How do I get propyne from acetylene

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Chemical Datasheet


Chemical Identifiers | Hazards | Response Recommendations | Physical Properties | Regulatory Information | Alternate Chemical Names

Chemical Identifiers

CAS NumberUN/NA NumberDOT Hazard LabelUSCG CHRIS Code
  • 74-99-7  
NIOSH Pocket GuideInternational Chem Safety Card
Methyl acetylene

NFPA 704

General Description

A colorless liquefied gas with a sweet odor. mp: -104°C, bp: -23.1°C. Insoluble in water, soluble in ethanol, chloroform and benzene. Moderately toxic by inhalation. Used as a specialty fuel. Denser than air. Vapors may ignite at distant sources of ignition and flash back.


Reactivity Alerts

  • Highly Flammable
  • Peroxidizable Compound

Air & Water Reactions


Fire Hazard

Excerpt from ERG Guide 115 [Gases - Flammable (Including Refrigerated Liquids)]:

EXTREMELY FLAMMABLE. Will be easily ignited by heat, sparks or flames. Will form explosive mixtures with air. Vapors from liquefied gas are initially heavier than air and spread along ground. CAUTION: Hydrogen (UN1049), Deuterium (UN1957), Hydrogen, refrigerated liquid (UN1966) and Methane (UN1971) are lighter than air and will rise. Hydrogen and Deuterium fires are difficult to detect since they burn with an invisible flame. Use an alternate method of detection (thermal camera, broom handle, etc.) Vapors may travel to source of ignition and flash back. Cylinders exposed to fire may vent and release flammable gas through pressure relief devices. Containers may explode when heated. Ruptured cylinders may rocket. (ERG, 2016)

Health Hazard

Exposure Routes: inhalation, skin and/or eye contact (liquid)

Symptoms: Irritation respiratory system; tremor, hyperexcitability, anesthesia; liquid: frostbite

Target Organs: respiratory system, central nervous system (NIOSH, 2016)

Reactivity Profile

1-PROPYNE is highly flammable. The liquid material in cylinders contains about 30% propadiene. Detonation may occur at 95° C [MCA Case History No. 632]. Reacts exothermically with many oxidizing agents and with some reducing agents as well. May react with silver, copper, and mercury salts in aqueous solution to give explosive acetylides. Incompatible with brass that contains more than 65% copper, with other copper-containing alloys, with Monel metal, with neoprene, polyethylene, and, to a lesser extent, with Teflon. May enflame in air in the presence of Co, Hg, Hg salts, K, Ag, Ag salts, RbH, CsH, halogens, HNO3, NaH. Can decompose explosively when compressed to 4.5 to 5.6 atmospheres. Moderate explosion hazard when exposed to heat or flame or by spontaneous chemical reaction. Has been known to decompose explosively at high pressures and moderate temperatures in the absence of air.

Belongs to the Following Reactive Group(s)

Potentially Incompatible Absorbents

Use caution: Liquids with this reactive group classification have been known to react with the absorbent listed below. More info about absorbents, including situations to watch out for...

Response Recommendations

Isolation and Evacuation

Excerpt from ERG Guide 115 [Gases - Flammable (Including Refrigerated Liquids)]:

As an immediate precautionary measure, isolate spill or leak area for at least 100 meters (330 feet) in all directions.

LARGE SPILL: Consider initial downwind evacuation for at least 800 meters (1/2 mile).

FIRE: If tank, rail car or tank truck is involved in a fire, ISOLATE for 1600 meters (1 mile) in all directions; also, consider initial evacuation for 1600 meters (1 mile) in all directions. In fires involving Liquefied Petroleum Gases (LPG) (UN1075); Butane, (UN1011); Butylene, (UN1012); Isobutylene, (UN1055); Propylene, (UN1077); Isobutane, (UN1969); and Propane, (UN1978), also refer to BLEVE - SAFETY PRECAUTIONS (ERG page 368). (ERG, 2016)


Excerpt from ERG Guide 115 [Gases - Flammable (Including Refrigerated Liquids)]:

DO NOT EXTINGUISH A LEAKING GAS FIRE UNLESS LEAK CAN BE STOPPED. CAUTION: Hydrogen (UN1049), Deuterium (UN1957) and Hydrogen, refrigerated liquid (UN1966) burn with an invisible flame. Hydrogen and Methane mixture, compressed (UN2034) may burn with an invisible flame.

SMALL FIRE: Dry chemical or CO2.

LARGE FIRE: Water spray or fog. Move containers from fire area if you can do it without risk.

