Chapter 12

Industrial Uses of Sulfur and Its Compounds

Figure 1.2 shows the correlation between GNP and sulfur use. The
present sulfur use is almost 100 lbs per capita per year in the U.S. The
sulfur consumption world-wide is related t o industrial production.
Figures 1.1 and 12.1 show some of the end products for the production of
which sulfur is an intermediate. Table 12.1 indicates how much sulfur
and sulfuric acid are used to prepare 30 important materials. Several
handbooks contain excellent reviews on the use of sulfur. The following
constitutes only a short summary of this field, because several end uses
are discussed in other chapters. Table 12.2 gives the weighted average for
the expected U.S. end uses for the year 2000. As is seen, the estimated
values do not differ significantly from the present, except for the field of
new uses, discussed in Chapter 14.

A. ELEMENTAL SULFUR

The estimated total world production of sulfur during 1976 was

about 80 million tons. About 60 million tons of this go into 120 m tons
of sulfuric acid. Table 1.3 and Chapter 7 list the volume and price of
earlier production. As mentioned above, because of its physical and
chemical behavior, elemental sulfur is the preferred form for selling and
shipping sulfur.
Since the middle 1950's, most Frasch sulfur from the Gulf of Mexico
has been shipped in liquid form and stored in liquid form at the terminal
for further distribution in heated tank cars. The safety problems caused
by the slow conversion of trace impurities to hydrogen sulfide have been
solved by purging and venting. Safety standards have been developed by
the National Fire Protection Association and other organizations. With
the advent of Claus sour gas sulfur, the shipment of solid sulfur has become
more popular. Essentially all Canadian sulfur is shipped in solid form.
279
280 SULFUR, ENERGY, AND ENVIRONMENT

Table 12.1
ELEMENTAL SULFUR EQUIVALENT REQUIRED IN MANUFACTURE
OF ONE TON OF PRODUCT (METRIC TON)

Sulfur Equivalent
Product equivalent 0ÌH2SO4
Fertilizers
Diammonium phosphate (DAP) 0.39 1.35
Granular triple superphosphate (GTSP) 0.28 0.95
P2O5 in 54% P2O5 w e t phosphoric acid 0.85 2.88
Wet phosphoric acid (54% P2O5) 0.45 1.56
Granulated ammonium polyphosphate (GAPP) 0.49 1.65
Normal superphosphate (NSP) 0.11 0.37
Liquid fertilizer 11-37-0 grade 0.59 1.98
Sulfuric acid, 100% 0.31 1.00
Synthetic fibre intermediates
Hydrogen cyanide (Modacrylic fibre) 0.07 0.25
Caprolactam (nylon 6 fibre) 0.92 3.12
Acetate rayon (fibres, photographic film, etc.) 0.03 0.10
Vulcanized synthetic rubber (SBR) 0.01 0.04
Carbon disulfide (fibres, cellophane, other
chemicals 0.85 2.86
Paper pulp 0.10 0.33
Indigo dye 0.28 0.91
Phenol by sulfonation (plastics) 0.40 1.35
Explosives (nitrocellulose) 0.15 0.52
Lithopone paint pigment 0.10 0.32
Leather tanning (chrome tan) 0.07 0.23
Teflan (100%) (herbicide) 0.38 1.28
Alum, 17% AI2O3 (water treatment chemical) 0.13 0.46
Sodium dichromate (tanning, dyeing, paint
pigments, etc.) 0.12 0.43
Uranium 2 3 5 16.4 55.34
Sodium sulfate (100%) 0.21 0.69
A m m o n i u m sulfate (100%) 0.22 0.74
After R.N. Shreve, 'Chemical Process Industries,' McGraw-Hill, New York, 1967.

Much research is presently under way to determine the best size and shape
of prills, slates, granules, and the like, and exploratory research is in
progress for converting sulfur to a form suitable for transport in pipelines
Berquin (1976). In the shipment of solid sulfur, moisture constitutes a
problem. Not only does it add to shipping weight, but it enhances corro-
sion of shipping vessels, because nascent rust can react with elemental
sulfur yielding pyrophoric iron sulfides, Section 3D.
Fig. 12.1 shows that acid is still the predominant intermediate.
However, the uses of elemental sulfur as a nutrient and fungicide in
agriculture is presently increasing. It will gain further importance in the
 INTERMEDIATES 281

