Diisobutylene polymerization

Sulfuric acid finds commercial application in the polymerization of isobutylene to diisobutylene (a mixture of the two 2,4,4-trimethylpen-tenes) and the copolymerization of isobutylene with the n-butylenes to obtain a more complex mixture of octylenes. Dilute (65-70 %) acid is used at 20-35° for the polymerization of only the isobutylene. The copolymerization occurs in the so-called hot acid polymerization process in which the dilute sulfuric acid is employed at about 80-90°. If more concentrated sulfuric acid is used, particularly acid of concentration above about 90%, conjunct polymerization occurs even at —35°. 

The gas phase polymerization of diisobutylene with boron fluoride also did not occur unless a third component was present. The addition of water or acetone caused the mixture to react rapidly, the boron fluoride combining instantaneously with the vapor of the third component in approximately equimolecular quantities. Certain substances, oxygen, hydrogen sulfide, and hydrogen chloride, did not produce a rapid polymerization of diisobutylene these substances did not combine with the boron fluoride. In each of these cases, the final addition of water to the nonreacting mixture resulted in rapid polymerization. Ammonia formed an addition compound with the boron fluoride in approximately equimolecular quantities, but did not bring about the polymerization of the diisobutylene until water vapor was added, after which rapid reaction occurred (Evans and Weinberger, 85). 

To facilitate structure characterization, it was mandatory to minimize propagation. Thus a nonpolymerizable monomer was chosen, that is, an olefin which would undergo all the reactions of a polymerizable monomer (for example, isobutylene) except that it would not propagate. 2,4,4-Trimethyl-l-pentene (diisobutylene) was selected. This monomer is structurally closely related to isobutylene and due to its bulky substituents, it is unable to propagate. Model polymerization studies with this olefin could be viewed as polymerization without propagation . 

Isobutylene, CH2=C(CH3)2, is predominantly produced from cracked petroleum gases, and also, partially, by the dehydration of /-butanol. In industrial polymerizations, isobutylene is liquefied on addition of some diisobutylene, and mixed with about the same quantity of liquid ethylene and then cationically polymerized at -80°C with BF3/H2O. The diisobutylene acts as chain transfer agent and regulates the molar mass. The ethylene does not polymerize under these conditions on the other hand, it dissipates the heat of polymerization by volatilizing. 

The alkylphenol p-tert-octyl phenol (PTOP) is the product of a branched-chain, eight-carbon-containing olefins, and phenol yielding the general structure as shown in Structure 3.13. The PTOP-based surfactants are used mainly in the same applications as PNP-based surfactants. In addition, a major use is as a surfactant in the emulsion polymerization of acrylic and vinyl polymers. Consumption of PTOP-based surfactants is believed to exceed 60 million lb per year. These surfactants are considered to be more of a specialty type because of the higher raw material cost of the diisobutylene as compared to nonene. 

Table A.3 shows that EMA resins and its derivatives are also claimed to be useful in many other applications. Such uses include thickeners for other polymeric systems, shampoos, paint removers, and latex binder for nonwoven fabrics. Derivatives of the resins function well as suspending agents for fillers and powdered chemicals such as insecticides, cleaning solutions, lubricants, ceramics, and other applications. The diisobutylene-MA sodium salt material has been cleared for use as a dispensing or suspending agent for pesticide delivery systems.

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