Propylene allyl acetate from

FIGURE 1 Manufacture of allyl alcohol (via allyl acetate) from propylene and acetic acid. 

Like vinyl acetate from ethylene, allyl acetate is produced by the vapor-phase oxyacylation of propylene. The catalyzed reaction occurs at approximately 180°C and 4 atmospheres over a Pd/KOAc catalyst ... 

The production of 1,4-butanediol (1,4-BDO) from propylene via the carbonylation of allyl acetate is noted in Chapter 8. 1,4-Butanediol from maleic anhydride is discussed later in this chapter. An alternative route for the diol is through the acetoxylation of butadiene with acetic acid followed by hydrogenation and hydrolysis. 

Heterogeneous palladium catalysts proved to be active in the conversion of simple alkenes to the corresponding allylic acetates, carbonyl compounds, and carboxylic acids.694 704 Allyl acetate or acrylic acid from propylene was selectively produced on a palladium on charcoal catalyst depending on catalyst pretreatment and reaction conditions.694 Allylic oxidation with singlet oxygen to yield allylic hydroperoxides is discussed in Section 9.2.2. 

The in situ regeneration of Pd(II) from Pd(0) should not be counted as being an easy process, and the appropriate solvents, reaction conditions, and oxidants should be selected to carry out smooth catalytic reactions. In many cases, an efficient catalytic cycle is not easy to achieve, and stoichiometric reactions are tolerable only for the synthesis of rather expensive organic compounds in limited quantities. This is a serious limitation of synthetic applications of oxidation reactions involving Pd(II). However it should be pointed out that some Pd(II)-promoted reactions have been developed as commercial processes, in which supported Pd catalysts are used. For example, vinyl acetate, allyl acetate and 1,4-diacetoxy-2-butene are commercially produced by oxidative acetoxylation of ethylene, propylene and butadiene in gas or liquid phases using Pd supported on silica. It is likely that Pd(OAc)2 is generated on the surface of the catalyst by the oxidation of Pd with AcOH and 02, and reacts with alkenes. 

In the first step of the process (Fig. 1), the acetoxylation of propylene is carried out in the gas phase, using solid catalyst containing palladium as the main catalyst at 160 to 180°C and 70 to 140 psi (0.49 to 0.98 MPa). The reactor effluents from the reactor are separated into liquid components and gas components. The liquid components containing allyl acetate are sent to the hydrolysis process. The gas components contain unreacted gases and... 

From previously reported studies then, several different products are possible. The initial attack by the oxygen moiety may apparently be vinylic (on either of the two carbons of the double bond) or allylic (on the carbon next to the doubly bonded carbons). Distinction must be made between allylic attack as described here and allylic products which can arise either by true allylic attack or by vinylic attack followed by olefinic isomerization. Thus it is not clear whether such products as 2-hexen-l-yl acetate(II) (58) have been formed by vinylic attack upon hexene followed by olefinic isomerization, by olefin isomerization of hexene to 2-hexene followed by allylic attack, or by some type of synchronous mechanism in which oxygen attack and olefin isomerization occur simultaneously. This last possibility could be visualized as involving some type of 7r-allylic complex (Reaction 2). This involvement of TT-allylic complex can be ruled out only in the production of isopropenyl acetate from propylene since a mechanism such as this followed by olefin isomerization could not be used in that case. For the butenes and higher... 

There are also examples of gas-phase oxidation of allyl alcohol using Pd-Cu or Pd-Ag catalysts (Eq. (8.15)) [48]. The protocol was part of a multistep propylene-oxidation process, and the allyl alcohol starting material was produced from Pd-catalyzed acetoxylation of propylene followed by hydrolysis of allyl acetate (cf. Eqs. (8.2) and (8.3)) [48]. The presence of water improves the conversion of alcohol to acrylic products. 

From higher alkenes, three kinds of products, namely alkenyl acetates, allylic acetates and dioxygenated products, are obtained. Reaction of propylene gives two propenyl acetates 77 and 78 and allyl acetate (79) by acetoxypalladation to form two intermediates 75 and 76, followed by elimination of different jS-hydrogens. 

These alternate mechanisms are exemplified by the oxidation of propylene in acetic acid. With lithium perchlorate as the supporting electrolyte, direct electron transfer from the alkene occurs to form an allylic carbenium ion, e.g., mechanism (b) above. However, in the presence of lithium nitrate, oxidation of the nitrate ion has been shown to occur preferentially and the resulting nitrate radical, NO 3, reacts with the alkene, i.e., mechanism (c). 

