CAS No. 74-86-2

Formula: C2H2
Basic Info

Acetylene (systematic name: ethyne) is the chemical compound with the formula C2H2. It is a hydrocarbon and the simplest alkyne. This colorless gas is widely used as a fuel and a chemical building block. It is unstable in its pure form and thus is usually handled as a solution. Pure acetylene is odorless, but commercial grades usually have a marked odor due to impurities.
As an alkyne, acetylene is unsaturated because its two carbon atoms are bonded together in a triple bond. The carbon–carbon triple bond places all four atoms in the same straight line, with CCH bond angles of 180°.

Molecular Weight
Exact Mass

Welding Gas









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Appearance & Physical State
A colorless gas with a faint garlic-like odor.
0.568 g/cm3
Boiling Point
Melting Point
Flash Point
Refractive Index
Water Solubility
0.106 g/100 mL
High in closed containers. Highly reactive; all mixtures of C2H2 (water saturated) in air can be exploded at pressures above 2 atmospheres.
Storage Condition
Keep in a cool, dry, dark location in a tightly sealed container or cylinder. Keep away from incompatible materials, ignition sources and untrained individuals. Secure and label area. Protect containers/cylinders from physical damage.
Safety Info
Safety Statements
Risk Statements
HS Code
UN 1001
Hazard Class
Hazard Codes
SDS 1.0
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According to Globally Harmonized System of Classification and Labelling of Chemicals (GHS) - Sixth revised edition

Version: 1.0

Creation Date: Aug 14, 2017

Revision Date: Aug 14, 2017


1.1 GHS Product identifier

Product name acetylene

1.2 Other means of identification

Product number -
Other names Welding Gas

1.3 Recommended use of the chemical and restrictions on use

Identified uses For industry use only. Agricultural chemicals (non-pesticidal),Fuels and fuel additives,Intermediates,Processing aids, not otherwise listed
Uses advised against no data available

1.4 Supplier's details

Company MOLBASE (Shanghai) Biotechnology Co., Ltd.
Address Floor 4 & 5, Building 12, No. 1001 North Qinzhou Road,
Xuhui District, Shanghai, China
Telephone +86(21)64956998
Fax +86(21)54365166

1.5 Emergency phone number

Emergency phone number +86-400-6021-666
Service hours Monday to Friday, 9am-5pm (Standard time zone: UTC/GMT +8 hours).

2.Hazard identification

2.1 Classification of the substance or mixture

Gases under pressure: Compressed gas

Flammable gases, Category 1

2.2 GHS label elements, including precautionary statements

Signal word


Hazard statement(s)

H220 Extremely flammable gas

Precautionary statement(s)

P210 Keep away from heat, hot surfaces, sparks, open flames and other ignition sources. No smoking.


P377 Leaking gas fire: Do not extinguish, unless leak can be stopped safely.

P381 In case of leakage, eliminate all ignition sources.


P410+P403 Protect from sunlight. Store in a well-ventilated place.

P403 Store in a well-ventilated place.



2.3 Other hazards which do not result in classification


3.Composition/information on ingredients

3.1 Substances

Chemical name Common names and synonyms CAS number EC number Concentration
acetylene acetylene 74-86-2 none 100%

4.First-aid measures

4.1 Description of necessary first-aid measures

General advice

Consult a physician. Show this safety data sheet to the doctor in attendance.

If inhaled

Fresh air, rest. Artificial respiration may be needed. Refer for medical attention.

In case of skin contact

Wash off with soap and plenty of water. Consult a physician.

In case of eye contact

First rinse with plenty of water for several minutes (remove contact lenses if easily possible), then refer for medical attention.

If swallowed

Never give anything by mouth to an unconscious person. Rinse mouth with water. Consult a physician.

