LINEAR ALCOHOLS

Linear alcohols (C_l2-C₂₆) are important chemicals for producing various compounds such as plasticizers, detergents, and solvents. They are also produced by the oligomerization of ethylene using aluminum alkyls (Ziegler catalysts). The Alfol process (Figure 1.1) for producing linear primary alcohols is a four-step process. In the first step, triethylaluminum is produced by the reaction of ethylene with hydrogen and aluminum metal:

In the next step, ethylene is polymerized by the action of triethylaluminum at approximately 120°C and 130 atmospheres to trialkylaluminum. Typical reaction time is approximately 140 minutes for an average C₁₂ alcohol production:

Figure 1.1. The Alfol process for making even-numbered straight-chain alpha alcohols.

The oxidation of triethylaluminum is carried out between 20–50°C with “bone dry” air to aluminum trialkoxides.

The final step is the hydrolysis of the trialkoxides with water to the corresponding even-numbered primary alcohols. Alumina is coproduced and is characterized by its high activity and purity:

Linear alcohols in the range of C_l0–C_l2 are used to make plasticizers. Those in the range of C_l2–C_l6 are used for making biodegradable detergents.

They are either sulfated to linear alkylsulfates (ionic detergents) or reacted with ethylene oxide to the ethoxylated linear alcohols (nonionic detergents). The C_l6–C_l8 alcohols are modifiers for wash and wear polymers. The higher alcohols, C₂₀–C₂₆, are synthetic lubricants and mold release agents.