Most sulfur is made into sulfuric acid The balance is Superphosphates

used in its dementai form or · η ««nous chemical Ammonium Phosphates
compounds. While sulfur is essential in almost Ammonium Sulfate
every segment of the economy, it is generally Mixed F e r t i l i z e r s
used as a processing aoerrt and seldom appears
in the final p r o d u c t

Containers a n d B o x e s Explosives
Nonferrous Metals
Newsprint
Magazines and Printing Papers Synthetic Rubber
P u c for Rayon and „ Storage B a t t e r i e s
Writing and Pine Papers
Wrapping and Bag Papers Textile Finishing
Film ^ - "
Sanitary and Tissue Papers
A b s o r b e n t Papers _ " "
^Aviation ^
^ " Rayon /Chemical .
^ Gasoline ^ >.
^. - " Cellophane ' Warfare , ^ v. lubricants^
^ " Carbon Tetrachloride 'Specialty,
Steels /synthetic Detergents PetroteumCatalysb vPa.ntsand\ \TiraCwd· v
Rubber Processing , ' " * « * ο * · * 'Megresium J Additives
Feed Aluminum Reduction \ Enamels \ vscoseTeN
*tiles ™
^cSted7abrfcs
N
Chemicals , ' rungxxles y„ Oyestuffs Anti-knockGacoline Paper Sizing a b>Αρρΐ-ηοβ
F s
60 r , c xAœtate Textiles

/
. - 'Rubber , Bleaching
Vulcanizing .-soybean Extraction
Synthetic Resins Water Treatment Pf Pr a . Μ« , η * ^ ^tended
\ τNTinardOthef^ Fabrics
Blended Fabri
Protective Coatings Pharmaceuticals \ ^ \Cbntainers
v Cellophane
NN
/ ''Soil S u l f u r „ leather Processing Dyeskiffs Insecticides \ Printing Inks
Galvanized .Photographic
^ " ' Phonography 0·! Well Acidizing Antifreeze ^Products s Film
y

Fig. 1 2 . 1 . End uses of sulfur (after Gittinger, 1 9 7 5 ) .

Table 1 2 . 2
U.S. PRESENT AND ESTIMATED FUTURE END USES OF SULFUR

1968 Year 2 0 0 0 Consumption

End Use m tons % Quantity (mt) %
Estimate low high

Fertilizers 4.550 50 16.800 12.000 22.300 56

Inorganic pigments .500 5 - - - 5
Cellulose fibres .570 6 2.000 1.500 2.000 5
Nonferrous metals .300 3 1.050 1.050 2.100 5
Explosives .250 2.6 .875 .700 1.050 3
Iron pickling .200 2.2 - - .020 0.06
Petroleum refining .180 2 .255 .325 .530 1.3
Alcohols .134 1.4 .470 .400 .500 1.5
Pulp and paper .540 6 1.900 .800 1.000 3
N e w & other uses 1.860 20 6.500 6.225 7.500 22
Total 9.085 30.000 23.000 37.000

After Hyne (1975).

282 SULFUR, ENERGY, AND ENVIRONMENT

future both in high intensity farming in industrial nations and in developing

nations such as India, Chapter 2. The use of sulfur in construction and
other non-chemical applications is covered in Chapter 14. It is dependent
on the fluctuation of the price correlation between sulfur and other bulk
materials. These prices, in turn, depend on the world economy, but are
also strongly susceptible to local conditions. During the next ten years
Canada and the Middle East will have relatively cheap sulfur available. In
France, the sulfur production is already decreasing and industry is
switching to high value thioorganics. The use of sulfur in polymers,
Chapter 13, is now well established. It is merely a matter of time before
this use becomes better recognized.

