1-hexene

From Freepedia

1-hexene is a higher olefin, or alkene, with a formula C6H12. 1-hexene is an alpha-olefin, meaning that the double bond is located at the alpha (primary) position, endowing this compound with higher reactivity and thus useful chemical properties.

CAS RN:                   592-41-6  
Density:                  0.673  
Refractive index:         1.3879  
Flashpoint (C):           -26  
DOT #:                    UN 2370  
State at STP*:            liquid  
Molecular weight:         84.1608  
Melting point (C):        -139.8  
Boiling point (C):        63  
Vapor density:            3  
Vapor pressure @ 60F:     2.6 psia  
Water solubility:         insoluble  
Critical temperature(F):  447.40 F
Critical pressure (psia): 458
Critical density (g/ml):  0.241

Synthesis

Industrially, 1-hexene is commonly manufactured by two main routes: oligomerization of ethylene and by Fischer-Tropsch synthesis followed by purification. Another route to 1-hexene which has been used commercially on small scale is dehydration of alcohols. Prior to about 1970's 1-hexene was also manufactured by thermal cracking of waxes, whereas linear internal hexenes were also manufactured by chlorination/dehydrochlorination of linear paraffins.

There are five commercial processes which oligomerize ethylene to 1-hexene. Four of these processes produce 1-hexene as a part of a wide distribution of alpha-olefins. Typically, 1-hexene content of the entire distribution of alpha-olefins ranges from about 20% of the distribution in Ethyl (Innovene) process to about 12% of distribution in some modes of Gulf (CP Chemicals) and Idemitsu process. One process, Phillips ethylene trimerization process, produces only 1-hexene.

The only commercial process to isolate 1-hexene from a wide mixture of C6 hydrocarbons is practiced by Sasol Ltd., a South African oil and gas and petrochemical company. Sasol commercially employs Fischer-Tropsch synthesis ot make fuels and recovers 1-hexene from these fuel streams, where the initial 1-hexene concentration in a narrow distillation cut may be 60%, with the remainder being vinylidenes, linear and branched internal olefins, linear and branched paraffins, alcohols, aldehydes, carboxylic acids and aromatic compounds.

Applications

The primary, even overwhelming, use of 1-hexene is as a comonomer in production of polyethylene. High Density PolyEthylene (HDPE) and Linear Low Density PolyEthylene (LLDPE) use approximately 2-4% and 8-10% of comonomers, respectively.

Another significant use of 1-hexene is for production linear alcohols via OXO Synthesis (hydroformulation) for later production of linear plasticizers.