl Alcohol ο Diefhylamine lot Isobutyl Acetate Κ* 2-Nitropropane d Triethylomine ο Phenyl Acetate ο Methyl Benzoate ο Benzene Q Acetone

IX)

0.75 050 0.25 Oxidant Maximum ppm

0

t


Figure 3.

Ranking based on oxidant production (5)

A t the top of Figure 1, various points in the reaction are noted where samples were removed for specific analysis—i.e., for formaldehyde and total aldehyde. A t the end of the reaction, one observes the eye-irritation response. T w o panels of seven people each were used, and the average of each panel is shown at the top near the 6-hour reaction period. T h e C O profile in Figure 1 is a measure of dilution in the chamber mix and is not a measure of reaction. C O can be considered nonreactive in these systems and can be used as a tracer gas to follow the replenish-


6.

LEVY

75


ment of chamber air with clean air i n batch-type chamber reactions.

( Evi

dence that C O does participate i n the reaction has been observed b y several investigators CO

(12, 13, 14), but that does not preclude the use of

i n the above role. ) Using this type of reaction profile, various methods have been used

to define reactivity. In this paper, the discussion is limited to the rate of photooxidation of nitric oxide (expressed as the N 0

2

ί - m a x , the time to


reach maximum N 0 2 ) , the maximum oxidant produced or the dosage of

i

45J-K* Styrene KH α-Methylstyrene H-O-H Clean Air KH Tetrohydrofuran HOH Mesityl Oxide I ο I Trons-2-Butene Mesitylene 40 KH Toluene hoH m-Xylene — ο — I Ethylene hoH Minerol Spirits (53.1 %or.) Ethylbenzene 35 Cumene 50% n-0ctane/50% m-Xylene p-Cymene Isophorone Mineral Spirits (19.8% or.) 30 80% n-0ctane/20% m-Xylene Di-n-Propyl Ketone Mineral Spirits (16.0% or.) Minerol Spirits (14.6% or.) I ο I tert-Butylbenzene I ο I Methyl Isobutyl Ketone I ο I Diacetone Alcohol I—ο—\ Oiisobutyl Ketone I ο 1 Methyl n-Butyl Ketone « ο 1 N-Methyl Pyrrolidone 20 I—o—l 2-Ethoxyethanol I ο 1 Mineral Spirits (15.0 % or.) I o — l 92 % n-Octone/ 8 % m-Xylene I — ο — I Mineral Spirits (7.5% or.) I ο 1 Methyl Benzoate 15 I o — l Isobutyl Acetote Triethylomine H Oiethylamine Methyl tert-Butyl Ketone n-Octane 10 Phenyl Acetate Benzene Methyl n-Propyl Ketone —I Methyl Ethyl Ketone Acetone Cyctohexonone 2-Nitropropane Isopropyl Alcohol HCH Cyctohexone • > » ' 100 200 300 400 1

1

Arithmetic Mean, seconds National Paint and Coatings Association

Figure 4.

Ranking based on eye-response data

(5)


76

SOLVENTS

THEORY AND PRACTICE

oxidant (the ppm-time area under the oxidant curve), eye-response time, and formaldehyde formation. Battelle Solvent In

Study

the program

conducted for

the

National Paint, Varnish

and

Lacquer Association, 45 solvents were examined under the following con ditions: 4 p p m organic, 2 p p m nitric oxide.

Profiles were obtained for


the solvents, and reactivity measurements were obtained from the profiles.

40l-

3011

20 f-

151-

5l-

III ι ZO

ι ι ι I 13

Ethylene -ο—I a-Methylstyrene K H Mesityl Oxide Β Styrene I ο I Trons-2-Butene I ο I Mesitylene h-o-4 Methyl Isobutyl Ketone 2-Ethaxyethonol m-Xylene lot Methyl tert-Butyl Ketone K H Oiocetone Alcohol II Tnethytomine a Methyl n-Piopyl Ketone KH Isophofone KH Methyl η-Butyl Ketone h-oH Diisobutyl Ketone KH 50% n-Octone/50 % m-Xylene a Mineral Spirits (53.1% or.) KOH p-Cymene d Cumene KM Methyl Ethyl Ketone I ο I tert-Butylbenzene « Di-n-Propyl Ketone II Oiethytomine a 80 % nOctone/20 % m-Xylene a Toluene KH 92 % n-0ctane/8% m-Xylene II Mineiol Spirits (14.6% or.) KH Ethylbenzene ο Mineral Spirits (19.8% or.) H Mineral Spirits (160% or.) Id Mineral Spirits (15.0% or) a Mineral Spirits (7.5% oc) a N-Methyl PyrroWone ο Isopropyl Alcohol ο Cyclohexonone loi Cyctohexone ο letrahydiofuran lot n-Octone ο Acetone lot 2-Nitropropone lot Isobutyl Acetate ο Methyl Benzoote ο phenyl Acetote ο Benzene ι ι ι ι I ι ι ι ιJ ι ι ι ι I IJO 05 0 Formoldehyde, ppm National Paint and Coatings Association