Allylic alcohol (2-propen-l-ol) is by far the most technically relevant unsaturated alcohol. The compound can be produced by different routes that aU use propene as the starting point. However, direct production from propene is not possible. The viable alternatives include (i) hydroxylation of allyl chloride, (ii) selective hydrogenation of acrolein, (hi) ester hydrolysis of allyl acetate, and (iv) selective ring opening of propylene oxide. 

Co-adsorption experiments show a complex role of the nature and concentration of chemisorbed ammonia species. Ammonia is not only one of the reactants for the synthesis of acrylonitrile, but also reaction with Br()>nsted sites inhibits their reactivity. In particular, IR experiments show that two pathways of reaction are possible from chemisorbed propylene (i) to acetone via isopropoxylate intermediate or (ii) to acrolein via allyl alcoholate intermediate. The first reaction occurs preferentially at lower temperatures and in the presence of hydroxyl groups. When their reactivity is blocked by the faster reaction with ammonia, the second pathway of reaction becomes preferential. The first pathway of reaction is responsible for a degradative pathway, because acetone further transform to an acetate species with carbon chain breakage. Ammonia as NH4 reacts faster with acrylate species (formed by transformation of the acrolein intermediate) to give an acrylamide intermediate. At higher temperatures the amide may be transformed to acrylonitrile, but when Brreform ammonia and free, weakly bonded, acrylic acid. The latter easily decarboxylate forming carbon oxides. 

Commerciol Dichlorohydrin consists of the above two isomers, the proportions of which depend on method of prepn d 1.36-1.39, bp 175-80°, flash p 74°, Glycerol was the main source for the prepn of glycerol chloro-hydrins until the process for direct substitutive chlorination of propylene to allyl chloride paved the way for synthesis by chlorohydrination of allyl chloride. In the synthesis from glycerol, excess HCI is used in the presence of 4% acetic acid. The reaction is run at 130° to yield 90% of product which is mainly the a,y-form. Synthesis from propylene yields a mixt of approx 70% a,/8-form 8c 30% a,y-form. Addn of HCI to epichlorohydrin, CH2 CHCH> Cl, at... 

Although they lack commercial importance, many other poly(vinyl acetal)s have been synthesized. These include acetals made from vinyl acetate copolymerized with ethylene (43—46), propylene (47), isobutylene (47), acrylonitrile (48), acrolein (49), acrylates (50,47), allyl ether (51), divinyl ether (52), maleates (53,54), vinyl chloride (55), diallyl phthalate (56), and starch (graft copolymer) (47). 

Propylene, a substrate with , /2 for oxidation at considerably higher potential than nitrate ion, gave the products indicated below eqn (68) on anodic oxidation in acetic acid containing a perchlorate or nitrate salt (Formaro et al., 1973). Both nitrates were postulated as originating from nitrate radical attack upon either an allylic hydrogen or the terminal carbon of the double bond. 

Ethylene is more rapidly oxidized than propylene. Furthermore, the substituted ethylenes do not display the dependency on reactivity of allyl C—H bonds shown over bismuth molybdate (Tables XI and XII). It is clear that the C02-producing reaction is favored by unsaturation, but not by allyl hydrogens. In fact, over Pt ter<-butylethylene, without any allyl hydrogen, was oxidized about as fast as the methylethylenes. Dienes and acids were found to inhibit the oxidation of olefins over the metals. Acetone, like acetic acid from ethylene over Pd, is considered a side reaction product rather than an intermediate. The only selective oxidation observed was an oxidative dehydrogenation of cyclohexene to benzene over Pd at —20 to +30° here no CO2 was produced. 

Acetonitrile is ically a by-product of the large-scale production of acrylonitrile (from ammonia and propylene) and contains a wide range of very low-level impurities [884] these include acrylonitrile, allyl alcohol, acrylic acid, and acetic acid. Because of the widespread use of acetonitrile in many synthetic and... 

Valuable products are produced from the oxidation of both ethylene and propylene (Figs. 1 and 2). Ethylene is epoxidized with oxygen in the vapor phase over a silver catalyst, and propylene is epoxidized with an alkyl hydroperoxide in the liquid phase using a molybdeniim catalyst system. Vinylic oxidation products or their stable isomers, including acetaldehyde, acetone, and vinyl acetate, have been manufactured by a series of related catalytic reactions. These reactions occur either in solutions of palladium complexes or on the surfaces of supported palladium catalysts. Bismuth molybdate is an effective catalyst for allylic oxidations of propylene, which are of paramount importance to the chemical industry. Propylene is oxidized in the vapor phase to give acrolein for acrylic acid manufacture or, in the presence of ammonia, to give acrylonitrile. Second- and third-generation catalysts,... 

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