B. SULFURIC ACID

Table 12.3 shows the current trend in end use in sulfuric acid. The
price of sulfuric acid is strongly dependent on the purity and concentration.
The chemistry of sulfuric acid is reviewed in Sections 3C1 and 3C4. In
production catalysts are most important. Phillips of Bristol used platinum
as catalyst (B.P. 6,096, 1831). In 1875 Winkler published his work on
catalytic oxidation. In 1900 de Haen patented a vanadium catalyst
(D.P. 123,616) which was 150 times less effective than platinum but far
less sensitive to poisoning. Today, vanadium on a zeolite carrier is the
most commonly used material. Despite the highly reliable catalysts
available, catalyst poisoning constitutes an important economical factor.
Such poisoning has plagued all sulfur dioxide abatement processes aimed
at direct conversion of sulfur dioxide to acid.
The most thorough, reliable and useful summary of scientific and
technical data on sulfuric acid is still Duecker and West's book (1959).
Excellent information is also available in Ullmann's and Kirk-Othmer's
handbooks, in publications by Fasullo (1965), and and reports by Gardy
(1957), Sittig (1971), Slack (1971), and in pamphlets available from
manufacturers. The old monograph by Lunge (1909) still contains much
valuable information. Gmelin (1953) lists 17 other full sized books
exclusively devoted to sulfuric acid.
Sulfur acid can be mixed with water in any ratio. As mentioned, the
concentration is a very important factor in determining the value of
acid. Acid with less than 80% is far more corrosive (Fasullo, 1965),
Section 3C4, and, of course, more expensive to ship. Sulfuric acid cannot
be economically shipped further than a few hundred miles. About half of
 INTERMEDIATES 283

Table 1 2 . 3
TEN IMPORTANT END USES OF SULFURIC ACID (1970)

End Use 1000 t H2SO4

(100%)
Fertilizer
Phosphoric acid products 13,750
Normal superphosphate 1,240
Petroleum alkylation 2,400
Alcohols 1,800
Ti02 1,440
HF 880
Iron and steel pickling 800
Pulp and paper 600
Alum 600
Rayon 520

the world production of sulfuric acid is used by the producer. Unfortu-

nately, much of the acid which can be produced with present generation
sulfur dioxide abatement processes is only about 4 0 % pure. Thus, it is
useless for many applications either for chemical reasons or because of
transportation cost.
An excellent graph correlating material suitable for handling sulfuric
acid with temperature and acid strength has been prepared by Shell
(Stauffer, 1974). Acids containing more than 100% sulfuric acid, i.e. the
sulfuric acid to sulfur trioxide ratio is 1, are called fuming acid, or oleum.
They are prepared by mixing sulfur trioxide and sulfuric acid. The proper-
ties of sulfur trioxide are described in Section 3 C 1 . It is now sold and
shipped as a pure liquid (Stauffer, 1975). Detailed instructions for safe
shipping and use are now readily available.
Eighty percent of all acid goes into the production of phosphate
fertilizer, which follows the over-all scheme:

2Ca3(P04)2 + 6H2SO4 + I2H2O - > 6 C a S 0 4 ( H 2 0 ) 2 + 4H3PO4

C a 3( P 0 4 ) 2 + 4H3PO4 3 C a ( H 2P 0 4 ) 2

Phosphate rock Triple super phosphate

284 SULFUR, ENERGY, AND ENVIRONMENT

C. SULFUR DIOXIDE

The properties of sulfur dioxide have been described in Section 3C2

and are summarized in Table 3.12. Normally, sulfur dioxide is only used
as an intermediate for the production of sulfuric acid, because in other
applications it can be substituted by elemental sulfur which is far easier to
store and can be shipped at exactly half the weight of sulfur dioxide.
Sulfur dioxide can be produced from hydrogen sulfide and elemental sulfur
by burning. Sulfur dioxide is a large scale by-product of the smelting of
sulfide ores and of combustion of all fossile fuels, but it is almost always
converted to sulfuric acid or elemental sulfur, or released as a waste. A
family of processes for preparing sulfur dioxide from smelter gas has been
patented by ASARCO.
Recently, increased efforts have been made to find new uses for
sulfur dioxide. A potential prime application is in leaching of ores
(Habashi, 1976). Ramos (1976) estimates the yearly potential by 1985 of
other uses of sulfur dioxide as follows: 30 mil tons for water treatment,
30 mil tons for the manufacture of sugar, 120 mil tons for making agricul-
tural chemicals, and 25 mil tons for other uses, including wood pulping.
The toxic effects of sulfur dioxide are described in Chapter 10. Its
use in the food industry is described in Section 11C.