Figure 5.

Ranking based on formaldehyde production

(5)


6.

LEVY

Table I.


77


Category Summary (5)

Solvents

N02 t-Max

Oxi dant Max

Acetone Benzene Jrans-2-Butene ferJ-Butylbenzene Cumene Cyclohexane Cyclohexanone p-Cymene Diacetone alcohol Diethylamine Diisobutyl ketone Di-n-propyl ketone 2-Ethoxyenthanol Ethylbenzene Ethylene Isobutyl acetate Isophorone Isopropyl alcohol Mesitylene Mesityl oxide Methyl benzoate Methyl tert-butyl ketone Methyl isobutyl ketone M e t h y l η - b u t y l ketone Methyl ethyl ketone Methyl η - p r o p y l ketone iV-Methyl pyrrolidone a-Methylstyrene Mineral spirits 7.5% ar. 14.6% ar. 15.0% ar. 16.0% ar. 19.8% ar. 53.1% ar. 2-Nitropropane n-Octane 92% n-Octane/8% m-Xylene 80% n-Octane/20% m-Xylene 50% n-Octane/50% m-Xylene Phenyl acetate Styrene Tetrahydrofuran Toluene Triethylamine m-Xylene

1 1 3 2 2 2 1 3 2 1 2 2 2 2 3 1 2 1 3 3 1 3 2 2 2 1 2 3 2 2 2 2 2 3 1 1 2 2 3 1 2 2 2 1 3

1 1 3 1 2 1 1 2 3 1 3 2 3 2 3 1 3 1 3 3 1 3 2 2 1 1 3 3 2 2 2 2 3 3 1 1 2 3 3 1 2 3 2 1 2

Formal Eye de Re sponse hyde 1 1

1 1

1

1 1 1 1 1 1 1 1 1 1 1

1 1 1 1 1 1 1 1

1 1 1

1 1 1

1 1 1 1 1 1 1

1 1

1 1 1 1 1

1 1 1 1 1 1 1 1 1 1 1 1

1 1 1 1 2 1 3 2 2 1 2

1 1 1 1

1 1 1 1


Aver aged Rating 1 1 2.5 1.2 1.7 1.2 1 1.7 1.7 1 1.7 1.5 1.7 1.7 2.7 1 1.7 1 2.5 2.5 1 2 1.7 1.5 1.2 1.0 1.7 3 1.5 1.5 1.5 1.5 1.7 2.2 1 1 1.5 1.7 2.2 1 2.2 2 1.7 1 2

78

SOLVENTS THEORY AND PRACTICE

T h e four reactivities discussed here are N 0 2 f-max, maximum oxidant, eye response, and formaldehyde production. Figure 2 shows the 45 solvents ranked with respect to N 0 2 f-max. T h e solvents are ranked from highest reactivity to the lowest.

Two

olefinic materials are the most reactive (Figure 2) followed by two aromatics, mesitylene and m-xylene.

Further down the list as reactivity

decreases oxygenated materials appear at the lower end of the reactivity scale, and the ketones and esters show up as the least reactive i n terms Downloaded by UNIV OF MASSACHUSETTS AMHERST on May 24, 2018 | https://pubs.acs.org Publication Date: June 1, 1973 | doi: 10.1021/ba-1973-0124.ch006

of N 0 2 f-max. Figure 3 ranks the solvents according to maximum oxidant formation. Tetrahydrofuran and diisobutyl ketone are the most reactive, trans-2Butene and mesityl oxide, which rank highest in N 0 2 f-max, are in posi tions 40 and 39, respectively in this oxidant scale. T h e ketones, esters, and alcohols rank lowest in oxidant production. Figure 4 ranks eye-response as the arithmetic mean response time. Styrene and α - m e t h y l s t y r e n e are the most reactive species partly because of their benzyl groups.