4.2 Most important symptoms/effects, acute and delayed

Headache, dizziness and loss of consciousness may occur. Death from ``smothering'' may occur if oxygen content of the air is severely reduced by dilution with acetylene. (USCG, 1999)

4.3 Indication of immediate medical attention and special treatment needed, if necessary

Immediate first aid: Ensure that adequate decontamination has been carried out. If patient is not breathing, start artificial respiration, preferably with a demand valve resuscitator, bag-valve-mask device, or pocket mask, as trained. Perform CPR if necessary. Immediately flush contaminated eyes with gently flowing water. Do not induce vomiting. If vomiting occurs, lean patient forward or place on the left side (head-down position, if possible) to maintain an open airway and prevent aspiration. Keep patient quiet and maintain normal body temperature. Obtain medical attention. /Aliphatic hydrocarbons and related compounds/

5.Fire-fighting measures

5.1 Extinguishing media

Suitable extinguishing media

Stop flow of gas before extinguishing fire. Use water spray to keep fire-exposed containers cool. Approach fire from upwind to avoid hazardous vapors and toxic decomposition products. Fight fire from protected location or maximum possible distance. Use water spray, dry chemical, form, or carbon dioxide. /Acetylene, dissolved/

5.2 Specific hazards arising from the chemical

Behavior in Fire: May explode in fire (USCG, 1999)

5.3 Special protective actions for fire-fighters

Wear self-contained breathing apparatus for firefighting if necessary.

6.Accidental release measures

6.1 Personal precautions, protective equipment and emergency procedures

Use personal protective equipment. Avoid dust formation. Avoid breathing vapours, mist or gas. Ensure adequate ventilation. Evacuate personnel to safe areas. Avoid breathing dust. For personal protection see section 8.

6.2 Environmental precautions

Remove all ignition sources. Evacuate danger area! Consult an expert! Personal protection: self-contained breathing apparatus. Ventilation.

6.3 Methods and materials for containment and cleaning up

Evacuate danger area! Consult an expert! Ventilation. Remove all ignition sources. (Extra personal protection: self-contained breathing apparatus).

7.Handling and storage

7.1 Precautions for safe handling

Avoid contact with skin and eyes. Avoid formation of dust and aerosols. Avoid exposure - obtain special instructions before use.Provide appropriate exhaust ventilation at places where dust is formed. For precautions see section 2.2.

7.2 Conditions for safe storage, including any incompatibilities

Fireproof. See Chemical Dangers. Cool.Keep container in a cool, well-ventilated area. Keep container tightly closed and sealed until ready for use. Avoid all possible sources of ignition (spark or flame). Segregate from oxidizing materials. Cylinders should be stored upright, with valve protection cap in place, and firmly secured to prevent falling or being knocked over. Cylinder temperatures should not exceed 52 degC (125 degF).

8.Exposure controls/personal protection

8.1 Control parameters

Occupational Exposure limit values

Recommended Exposure Limit: Ceiling Value: 2500 ppm (2662 mg/cu m).

Biological limit values

no data available

8.2 Appropriate engineering controls

Handle in accordance with good industrial hygiene and safety practice. Wash hands before breaks and at the end of workday.

8.3 Individual protection measures, such as personal protective equipment (PPE)

Eye/face protection

Safety glasses with side-shields conforming to EN166. Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (US) or EN 166(EU).

Skin protection

Wear impervious clothing. The type of protective equipment must be selected according to the concentration and amount of the dangerous substance at the specific workplace. Handle with gloves. Gloves must be inspected prior to use. Use proper glove removal technique(without touching glove's outer surface) to avoid skin contact with this product. Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices. Wash and dry hands. The selected protective gloves have to satisfy the specifications of EU Directive 89/686/EEC and the standard EN 374 derived from it.

Respiratory protection

Wear dust mask when handling large quantities.

Thermal hazards

no data available

9.Physical and chemical properties

Physical state A colorless gas with a faint garlic-like odor.
Colour Colorless gas ... [Note: Shipped under pressure dissolved in acetone]
Odour Not unpleasant odor unless impure (due to phosphine)
Melting point/ freezing point -88ºC
Boiling point or initial boiling point and boiling range -28ºC
Flammability Flammable GasExtremely flammable.
Lower and upper explosion limit / flammability limit Lower flammable limit: 2.5% by volume; Upper flammable limit: 100% by volume
Flash point -18ºC
Auto-ignition temperature 305°C (USCG, 1999)
Decomposition temperature no data available
pH no data available
Kinematic viscosity no data available
Solubility In water:0.106 g/100 mL
Partition coefficient n-octanol/water (log value) log Kow = 0.37
Vapour pressure 44.2 atm (NIOSH, 2016)
Density and/or relative density 0.568 g/cm3
Relative vapour density 0.91 (Air = 1)
Particle characteristics no data available

10.Stability and reactivity

10.1 Reactivity

no data available

10.2 Chemical stability

Stability during transport: Stable as shipped.

