Description
Ethane thiol, commonly known as ethyl mercaptan, is a colorless gas or clear liquid with a distinct odor. It is an organosulfur compound with the formula CH
3CH
2SH. Abbreviated EtSH, it consists of an ethyl group (Et), CH
3CH
2, attached to a thiol group, SH. Its structure parallels that of ethanol, but with S instead of O. The odor of EtSH is infamous. Ethanethiol is more volatile than ethanol due to a diminished ability to engage in hydrogen bonding. Ethanethiol is toxic. It occurs naturally as a minor component of petroleum, and may be added to other wise odorless gaseous products such as liquefied petroleum gas (LPG) to help warn of gas leaks. At these concentrations, ethanethiol is not harmful.
Chemical Properties
A yellowish liquid (or a colorless gas above the BP). fruity, sulfur aroma. Strong, sharp odor of garlic or skunklike odor.
Physical properties
Colorless liquid with a strong, disagreeable, skunk-like or rotten egg odor. Extremely flammable
liquid or gas. An experimentally determined odor threshold concentration of 1 ppb
v was reported
by Leonardos et al. (1969). Katz and Talbert (1930) reported experimental detection odor
threshold concentrations in the range 0.66–7.6 μg/m
3 (0.26 to 3.0 ppb
v).
Uses
Stenching agent for liquefied petroleum
gases; adhesive stabilizer; manufacture of
plastics, insecticides, and antioxidants
Uses
LPG odorant, adhesive, stabilizer, chemical
intermediate.
Uses
Ethanethiol is used as an intermediate inthe manufacture of insecticides, plastics, andantioxidants; and as an additive to natural gasto give odor. It occurs in illuminating gas andin petroleum distillates.
Production Methods
Ethyl mercaptan is prepared by distilling ethyl potassium sulfate with potassium hydrogen sulfide. Additional mercaptans can be prepared in a similar manner with the corresponding proper ingredients.
Definition
ChEBI: Ethanethiol is an alkanethiol that is ethane substituted by a thiol group at position 1. It is added to odorless gaseous products such as liquefied petroleum gas (LPG) to provide a garlic scent which helps warn of gas leaks. It has a role as a rodenticide.
Application
Ethanethiol can be used as a reactant for the synthesis of:
Functionalized oxazolidinones by conjugated nucleophilic addition- electrophilic amination reaction.
Ethyl phenyl sulfide by C-S coupling with iodobenzene.
Chain transfer agent in the RAFT polymerization of N-isopropylacrylamide.
Preparation
Ethanethiol is prepared by the reaction of ethylene with hydrogen sulfide over a catalyst. The various producers utilize different catalysts in this process. It is also be prepared commercially by the reaction of ethanol with hydrogen sulfide gas over an acidic solid catalyst, such as alumina.
Ethanethiol was originally reported by Zeiss in 1834 . Zeise treated calcium ethyl sulfate with a suspension of barium sulfide saturated with hydrogen sulfide. He is credited with naming the C
2H
5S- group as mercaptum.
Ethanethiol can also be prepared by a halide displacement reaction, where ethyl halide is reacted with aqueous sodium bisulfide. This conversion was demonstrated as early as 1840 by Henri Victor Regnault.
Reactions
Ethane thiol is a valued reagent in organic synthesis. In the presence of sodium hydroxide, it gives the powerful nucleophile SEt-. The salt can be generated quantitatively by reaction with sodium hydride.
Ethane thiol can be oxidized to ethyl sulfonic acid, using bleach and related strong aqueous oxidants. Weaker oxidants, such as ferric oxide give the disulfide, diethyl disulfide :
2 EtSH + H
2O
2 → EtS-SEt + 2 H
2O
Like other thiols, it behaves comparably to hydrogen sulfide. For example, it binds, concomitant with deprotonation to "soft" transition metal cations, such as Hg
2+, Cu
+, and Ni
2+ to give polymeric thiolato complexes, Hg(SEt)
2, CuSEt, and Ni(SEt)
2, respectively.
Aroma threshold values
High strength odor, sulfurous fruity type; recommend smelling in a 0.01% solution or less.
General Description
A clear colorless low-boiling liquid (boiling point 97°F) with an overpowering, garlic-like/skunk-like odor. Flash point -55°F. Less dense than water and very slightly soluble in water. Vapors are heavier than air. Vapors may irritate nose and throat. May be toxic if swallowed, by inhalation or by contact. Added to natural gas as an odorant. Used as a stabilizer for adhesives.
Air & Water Reactions
Highly flammable. A very dangerous fire hazard. Very slightly soluble in water.
Reactivity Profile
Ethanethiol reacts violently with calcium hypochlorite, May react vigorously with other oxidizing reagents. On contact with strong acids or when heated to decomposition Ethanethiol emits highly toxic fumes of sulfur oxides [Sax, 9th ed., 1996, p. 1575].