Heuss and Glasson (15)

showed that peroxy-

benzoylnitrate ( P B z N ) , a specific lachrymator produced in these systems, is 200 times more reactive than peroxyacylnitrate, which itself is a fairly potent lachrymator. Tetrahydrofuran, mesityl oxide, and *rans-2-butene are high in eye irritation (Figure 4). Clean air is also ranked in Figure 4 at an average eye response of 300 sec. Six solvents are as irritating or less irritating than clean air. E y e response is very subjective, and in my opinion response times over 200 sec indicate a low irritation factor.

Because of this subjectivity, these six

solvents might be considered non-eye-irritating solvents. Figure 5 shows ratings based on formaldehyde production. Romanovsky et al

(16) noted a significant correlation between eye-response time

and formaldehyde production. A comparison of Figure 5 with Figure 4 suggests that the scatter in eye irritation response indicates a weakening relationship between eye irritation and formaldehyde concentration. Tetrahydrofuran, toluene, and ethylbenzene exhibit high eye irritation and low formaldehyde concentraTable II. Reactivity Category 3 high reactivity 2 intermediate reactivity 1 Low reactivity β

Category Ranges

NO2 t-Max, min

Oxidant Max, ppm

Ε. I. sec*

Formaldehyde, ppm

0-100 101-200 201-360

0.57-0.85 0.29-0.56 0-0.28

0-60 61-160 161-360

1.0-1.6 0.5-1.0 0-0.5

Eye response.


LEVY


-j diacetone alcohol diethyl cellosolve -Q

j sec. butyl acetate


isobutyl acetate -\ isobutyl alcohol \θ\

isopropyl alcohol

J—O—J η - b u t y l alcohol Θ cellosolve acetate I

Ο \θ\

I methyl isoamyl ketone toluene

f — O H methyl isobutyl ketone )—0—\

10

9

n-nonane

j — Ο — \ methyl ethyl ketone

8

I

Q

j

1,1,2-trichloroethane

7

|—Ο—I 2-nitropropane

6

[ — Ο — I η - b u t y l acetate

&

—

4

J - O - J ethyl acetate |—O—J methylene chloride

3

H H

2 —

|-0-j cyclohexanone

Freon113

PURE AIR

-L 0.10

0.20

0.30

0.40

M A X I M U M O X I D A N T - ppm (normalized to 0.10 ppm N 0 maximum) 2

Environmental Science Technology

Figure 6.

Rankings based on normalized maximum oxidant (6)


80

SOLVENTS

THEORY AND PRACTICE

tion. Although toluene and ethylbenzene contain benzyl structures, other lachrymators such as P A N and P B z N also contribute to eye irritation (15). Category Summary. Ranking individual solvents by parameter cate gories as in Figures 2-5 is not very practical. Table I evaluates reactivities of the solvents on a scale of 1-3; high, intermediate, or low reactivity (as defined by Table II).

This provides a rather broad classification.

In Table I only a few solvents exhibit the same ranking on all four scales. Low-category solvents however are fairly consistent in their rank Downloaded by UNIV OF MASSACHUSETTS AMHERST on May 24, 2018 | https://pubs.acs.org Publication Date: June 1, 1973 | doi: 10.1021/ba-1973-0124.ch006

ings.

Acetone, benzene, cyclohexanone, diethylamine, isobutyl acetate, Ranking — no background mix

j

21

j (71% 0 3 ) diethyl cellosolve

ρ

114

|Gf (86% 0 3 ) celtosolve K u t i t i

20 19

|-OH

(M% 0 3 ) n-nooant

Θ

183% 0 3 ) isobutyl acetate

18 I

17

Ο HH

16

10 18

I (91% 0 3 ) sec. butyl acetata

\θ\ (88% 0 3 ) isobutyl alcohol

14

\θ\ (87% O ^ n - b u t y l acetate

17 6 15

Θ (94% 0 3 ) η-butyl alcohol

13 12

HH

11

HH

yo\

9

11

\ (91% Ο3) methyl isobutyl ketone

13

(92% 0 3 ) mathyl isoamyl katona

|—©H

(89% 05) 1.1.2-trichloroathana

7

|—©H

(89%0 )Fraon113

6

\θ\ (91% Ο3) mathyl ethyl katona h-©H

7

(91% Ο3) 2-fiitropropene

8

5

21

(92% 0 3 ) diacatona alcohol

0

j

1°

19 16

(86% 0 3 ) isopropyl alcohol

IS

20

8 3

3

9 2

(91% Oj) cyclohexanone

5

Θ (91% 0 3 ) ethyl acetata

4

HH

(87% O3) BACKGROUND MIX

4

Θ (94% 0 3 ) methylene chloride U-

12

Θ (98% OJJ) toluene

J 0.2

0.3

I 0.4

ι

0Λ

1

0.6

0.7

0Λ

OXIDANT MAXIMA - ppm

Environmental Science Technology

Figure 7.