D. CARBON DISULFIDE

W. A. Lappadius discovered carbon disulfide in 1796 while super-

heating charcoal with elemental sulfur. Clement and Desormes described
the synthesis in 1803. In 1838 Schroeter set up the first continuous still.
The modern synthesis of carbon disulfide is based on work by C.B. Thaker
(U.S.P. 2,330,934, 1939), who found catalysts for the reaction:

CH4 + S4 -> CS2 + 2H2S

Belchetz patented a process for producing carbon disulfide from carbon

particles suspended in a sulfur gas stream (U.S.P. 2,487,039, Stauffer).
According to Fig. 7.4, the preheated vapor contains at 500°C comparable
amounts of several sulfur species such as S2, S3, S4, S5, S.5, S7, and Sg.
Carbon disulfide freezes at-112.1°C and boils at 46.25°C. The heat of
fusion is 13.8 kcal/kg, the heat of vaporization is 85.4 kcal/kg. Carbon
disulfide has an index of refraction of 1,62546 at 10°C; this value is 20
 INTERMEDIATES 285

times larger than that of water and gives the substance its characteristic
appearance.
Carbon disulfide has a flash temperature of -30°C; between 0.8
and 50% carbon disulfide explodes; the optimal combustion concentra-
tion is 6.8 volume %, i.e. 219 g/cubic meter. Above 95°C carbon dioxide
ignites spontaneously. The combustion of carbon disulfide has been well
studied. The solubility of carbon disulfide in water decreases from 2.04 g/1
at 0°C to 0.14 g at 5 0 ° . Below 03°C a white hydrate, [ 2 C S 2 - H 2 0 ] ,
precipitates. The following reactions are well known:

CS2 + H20 COS + H2S

CS2 + 2H20 C02 + 2H2S

With alcohols a xanthate is formed:

CS2 + ROH + NaOH -> H20 + RO-CS-SNa

These xanthates are used in the flotation of ore, and in the manufacture
of viscose. With chlorine, carbon tetrachloride is formed:

CS2 + 3Cl2 CI4 + S3Cl2

With alkali sulfides, trithiocarbonates are formed:

CS2 + K2S K2CS3

Carbon disulfide is used in the viscose industry to prepare cotton,

rayon, and other materials. World production is about 1 mil tons per year.

Toxicology

Carbon disulfide attacks the central nervous system, and in acute

cases acts as a narcotic which is swiftly followed by death. First symptoms
of poisoning are visual perturbation, i.e. veiling of objects, and a crawling
sensation in the skin. More than 10 ppm carbon disulfide induces chronic
poly neural damage; 100 ppm can cause acute psychosis and neural damage;
and more than 1000 ppm will cause delirious excitation. More than 3,000
ppm causes death.

E. CARBONYLSULFIDE, COS

Carbonylsulfide is not an important industrial chemical, but it consti-

tues a steady by-product in the oil and gas industry. It melts at -138.2°C,
286 SULFUR, ENERGY, AND ENVIRONMENT

boils at -50.2°C, and slowly reacts with the amines which are used as
absorber for hydrogen sulfide. COS is viciously poisonous; more so than
hydrogen sulfide, and it is more dangerous because it has no odor.

F. THIOPHOSGENE,CSCl 2

Thiophosgene melts at -110°C and boils at 73.5°C. The fuming, red

liquid is formed by reaction of carbon tetrachloride and hydrogen sulfide
at high temperature. It is used to prepare isocyanates which serve as
insecticides.

G. HYDROGEN SULFIDE, H 2 S

Hydrogen sulfide was discovered by Scheele (1777). Its composition

was recognized by Berthollet (1798), who gave it its present name.
Hydrogen sulfide is recovered from natural gas and is a by-product of ore
refineries. It is also prepared by acidification of sodium sulfide. It melts
at -85.6°C and boils at -60.38°C. The heat of melting is 568 cal/mole; the
heat of vaporization is 4.46 kcal/mole. More physical properties are listed
in Table 3.12. The solubility of hydrogen sulfide in water decreases from
6.87 g/100 ml to 1.23 g/100 ml at 100°C. The solubility in octane is
1.33 g/100 ml, in methanole 3.0 g/100 ml, and in benzene it is 25.1 g/100
ml. Hydrogen sulfide is too toxic and dangerous to be commercially used
on a large scale (Section 10B). Thus, neither commercial production nor
utilization are intentionally developed. Its properties are described in
Chapter 3. Its occurence as an intermediate is extensively discussed in
Chapter 5. The preparation of hydrogen sulfide from natural gas is
described in Chapter 7. The transportation has been discussed by Geddes
(1969).