10.3 Possibility of hazardous reactions

Very dangerous fire hazard when exposed to heat or flame ...The gas mixes well with air, explosive mixtures are easily formed.ACETYLENE reacts with alkali metals, forming hydrogen gas. Acetylene can react explosively with bromine [Von Schwartz 1918. p.142]. Acetylene forms a sensitive acetylide when passed into an aqueous solution of mercuric nitrate [Mellor 4:933. 1946-47]. It reacts with silver, copper and lead to form sensitive, explosive salts. Since acetylene is endothermic and effectively a reducing agent, its reaction with oxidants can be very violent (examples: calcium hypochlorite, nitric acid, nitrogen oxide, ozone, trifluoromethyl hypofluorite, etc.). Contact of very cold liquefied gas with water may result in vigorous or violent boiling of the product and extremely rapid vaporization, due to the large temperature differences involved. If the water is hot, there is the possibility that a liquid "superheat" explosion may occur. Pressures may build to dangerous levels if liquid gas contacts water in a closed container [Handling Chemicals Safely 1980]. Acetylene and ammonia can form explosive silver salts in contact with Ag. (Renner, Hermann, Gunther Schlamp. "Silver, Silver Compounds, and Silver Alloys." Ullmann's Encyclopedia of Industrial Chemistry. Wiley-VCH Verlag GmbH & Co. KGaA. 2001.).

10.4 Conditions to avoid

no data available

10.5 Incompatible materials

Mixture with air containing between 3-82% gas is explosive. Contact with /bleaching powder may lead to formation of explosive chloroacetylenes. Finely divided /cobalt/ metal decomposes and polymerizes acetylene on contact, becoming incandescent. Copper metal forms explosive compounds with acetylene. If warmed in air or oxygen, or on impact, copper acetylides may explode in subsequent contact with acetylene. Interaction with /halogens/ can be violent or explosive. Contact of acetylene with concentrated nitric acid in presence of mercury forms explosive trinitromethane or tetranitromethane if sulfuric acid is subsequently added. Mixture with /nitric oxide products/ will ignite at +30-50°C. Mixtures with /oxygen/ are very explosive even at very low oxygen concentrations (<2.5%). Molten /potassium/ ignites in acetylene, then explodes. /Silver/ forms explosive compounds with acetylene. Interaction with /trifluoromethyl hypofluorite/, in absence of nitrogen as diluent, is explosive on mixing.

10.6 Hazardous decomposition products

/Acetylene/, the extremely endothermic gas ... may decomposed explosively in absence of air ... /and/ readily escalates to detonation in tubular vessels. This type of explosive decomposition has been experienced in a 7 mile acetylene pipeline system ... Accidental local heating to 185°C or above of part of the wall (as little as 6 sq cm may be enough) of a cylinder containing acetylene may lead to the development of an extremely dangerous situation. At this temperature, exothermic and self-sustaining decomposition of (endothermic) acetylene may set in, and if not stopped by rapid and effective cooling (large volume water spray), the cylinder may explode without warning. Flame flash-back into a cylinder from a wrongly adjusted and/or damaged welding or cutting torch can cause the same effect ...

11.Toxicological information

Acute toxicity

  • Oral: no data available
  • Inhalation: no data available
  • Dermal: no data available

Skin corrosion/irritation

no data available

Serious eye damage/irritation

no data available

Respiratory or skin sensitization

no data available

Germ cell mutagenicity

no data available


no data available

Reproductive toxicity

no data available

STOT-single exposure

no data available

STOT-repeated exposure

no data available

Aspiration hazard

no data available

12.Ecological information

12.1 Toxicity

  • Toxicity to fish: no data available
  • Toxicity to daphnia and other aquatic invertebrates: no data available
  • Toxicity to algae: no data available
  • Toxicity to microorganisms: no data available

12.2 Persistence and degradability

AEROBIC: Acetylene, present at 1.6 mg/L, reached 0% of its theoretical BOD in 28 days using an activated sludge inoculum in the Japanese MITI test(1).