Rankings based on oxidant maxima in runs with background mix plus 8 ppm test solvent (6)



methyl benzoate, 2-nitropropane, η - o c t a n e , phenyl acetate, and triethylamine exhibited low reactivity in all categories. a-Methylstyrene exhibited high reactivity in all categories.

In most cases the specific reactivity de

pended on the type of reactivity response being examined. This illustrates the complexity of attempting to define solvent reactivity for any specific application. T h e chemical reactivity of benzene was low in these four categories examined, but in another recent study benzene was a significant contributor to atmospheric aerosol (17).


SOLVENTS THEORY

1.00 ppm Initial Nitrogen Dioxide

τ

(78% 0 ) diethyl cellosolve 3

I

Ο — |

(81% 0 ) cellosolve acetate 3

8


AND PRACTICE

O - H (90% O3Î sec. butyl acetate

7

f — O - J (89% 0 ) isobutyl acetate

6

H>{ (90% 0 ) isobutyl alcohol

3

3

13 (88% O3) η-butyl alcohol 4|

13 (92% O3) isopropyl alcohol 1

3

H H

2|

(88% 0 ) BACKGROUND MIX 3

|Ξ| (88% 0 ) cyclohexanone 3

Θ (91% Oo) toluene

1

J

1

0.2

0.4

0.3

0.5

0.6

0.50 ppm Initial Nitrogen Dioxide

I

Η (79% 0 ) diethyl cellosolve 3

Θ (84% 0 ) cellosolve acetate 3

HH

8 M

7| Η

(91% O3) isobutyl acetate

(91% Ο3) sec. butyl acetate (91% 0 ) isobutyl alcohol 3

6 KH

(96% 0 ) isopropyl alcohol 3

5! Θ (89% 0 ) η-butyl alcohol 3

4 Ο (91% O3) cyclohexanone 3 |-θ| (98% 0 ) BACKGROUND MIX

21

3

if— Ο (100%0 ) toluene 3

0.2

0.3

0.4

0.5

0.6

OXIDANT MAXIMA - ppm Environmental Science Technology

Figure 9.

Rankings based on oxidant maxima in runs with background mixes plus 4 ppm test solvent (6)


6.

LEVY

83


Ο eel losolve acetate diethyl cellosolve -Ο——I

sec. butyl acetate


Θ isobutyl acetate Θ η—nonane )S| 2—nitropropane Θ isopropyl alcohol \θ\ n—butyl acetate HH isobutyl alcohol Θ η—butyl alcohol \θ\ diacetone alcohol Θ methyl ethyl ketone |-ô-| methyl isobutyl ketone Θ methyl isoamyl ketone Θ

1,1,2-trichloroethane

ft Freon113 |-©H ethyl acetate |Ξ| methylene chloride \θ-\ BACKGROUND MIX |Ξ| cyclohexanone Θ toluene _J 1.0

_L 2.0

3.0

±

4.0

5.0

OXIDANT DOSAGES AFTER 7 HOURS - ppm · hr Environmental Science Technology

Figure 10.

Rankings based on oxidant dosages in runs with background mix plus 8 ppm test solvent (6)


84

SOLVENTS THEORY

Stanford

AND PRACTICE

Research Institute Studies

The solvent program at SRI was carried out in ways similar to the Baftelle-Columbus study.

In the Stanford studies the solvents were ex

amined with a clean-air background and with a hydrocarbon-mixture air

Table III.