H. SODIUM SULFIDE, N a 2 S

Sodium sulfide is a yellow solid which is hard to prepare in pure

form. The commercial form is N a 2 S - 9 H 2 0 , a colorless solid which melts
at 70°C. The substance is easily oxidized. The solubility increases from
16 g/100 ml at 2 0 ° to 40 g/100 ml at 90°C. Sodium sulfide is prepared
by reduction of N a 2 S 0 4 -
Na2SÛ4 + 2C ? -> N a 2 S + 2C02 - 48 kcal/mole
It can also be produced by electrolysis. The latter product is far more pure.
 INTERMEDIATES 287

Sodium Hydrosulfide

Sodium hydrosulfide is used more as a common commercial form

than sodium sulfide. It is prepared by absorption of hydrogen sulfide in
sodium hydroxide. It is shipped as a 4 5 % solution with a specific gravity
of 1.303 and a pH of 10.4. The viscosity is 7 centipoise. The solution
tends to crystallize below 6 2 ° F (17°C).
Sodium sulfide is used in the leather industry, for the flotation of
ores, in the paper industry, in oil refineries, to regenerate lead sulfite, and
in the organic industry. Details about handling and properties are given in
a brochure by Stauffer (1974).

I. SULFITE, HYDROSULFITE, PYROSULFITE, DISULFITE

The chemical properties of sulfite solutions have been reviewed in

Section 3B. An excellent detailed review is given by Gmelin (1953),
and in many other handbooks. Only commercial compounds are men-
tioned here:

1. A 1 2 ( S 0 3 ) 3
AÌ2(S03)3 is prepared by absorption of sulfur dioxide in solutions
containing A l ( O H ) n " 3 . It is also used to absorb sulfur dioxide in wash
n

towers; see Section 8D.

2. (NH4)2S03.H20
(NH4)2S03*H20 obtains by absorption of sulfur dioxide in ammonia
solution. At low temperature (NH4)2S03 is formed, at 100°C
(NH4)2S2Û5. Both oxidize in air to ammonium sulfate. The sulfite is
used for pulping. Very large quantities of ammonium sulfite or pyrosulfite
occur as intermediates in flue gas scrubbing, for example in the COMINCO
process. From these solutions sulfur dioxide can be regenerated, or
sulfate is produced for use as fertilizer.

3. C a S 0 3, CaHS03, C a 2 S 2 0 5
Calcium pyrosulfite is a major waste product in the present generation
'throw-away' processes which use limestone, lime, or half-calcined dolomite
to remove sulfur dioxide. The product crystallizes poorly, partly oxidizes
to sulfate, and must be stored in large, water tight ponds to reduce
leaching.
288 SULFUR, ENERGY, AND ENVIRONMENT

The setting and drying of these waste sludges is slow, because a solid
crust forms on the surface and prevents oxidation as well as crystallization.
A major research effort is under way to solve the problems of handling
such solutions, which constitute a major nuisance (Princiotta, 1976).

4. K 2 S 0 3 , KHSO3, K 2 S 2 0 5

Only potassium sulfite and pyrosulfite are known. The bisulfite is

more soluble than the pyrosulfite, and is not known in solid form.

5. K 2 S 2 O 5

s r e a r e
K2S2O5 is also incorrectly labelled KHSO3. ^ * P P d by
saturating a strong solution of KOH with sulfur dioxide at 80°C. A
solution with 60-62% K2S2O5 can be obtained. Carefully crystallized,
pure K2S2O5 is used in the food industry as a preservative (Section 11C),
in agriculture, and for sterilizing wine and brandy.

6. N a 2 S 0 3

Sodium sulfite, with the formula N a 2 S 0 3 ' 7 H 2 0 is prepared at 4 0 ° C

by dissolving sulfur dioxide in NaOH. It also is recovered during the prep-
aration of phenol. It is used in the food industry, photographic industry,
as antichlor in textile bleaching, and for preparing sodium bisulfate.

7. N a 2 S 2 0 5

Sodium pyrosulfite, often mislabelled 'sodium bisulfite, NaHS03* is

obtained from soda or sodium hydroxide solutions. It is used for tanning,
to purify aldehydes, for making glues, in the paper industry, and to
prevent the yellowing of foods and as a preservative.

8. M g S 0 3 6 H 2 0

This material crystallizes from the dolomite solutions used to treat

flue gases. The disposal of MgSÛ3 is a major problem, as discussed for
C a S 0 3 . Regeneration of the calcium oxide by thermal decomposition can
be achieved at 1000°C, but the energy needed is exorbitant.