Hazard
Toxic by ingestion and inhalation.
Flammable, dangerous fire risk.
Health Hazard
Inhalation of vapor causes muscular weakness, convulsions, respiratory paralysis. High concentrations may cause pulmonary irritation. Liquid irritates eyes and skin. Ingestion causes nausea and irritation of mouth and stomach.
Health Hazard
The inhalation toxicity of ethanethiol islower than that of methanethiol. Intraperitoneal administration in rats at sublethaldoses caused deep sedation, followed bylethargy, restlessness, lack of muscular coordination, and skeletal muscle paralysis.Higher doses produced cyanosis, kidney andliver damage, respiratory depression, coma,and death. The intraperitoneal LD50 value inrats was 450 mg/kg (ACGIH 1986).Ethanethiol is metabolized to inorganicsulfate and ethyl methyl sulfone, and excreted. The oral LD50 value in rats is 680 mg/kg.In humans, repeated exposures to itsvapors at about 5 ppm concentration canproduce irritation of the nose and throat,headache, fatigue, and nausea.
Chemical Reactivity
Reactivity with Water No reaction; Reactivity with Common Materials: No reaction; Stability During Transport: Stable; Neutralizing Agents for Acids and Caustics: Not pertinent; Polymerization: Not pertinent; Inhibitor of Polymerization: Not pertinent.
Safety Profile
Moderately toxic by
ingestion, inhalation, and intraperitoneal
routes. A skin and eye irritant. Inhalation
causes central nervous system effects in
humans. A very dangerous fire hazard when
exposed to heat or flame; can react
vigorously with oxidizing materials. A
moderate explosion hazard when exposed to
spark or flame. Violent reaction with
Ca(OCl)2. Will react with water or steam to
produce toxic and flammable vapors. To
fight fire, use CO2, dry chemical. When
heated to decomposition or on contact with
acid or acid fumes it emits hghly toxic
fumes of SOx. See also MERCAPTANS.
Potential Exposure
This material is used as a warning
odorant for liquefied petroleum gases. It is used as an intermediate in the manufacture of many pesticides and other
organic chemicals
Environmental Fate
Biological. Ethyl mercaptan did not degrade in anaerobic sediments and sludges nor in
anaerobic freshwater conditions (van Leerdam et al., 2006).
Photolytic. A second-order rate constant of 1.21 x 10
-12 cm
3/moleculesec was reported for the
reaction of ethyl mercaptan and NO3 radicals in the atmosphere at 297 K (Atkinson, 1991).
Chemical/Physical. In the presence of nitric oxide, ethyl mercaptan reacted with OH radicals
forming ethyl thionitrite. The rate constant for this reaction is 2.7 x 10
-11 at 20 °C (MacLeod et al.,
1984).
Shipping
UN2363 Ethyl mercaptan, Hazard Class: 3;
Labels: 3-Flammable liquid
Purification Methods
Dissolve the thiol in aqueous 20% NaOH, extract it with a small amount of *benzene and then steam distil until clear. After cooling, the alkaline solution is acidified slightly with 15% H2SO4 and the thiol is distilled off, dried with CaSO4, CaCl2 or 4A molecular sieves, and fractionally distilled under nitrogen [Ellis & Reid J Am Chem Soc 54 1674 1932]. It has a foul odour. [Beilstein 1 IV 1390.]
Incompatibilities
May form explosive mixture with air.
Slowly forms peroxides. This material is a weak acid.
Reacts with oxidizers, causing fire and explosion hazard.
Reacts with strong acids evolving toxic and flammable
hydrogen sulfide. May accumulate static electrical charges,
and may cause ignition of its vapors. Attacks some forms
of plastics, coatings and rubber. Aldehydes are frequently
involved in self-condensation or polymerization reactions.
These reactions are exothermic; they are often catalyzed by
acid. Aldehydes are readily oxidized to give carboxylic
acids. Flammable and/or toxic gases are generated by the
combination of aldehydes with azo, diazo compounds,
dithiocarbamates, nitrides, and strong reducing agents.
Aldehydes can react with air to give first peroxo acids, and
ultimately carboxylic acids. These autoxidation reactions
are activated by light, catalyzed by salts of transition
metals, and are autocatalytic (catalyzed by the products of
the reaction). The addition of stabilizers (antioxidants) to
shipments of aldehydes retards autoxidation
Toxics Screening Level
The initial threshold screening level (ITSL) for ethyl mercaptan (CAS # 75-08-1) is 13 μg/m3 with
a 1-hour averaging time.
Waste Disposal
Incineration (1093℃) followed by scrubbing with a caustic solution