12.3 Bioaccumulative potential

An estimated BCF of 3 was calculated in fish for acetylene(SRC), using a log Kow of 0.37(1) and a regression-derived equation(2). According to a classification scheme(2), this BCF suggests the potential for bioconcentration in aquatic organisms is low(SRC).

12.4 Mobility in soil

The Koc of acetylene is estimated as 2(SRC), using a log Kow of 0.37(1) and a regression-derived equation(2). According to a classification scheme(3), this estimated Koc value suggests that acetylene is expected to have very high mobility in soil. Less than 1 ppm of gas acetylene was absorbed to dry soil and a maximum of 90 ppm of acetylene was absorbed to moist soil samples taken from 6 soil samples from Oregon, Iowa and Saskatchewan, Canada(4).

12.5 Other adverse effects

no data available

13.Disposal considerations

13.1 Disposal methods


The material can be disposed of by removal to a licensed chemical destruction plant or by controlled incineration with flue gas scrubbing. Do not contaminate water, foodstuffs, feed or seed by storage or disposal. Do not discharge to sewer systems.

Contaminated packaging

Containers can be triply rinsed (or equivalent) and offered for recycling or reconditioning. Alternatively, the packaging can be punctured to make it unusable for other purposes and then be disposed of in a sanitary landfill. Controlled incineration with flue gas scrubbing is possible for combustible packaging materials.

14.Transport information

14.1 UN Number

ADR/RID: UN1001 IMDG: UN1001 IATA: UN1001

14.2 UN Proper Shipping Name


14.3 Transport hazard class(es)

ADR/RID: 2.1 IMDG: 2.1 IATA: 2.1

14.4 Packing group, if applicable

ADR/RID: unknown IMDG: unknown IATA: unknown

14.5 Environmental hazards

ADR/RID: no IMDG: no IATA: no

14.6 Special precautions for user

no data available

14.7 Transport in bulk according to Annex II of MARPOL 73/78 and the IBC Code

no data available

15.Regulatory information

15.1 Safety, health and environmental regulations specific for the product in question

Chemical name Common names and synonyms CAS number EC number
acetylene acetylene 74-86-2 none
European Inventory of Existing Commercial Chemical Substances (EINECS) Listed.
EC Inventory Listed.
United States Toxic Substances Control Act (TSCA) Inventory Listed.
China Catalog of Hazardous chemicals 2015 Listed.
New Zealand Inventory of Chemicals (NZIoC) Listed.
Philippines Inventory of Chemicals and Chemical Substances (PICCS) Listed.
Vietnam National Chemical Inventory Listed.
Chinese Chemical Inventory of Existing Chemical Substances (China IECSC) Listed.

16.Other information

Information on revision

Creation Date Aug 14, 2017
Revision Date Aug 14, 2017

Abbreviations and acronyms

  • CAS: Chemical Abstracts Service
  • ADR: European Agreement concerning the International Carriage of Dangerous Goods by Road
  • RID: Regulation concerning the International Carriage of Dangerous Goods by Rail
  • IMDG: International Maritime Dangerous Goods
  • IATA: International Air Transportation Association
  • TWA: Time Weighted Average
  • STEL: Short term exposure limit
  • LC50: Lethal Concentration 50%
  • LD50: Lethal Dose 50%
  • EC50: Effective Concentration 50%


  • IPCS - The International Chemical Safety Cards (ICSC), website:
  • HSDB - Hazardous Substances Data Bank, website:
  • IARC - International Agency for Research on Cancer, website:
  • eChemPortal - The Global Portal to Information on Chemical Substances by OECD, website:
  • CAMEO Chemicals, website:
  • ChemIDplus, website:
  • ERG - Emergency Response Guidebook by U.S. Department of Transportation, website:
  • Germany GESTIS-database on hazard substance, website:
  • ECHA - European Chemicals Agency, website:

Disclaimer: The above information is believed to be correct but does not purport to be all inclusive and shall be used only as a guide. The information in this document is based on the present state of our knowledge and is applicable to the product with regard to appropriate safety precautions. It does not represent any guarantee of the properties of the product. We as supplier shall not be held liable for any damage resulting from handling or from contact with the above product.
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