9. 2 Z n S 0 3 - 5 H 2 0

This material is obtained if ZnO is used to strip flue gases. The salt
decomposes at 260°C; thus, regeneration is feasible.
 INTERMEDIATES 289

Κ. SODIUM THIOSULFATE, N a 2 S 2 0 3

Sodium thiosulfate was discovered by L. N. Vauquelin in 1802 in the

residue of Leblanc-soda solutions. It was originally called 'hyposulfite.'
The name has been preserved in the photography industry and among
photographers who use it to fix the image in film developing. It acts by
complexing the unreacted silver ion. For this purpose, it must be very
pure and must be free of heavy ions and sulfite. Normal commercial
thiosulfate is 98% pure. It is used t o remove excess chlorine in paper and
textile bleaching ('antichlor'), to extract silver from ore, t o prepare
matches, to preserve soap, and in organic industry. Annual world produc-
tion is about 50,000 tons. It can be prepared by oxidation of sulfides, the
reaction of sulfur dioxide on sulfides, and the reaction of sulfite with
elemental sulfur between 60 and 100°C. The latter method can be used
to prepare concentrated solutions. Originally, it was largely obtained
from C a ( H S ) 2 , which is a by-product of the Leblanc-soda process.

(NH4)2S203

This material is prepared by reaction of sodium thiosulfate with

ammonium chloride, or by the reaction of ammonium sulfite with ele-
mental sulfur. It is used as a rapid fixer in photography.

L. POTASSIUM POLYTHIONATES, K 2 S n 0 6

Potassium polythionates occur as intermediates in some sulfur dioxide

abatement reactions. The structure and reaction are discussed in Section
Three C. The only practical use is as a substitute for colloidal sulfur in
dermatology, Chapter 10.

M. SODIUM DITHIONITE, N a 2 S 2 0 4 2 H 2 0

Sodium dithionites are also called 'hydrosulfite.' They acquired the

name before their structure was known. The chemistry of these com-
pounds is discussed in Section 3B. The solubility increases from 20g/100
ml at 15°C to 44 g/100 ml at 75°C. However, the dithionite decomposes
rapidly above 50°C. The decomposition is catalyzed by thiosulfate and
polysulfide. If air is excluded and the pH is kept at 8-9, dithionite
solutions are stable for several days at room temperature.
290 SULFUR, ENERGY, AND ENVIRONMENT

Dithionite is prepared with zinc, with sodium amalgam, or with

formic acid, Chapter 3B. It is used as a reducing agent and as a bleaching
agent for wool, cotton, sugar, cooking oil, and gelatin. Common stabilizers
are the polyphosphates. Annual world production is about 100,000 tons.

N. SODIUM HYDROXYMETHANESULFINATE

NaS02*CH20H-2H20 is prepared by reaction of dithionite with

formaldehyde in the presence of alkali. This compound, with the trade-
name 'Rongalite,' is used in printing and for forming polymers, Chapter 1 3 .

O. DISULFUR DICHLORIDE, S 2 C l 2

'Sulfur monochloride,' i.e. disulfur dichloride ('sulfur monochloride,

SCI2, is monosulfur dichloride) is used as an additive to lubricants, in
drilling muds, and in organic reactions. Its technical use is described in a
brochure (Stauffer, 1976). It reacts with water, yielding sulfur dioxide
and sulfur. With ammonia N4S4 is formed. In organic chemistry it acts
as a chlorinating agent. Disulfur dichloride can react with sulfur and
give a mixture of chlorosulfanes, S x Cl2 with a value of χ between 2 and 8,
see Section 3A. The main use is for vapor phase vulcanization of rubber,
Section 13F. The physical properties are described in Table 3.12.
Organosulfur compounds are becoming increasingly important.
Among the many important compounds are methylmercaptan, methyl
mercaptopropionaldehyde, which is used t o synthesize methiomine,
Chapter 1 1 , heavy linear mercaptans with C3 t o C j 2 which are used as
transfer chain agents in styrene and butadiene polymerization, thioglycolic
acid which is used to make intermediates for pharmaceuticals and cos-
metics, and polysulfides which are used as asphalt binders, sealants, and
for other purposes, Chapter 1 3 . All these compounds are still primarily
specialty chemicals with prices up to $2 per pound, because the useful-
ness of bulk thioorganic chemicals is n o t yet fully recognized. It can be
anticipated that in the n o t t o o distant future thioorganics will become
more important and more widely used.