FIRE INVOLVING TANKS: Fight fire from maximum distance or use unmanned hose holders or monitor nozzles. Cool containers with flooding quantities of water until well after fire is out. Do not direct water at source of leak or safety devices; icing may occur. Withdraw immediately in case of rising sound from venting safety devices or discoloration of tank. ALWAYS stay away from tanks engulfed in fire. For massive fire, use unmanned hose holders or monitor nozzles; if this is impossible, withdraw from area and let fire burn. (ERG, 2016)

Non-Fire Response

Excerpt from ERG Guide 115 [Gases - Flammable (Including Refrigerated Liquids)]:

ELIMINATE all ignition sources (no smoking, flares, sparks or flames in immediate area). All equipment used when handling the product must be grounded. Do not touch or walk through spilled material. Stop leak if you can do it without risk. If possible, turn leaking containers so that gas escapes rather than liquid. Use water spray to reduce vapors or divert vapor cloud drift. Avoid allowing water runoff to contact spilled material. Do not direct water at spill or source of leak. Prevent spreading of vapors through sewers, ventilation systems and confined areas. Isolate area until gas has dispersed. CAUTION: When in contact with refrigerated/cryogenic liquids, many materials become brittle and are likely to break without warning. (ERG, 2016)

Protective Clothing

Skin: Wear appropriate personal protective clothing to prevent skin from becoming frozen from contact with the liquid or from contact with vessels containing the liquid.

Eyes: Wear appropriate eye protection to prevent eye contact with the liquid that could result in burns or tissue damage from frostbite.

Wash skin: No recommendation is made specifying the need for washing the substance from the skin (either immediately or at the end of the work shift).

Remove: Work clothing that becomes wet should be immediately removed due to its flammability hazard(i.e. for liquids with flash point < 100°F)

Change: No recommendation is made specifying the need for the worker to change clothing after the work shift.

Provide: Quick drench facilities and/or eyewash fountains should be provided within the immediate work area for emergency use where there is any possibility of exposure to liquids that are extremely cold or rapidly evaporating. (NIOSH, 2016)

DuPont Tychem® Suit Fabrics

No information available.

First Aid

Eye: If eye tissue is frozen, seek medical attention immediately; if tissue is not frozen, immediately and thoroughly flush the eyes with large amounts of water for at least 15 minutes, occasionally lifting the lower and upper eyelids. If irritation, pain, swelling, lacrimation, or photophobia persist, get medical attention as soon as possible.

Skin: If frostbite has occurred, seek medical attention immediately; do NOT rub the affected areas or flush them with water. In order to prevent further tissue damage, do NOT attempt to remove frozen clothing from frostbitten areas. If frostbite has NOT occurred, immediately and thoroughly wash contaminated skin with soap and water.

Breathing: If a person breathes large amounts of this chemical, move the exposed person to fresh air at once. If breathing has stopped, perform mouth-to-mouth resuscitation. Keep the affected person warm and at rest. Get medical attention as soon as possible. (NIOSH, 2016)

Physical Properties

Flash Point: data unavailable

Lower Explosive Limit (LEL): 1.7 % (NIOSH, 2016)

Upper Explosive Limit (UEL): data unavailable

Autoignition Temperature: data unavailable

Melting Point: -153 ° F (NIOSH, 2016)

Vapor Pressure: 5.2 atm (NIOSH, 2016)

Vapor Density (Relative to Air): data unavailable

Specific Gravity: data unavailable

Boiling Point: -10 ° F at 760 mm Hg (NIOSH, 2016)

Molecular Weight: 40.1 (NIOSH, 2016)

Water Solubility: Insoluble (NIOSH, 2016)

Ionization Potential: 10.36 eV (NIOSH, 2016)

IDLH: 1700 ppm Based on 10% of the lower explosive limit. (NIOSH, 2016)

AEGLs (Acute Exposure Guideline Levels)

No AEGL information available.

ERPGs (Emergency Response Planning Guidelines)

No ERPG information available.

PACs (Protective Action Criteria)

Methyl acetylene (74-99-7) 230 ppm 2500 ppm 15000 ppm LEL = 17000 ppm

(DOE, 2016)

Regulatory Information

The Regulatory Information fields include information from the U.S. Environmental Protection Agency's Title III Consolidated List of Lists, the U.S. Department of Homeland Security's Chemical Facility Anti-Terrorism Standards, and the U.S. Occupational Safety and Health Administration's Process Safety Management of Highly Hazardous Chemicals Standard List (see more about these data sources).

EPA Consolidated List of Lists

Regulatory NameCAS Number/
313 Category Code
CAA 112(r)
1-Propyne74-99-710000 pounds
Propyne74-99-710000 pounds

(EPA List of Lists, 2015)

DHS Chemical Facility Anti-Terrorism Standards (CFATS)

Chemical of InterestCAS NumberMin ConcSTQSecurity
Min ConcSTQSecurity
Min ConcSTQSecurity
Propyne; [1-Propyne] 74-99-71.00 %10000 poundsflammable

(DHS, 2007)

OSHA Process Safety Management (PSM) Standard List

No regulatory information available.

Alternate Chemical Names

This section provides a listing of alternate names for this chemical, including trade names and synonyms.