Propyne

  • Allylene
  • Methyl acetylene
Formula
C3H4
Structure
Description
Colorless gas with a sweetish odor.
Uses
Welding torch fuel, chemical synthesis.

Registry Numbers and Inventories.
CAS
74-99-7
EC (EINECS/ELINCS)
200-828-4
S 9 16 23 33
RTECS
UK4250000
RTECS class
Mutagen
UN (DOT)
1954
Beilstein/Gmelin
878138
Beilstein Reference
4-01-00-00958
Swiss Giftliste 1
G-1063
Canada DSL/NDSL
DSL
US TSCA
Listed
Austrailia AICS
Listed
New Zealand
Listed
Japan ENCS (MITI)
Listed
Korea ECL
Listed

Properties.
Formula
C3H4
Formula mass
40.07
Melting point, °C
-102.7
Boiling point, °C
-23.2
Vapor pressure, mmHg
3876 (20 C)
Vapor density (air=1)
1.4
Critical temperature
128.7
Critical pressure
52.8
Density
0.6447 g/cm3 (-1 C)
Solubility in water
3.64 g/L
Viscosity
8.4x10-3 MPa-s (25 C)
Surface tension
22.61 g/s2 (-37 C)
Refractive index
1.3863 (-40 C)
Partition coefficient, pKow
0.94
Heat of vaporization
23.29 kJ/mol
Heat of combustion
-1958 kJ/mol

Hazards and Protection.
Storage
Outside storage in cool, well-ventilated area is advised.
A B1
Handling
Store and handle in accordance with all current regulations and standards. Subject to storage regulations: U.S. OSHA 29 CFR 1910.101. Keep separated from incompatible substances.
Protection
Wear appropriate clothing to prevent any reasonable probability of skin contact. Wear eye protection to prevent any possibility of eye contact.
Respirators
Any self-contained breathing apparatus that has a full facepiece and is operated in a pressure-demand or other positive pressure mode. Any supplied-air respirator with a full face piece and operated in pressure-demand or other positive pressure mode in combination with an auxiliary self-contained breathing apparatus operated in pressure-demand or other positive pressure mode. Any appropriate escape-type, self-contained breathing apparatus.
Small spills/leaks
Make no contact with the spilled material. ELIMINATE all ignition sources, combustibles and ground all equipment. Take up with sand or other noncombustible absorbent material and place into containers for later disposal.
Stability
Unstable.
Incompatibilities
React vigorously with strong oxidizing materials, reaction with silver nitrate forms acetylide igniting at 150 C.
Decomposition
Can decompose explosively at 4.5 To 5.6 atmospheres of pressure.

Fire.
Flash Point,°C
-87
Upper exp. limit, %
12.5
Lower exp. limit, %
1.7
Fire fighting
Stop flow of gas
Fire potential
Dangerous, when exposed to heat or flame induced decomposition of the endothermic hydrocarbon leads to flame propagation in absence of air above minimum pressures of 3. 4 And 2. 1 Bar at 20 and 120 C, respectively.
Hazards
Vapors from liquefied gas are initially heavier than air and spread along ground. Vapors may travel to source of ignition and flash back. Containers may explode when heated.
Combustion products
Toxic gases and vapors (such as carbon monoxide) may be released in a fire involving methyl acetylene.
Health
1
 
Flammability
4
 
 
Reactivity
3
 

Health.
Exposure limit(s)
TLV: 1000 ppm; 1640 mg/m3 (ACGIH 1996). OSHA PEL: TWA 1000 ppm (1650 mg/m3) NIOSH REL: TWA 1000 ppm (1650 mg/m3) NIOSH IDLH: 1700 ppm LEL
Poison_Class
5
Exposure effects
Rapid breathing and rapid heart rate are common. In severe cases abnormally low blood pressure, apnea, and cardiac arrest develop. Various disturbances including headache, dizziness, mood disturbances, numbness of the extremities, sleepiness, mental confusion, poor judgement and coordination, and memory loss may occur. Prolonged or severe hypoxia results in unconsciousness. Prolonged asphyxia may produce CNS injury. Hemiparesis has been reported with volatile substance abuse. Cerebral edema with brainstem herniation may occur. Seizures have been reported following intentional inhalation.
   Ingestion
Nausea, vomiting, and gastrointestinal hemorrhage may develop.
   Inhalation
Hyperventilation may develop.
   Skin
Dermal exposure may cause frostbite injury. Severe tissue burns have been reported.
   Eyes
Decreases in night vision, visual acuity, and visual fields (tunnel vision) may occur. Frothy mucous may be seen.

First aid
 
   Ingestion
Seek medical assistance.
   Inhalation
Administer 100% humidified supplemental oxygen with assisted ventilation as required. If hypoxia has been severe or prolonged, carefully evaluate for neurologic sequelae and provide supportive treatment as indicated. Pulmonary edema (noncardiogenic): maintain ventilation and oxygenation and evaluate with frequent arterial blood gas or pulse oximetry monitoring. E
   Skin
Rewarming and a variety of topical treatments are indicated for frostbite injury. See main section for more information.
   Eyes
Irrigate exposed eyes with copious amounts of tepid water for at least 15 minutes. If irritation, pain, swelling, lacrimation, or photophobia persist, the patient should be seen in a health care facility.

Transport.
UN number
1954
Response guide
Hazard class
2.1
USCG CHRIS Code
MCE