The Ziegler process

The Ziegler process, based on reactions discovered in the 1950s, produces predorninandy linear, primary alcohols having an even number of carbon atoms. The process was commercialized by Continental Oil Company in the United States in 1962, by Condea Petrochemie in West Germany (a joint venture of Continental Oil Company and Deutsche Erdid, A.G.) in 1964, by Ethyl Corporation in the United States in 1965, and by the USSR in 1983. 

Eatty alcohols, prepared from fatty acids or via petrochemical processes, aldol or hydroformylation reactions, or the Ziegler process, react with ammonia or a primary or secondary amine in the presence of a catalyst to form amines (10—12). 

In the mid-1950s a number of new thermoplastics with some very valuable properties beeame available. High-density polyethylenes produced by the Phillips process and the Ziegler process were marketed and these were shortly followed by the discovery and rapid exploitation of polypropylene. These polyolefins soon became large tonnage thermoplastics. Somewhat more specialised materials were the acetal resins, first introduced by Du Pont, and the polycarbonates, developed simultaneously but independently in the United States and Germany. Further developments in high-impact polystyrenes led to the development of ABS polymers. 

Very high molecular weight polyethylenes (A/ in the range 1-6 X 10 ) prepared by the Ziegler process have also become available. As might be expected from consideration of Figure 3.1 these polymers cannot be processed easily in the molten state without decomposition and it is therefore often necessary to process in the rubbery phase. 

The oligomerization of the ethylene proceeds as a ligand reaction in the coordination sphere of the catalyst complex, as the following reaction scheme shows. The reaction course corresponds with the Ziegler process for ethylene polymerization. 

The Ziegler process produces linear alcohols with an even number of carbon atoms and is based on the polymerization of ethylene under catalytic conditions, generally with triethylaluminum as in the Alfol and the Ethyl processes. The distribution of alkyl chains depends on the version of the process employed but the alcohols obtained after fractionation can be equivalent to those obtained from fats and oils or have purpose-made distributions depending on the fractionation conditions. 

The basic process steps in the Ziegler process are the synthesis of the tri-ethylaluminum catalyst, chain growth from an ethylene precursor, oxidation, and finally hydrolysis. 

The mechanism of hydrosilation can be rationalized as described by Chalk and Harrod (1 l-lId). In this view, all the chemical changes take place within the coordination sphere of a transition metal. Other reactions of unsaturated molecules are explained in much the same way. Hydrogenation, the oxo-process, and the Ziegler process are important examples. 

CP [Continuous polymerization] A continuous process for making high-density polyethylene, based on the Ziegler process but using a much more active catalyst so that de-ashing (catalyst removal) is not required. Developed by Mitsui Petrochemical Industries and upgraded into its CX process, which was first licensed in 1976. 

The various steps introduced in the production of alcohols from ethylene are represented in Fig. 1.11. Similar to the production of a-olefins, in the production of alcohols using the Ziegler process, the final product is a mix showing a typical Poisson distribution with alcohols from C4 up to C2s- Alcohols are also obtained from n-paraffin... 

This process seems much simpler than the Ziegler process, and you may wonder why it has not crowded Ziegler out. The problem is the olefin feed. Where do you get a ready supply of olefins the right size to feed to the process The answer is you have to malce them, and therein lies the rub. Normal paraffins from petroleum waxes or other chemical processes provide the feedstock to a two-step process, chlorination and dehydrochlorination, which produces an olefin corresponding to the paraffin. 

Another source, catalytic oligomerization, which produces the alpha olefins using the Ziegler process mentioned above, has its own treatment in Chapter 21. But then the Oxo process really only replaces steps-three and four in Figure 15-3. Besides, Oxo higher alcohols still have branches. 

In 25 words or less, describe the differences between the Oxo process and the Ziegler process for making higher alcohols. 

The Ziegler process based on a triethyl aluminum catalyst... 

What is the difference between the Ziegler process for producing alpha olefins and the one described in Chapter 15 for producing higher alcohols ... 

In the Ziegler process, why do you think there is a distribution of different carbon count alpha olefins rather than just one ... 

What is the main difference in results between the Ziegler process and the Alpha Select process ... 

In the higher alcohol process, the displacement is affected by oxidizing the trialkyl aluminum and then hydrolyzing, to form aluminum hydroxide and the linear alcohol. In the Ziegler process for alpha olefins, ethylene is used to displace the alpha olefin. 

The Ziegler process produces the full range of alpha olefins, from C4 to C2o The Alpha Select process produces C4 through Cio-... 

Polymerization of propene by the Ziegler process gives a very useful plastic material. It can be made into durable fibers or molded into a variety of shapes. Copolymers (polymers with more than one kind of monomer unit in the polymer chains) of ethene and propene made by the Ziegler process have highly desirable rubberlike properties and are potentially the cheapest useful elastomers... 

Recycled HDPE items (blow-moulding grade) produced from HDPE made by the Phillips process were analysed by IR spectroscopy. The absorption bands at 888 and 965 cm-1, corresponding to unsaturations of vinylidene and vinylene type, respectively, are common in PE produced by either the Ziegler process or metallocenes [104]. The absence of these bands in the IR spectrum of the different samples confirmed that the resins had been produced using a Cr-type catalyst [118]. 

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