Comparison of Oxidant—Maximum Rankings, ppm BCL

SRI


s

MIBK MEK Cyclohexanone Diacetone alcohol Isopropyl alcohol Isobutyl acetate Diethyl Cellosolve Toluene 2 Nitropropane β b e

0.45 0.28 0.10 0.60 0.09 0.08 0.68 0.44 0.07

3 5 6 2 7 8 1 4 9

0.13 0.13 0.085 0.24 0.12 0.15 0.22 0.08 0.10

6 5 7 3,4 3,4 2 1

— —

— —

Oxidant Dosage Rankings, ppm-sain S R I

BCL"

MIBK MEK Cyclohexanone Diacetone alcohol Isopropyl alcohol Isobutyl acetate Diethyl Cellosolve Toluene 2-Nitropropane b

0.34 0.35 0.31 0.40 0.40 0.44 0.55

4 5 8 1 6 3 2 9 7

4 ppm solvent/2 pp, NO. 1 ppm solvent/0.1 ppm NO*. 8 or 4 ppm solvent/1 ppm NO*, plus Background mixture.

Table IV.

a

SRI'

n

267 232 262 193 215 252 274 141 180

2 5 2 7 6 4 1 9 8

36 21 21 62 33 45 75 30 21

b

3 7,8,9 7,8,9 2 5 4 1 6 7,8,9

4 ppm solvent/2 ppm NO, 6 hr dosage. 1 ppm solvent/0.1 ppm NO*, 7 hr dosage.

background. T h e conditions were 1 p p m solvent and 0.1 ppm nitric oxide. Ranking data for 20 solvents are given in Figure 6, from a No. 21 (high reactivity) to pure air. Diacetone alcohol is highest in reactivity; cyclo hexanone is the lowest next to pure air. For solvents studied with a hydrocarbon background mixture, two mixtures were used: propylene (0.5 p p m ) , n-butane (2 p p m ) , toluene (1 ppm) and N 0 2 (1 or 0.5 p p m ) .

Eight ppm of solvent were used in

each experiment. Figure 7 tabulates the results. Also shown on this figure (on the right-hand side) is the relative ranking position that the solvent had when it was examined in a clean-air background (see Figure 6).


A


Figure 11.

Manufacturing Chemists Association

Concentration changes during photooxidation of trichhroethylene (0.8 ppm) with nitrogen oxides (0.1 ppm) (19, 20)

HOURS OF IRRADIATION


86

SOLVENTS THEORY A N D PRACTICE

change of two or three positions is not significant. A change of five or six positions is. In Figure 7, eight materials were shifted markedly in going from a clean-air background to a specific background mixture (Cellosolve acetate, n-nonane, isobutyl alcohol, η - b u t y l acetate, diacetone alcohol, Freon 113, cyclohexanone, and toluene). T h e first three solvents moved up in ranking, while the other five moved down. O f special interest is n-nonane. Although it was No. 10 solvent in Figure 6, it is No. 19 in Fig ure 7, fairly high in reactivity. This shift in reactivity with a background Downloaded by UNIV OF MASSACHUSETTS AMHERST on May 24, 2018 | https://pubs.acs.org Publication Date: June 1, 1973 | doi: 10.1021/ba-1973-0124.ch006

mixture that contains an aromatic and an olefin is borne out by the studies at Battelle-Columbus.

There seems to be a synergistic effect when a

paraffinic material reacts in the presence of an aromatic. Figure 8 is a plot of oxidant formation when a mixture of n-octane and m-xylene react in smog.

As the aromatic content of the system

increases, the oxidant reaches a maximum near 30%

aromatic.

This

synergistic effect is also supported by SRIs studies with n-nonane using a background mixture. Figure 8 also shows that esters tend to produce more oxidant while ketones produce less oxidant when either solvent reacts in the presence of background mixture.

While the addition of

toluene to the background mixture resulted in decreased reactivity (mea sured by oxidant max and oxidant dosage) there was a large increase in aerosol formation (as indicated by light scattering

measurements).

Effect of Initial Nitrogen Dioxide T h e quantity of nitrogen dioxide in the reaction will influence the overall reaction of any material in the atmosphere (18).

As part of the

SRI program, 10 solvents that were studied in the presence of a back ground mix were also examined with different levels of nitrogen dioxide (Figure 9); 4 p p m of solvent were added to background mixes containing

Table V .

Eye-Irritation Rankings" SRI*

BCLb MIBK MEK Cyclohexanone Diacetone alcohol Isopropyl alcohol Isobutyl acetate Diethyl Cellosolve Toluene 2-Nitropropane Air

213 295 309 214 318 258 239 106 309 280

2 6 7,8 3 9 5 4 1 7,8

162 2 201 5 193 4 188 3

Solvents Theory and Practice - ACS Publications

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