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1. Dimethyl Disulfide
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2. DMDS can be produced by the oxidation of methanethiol, e.g. with iodine:
2 CH3SH + I2 → CH3SSCH3 + 2 HI
Chemical reactions
Important reactions include chlorination giving methanesulfenyl chloride (CH3SCl),
methanesulfinyl chloride (CH3S(O)Cl),[4] and methanesulfonyl chloride (CH3SO2Cl) as well as
oxidation with hydrogen peroxide or peracetic acid giving the thiosulfinate methyl
methanethiosulfinate (CH3S(O)SCH3)
Dimethyl disulfide (DMDS) is an organic chemical compound with the molecular formula
CH3SSCH3 which is the simplest disulfide. It is a flammable liquid with an unpleasant, garlic-like
odor. DMDS is used in the petrochemical industry for oil-refining and the production of low sulfur
fuels. It is also used to make a variety of important chemicals in the chemical industry, as a solvent
and as an anti-corrosion agent in metallic machinery.

4. Technical and economic evaluation of separation of dimethyl disulfide from
disulfide oil at liquefied petroleum gas treatment facilities of Assaluyeh gas
refinery

5. Dimethyl Disulfide (DMDS)
Dimethyl Disulfide (DMDS) is the most commonly used chemical for
sulfiding hydrotreating and hydrocracking catalysts. These
hydroprocessing catalysts contain metal oxides that must be converted
to the active metal sulfide before they will promote desulfurization and
denitrification reactions on hydrocarbon feeds. The activation process,
often called presulfiding, begins with the introduction of DMDS into a
reactor pressurized with hydrogen at a temperature of 370F or higher.
Under these conditions and when exposed to a hydrotreating catalyst,
DMDS rapidly decomposes, forming the H2S required to convert the
oxides to metal sulfides.

6. Production method for dimethyl disulfide
Abstract
The invention relates to a production method for dimethyl disulfide. The
production method comprises the following steps: subjecting methyl
mercaptan and strong base to reaction so as to generate methanthiol salt,
and subjecting methanthiol salt and oxygen-containing gas to oxidation
reaction so as to prepare dimethyl disulfide. The method provided by the
invention combines a caustic soda liquid absorption method and an
oxidation method to realize preparation of dimethyl disulfide, and has the
advantages of small explosive range, basically no by-product, high
product purity, high yield, etc.

7. Technology Transfer options:
Licensing from Manufacturer
Technology from Patent Owners

8. Food and Nutrition
To help the agricultural industry flourish in its efforts to maintain fertile land, grow crops and raise
healthy livestock ; agrochemical intermediates -Dimethyl Disulfide.
Dimethyl Disulfide is also used as a flavor and fragrance intermediate, which enriches the aroma and
flavor of certain consumer products.

9. Refinery Applications
Dimethyl Disulfide (DMDS) is a sulfiding
agent, which is used along with a reducing
agent such as hydrogen, to transform metal
oxide species to a metallic sulfide crystalline
phase in situ for hydrotreating catalysts. For in
situ sulfiding, the reaction is performed inside
the process unit for complete control and to
achieve maximum catalyst activity and safe
handling.
DMDS can also be used as a passivation
agent to reduce the layer of coke that forms
within furnaces and improve the run length,
yield and life of furnaces.
DMDS (dimethyl disulfide) is the most
common compound used for
hydrocracking catalysts sulfiding in
refineries. DMDS (dimethyl disulfide) in
petrochemical is injected continously at
low rate in ethylene crackers. It prevents
coke formation and mitigates CO
formation. Arkema is worldwide leader for
production and sales of dimethyl
disulfide (DMDS).

10. Advantages
Compared to other sulfiding agents, DMDS has the
highest sulfur content, which reduces the amount of
product required for converting oxides to active metal
sulfides. Thermally stable with low viscosity, DMDS is
suitable for gas- or liquid-phase injection. It begins to
decompose to H2S at low temperatures, so the risks of
reducing the metal oxides prior to sulfiding are
eliminated. In addition, DMDS also decomposes in two
steps, further minimizing the risk of temperature
excursions during sulfiding.

11. Packaging
DMDS is available in
bulk (railcars, tank trucks
and ISO containers) or
packaged containers
including 250 gallon
returnable steel totes,
57 gallon returnable
steel cylinders or 54
gallon drums.

12. Safety and Handling
Due to its low vapor pressure, DMDS is a safe product to
handle at high ambient temperatures. However, it also
has a low flash point and should be handled as a
flammable material—stored under inert conditions and
away from potential ignition sources. DMDS is a dermal,
oral and toxic inhalation material, as well as a marine
pollutant. It also may have a slightly unpleasant odor.
DMDS generates methane during the sulfiding
operation, which if not handled properly, may require
purging and undesired SOx emissions. DMDS is not
soluble with water, but will solubilize in both amines and
ketones. DMDS is compatible with both carbon and
stainless steel as long as excess water is not present.

14. Some of the key players operating in the Dimethyl
Disulfide Market around the globe include Chevron
Phillips Chemical Company LLC., IRO Group Inc., Shinya
Chem Co., Ltd., Arkema S.A., Hangzhou Rongshunjia
Technology Co., Ltd., Haihang Industry Co., Ltd., Varsal,
Inc., Penta International Corporation, Alpha Chemika,
Tianjin TopGlobal Co., Ltd., and Others.

16. DimethylDisulfide
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