Propylene rearrangement

If desired, the alcohol may be identified as the 3 5-dinitrobenzoate (Section 111,27) it is then best to repeat the experiment on a larger scale and to replace the dilute hydrochloric acid by dilute sulphuric acid. It must, however, be pointed out that the reaction is not always so simple as indicated in the above equation. Olefine formation and rearrangement of the alcohol sometimes occur thus n-prop3 lamine yields n-propyl alcohol, isopropyl alcohol and propylene. 

Propylene oxide-based glycerol can be produced by rearrangement of propylene oxide [75-56-9] (qv) to allyl alcohol over triUthium phosphate catalyst at 200—250°C (yield 80—85%) (4), followed by any of the appropriate steps shown in Figure 1. The specific route commercially employed is peracetic acid epoxidation of allyl alcohol to glycidol followed by hydrolysis to glycerol (5). The newest international synthesis plants employ this basic scheme. 

Polyether Polyols. Polyether polyols are addition products derived from cyclic ethers (Table 4). The alkylene oxide polymerisation is usually initiated by alkah hydroxides, especially potassium hydroxide. In the base-catalysed polymerisation of propylene oxide, some rearrangement occurs to give aHyl alcohol. Further reaction of aHyl alcohol with propylene oxide produces a monofunctional alcohol. Therefore, polyether polyols derived from propylene oxide are not truly diftmctional. By using sine hexacyano cobaltate as catalyst, a more diftmctional polyol is obtained (20). Olin has introduced the diftmctional polyether polyols under the trade name POLY-L. Trichlorobutylene oxide-derived polyether polyols are useful as reactive fire retardants. Poly(tetramethylene glycol) (PTMG) is produced in the acid-catalysed homopolymerisation of tetrahydrofuran. Copolymers derived from tetrahydrofuran and ethylene oxide are also produced. 

As propylene oxide is introduced into the reactor, a portion of it is converted to allyl alcohol and propenyl alcohol via a rearrangement [5] ... 

The mechanism of the polymerization contains ionic intermediate steps. The free H+ goes to a carbenium ion and, as shown in route B, rearranges to form tetrapropylene. It is highly likely that this actual tetrapropylene exists only in very small concentrations. The product variety is explained by the rearrangement of the carbenium ion to dodecene isomers according to route C. In addition, short-chain olefins formed by fragmentation (route D). Polymerization proceeds at almost 100% to mono olefins. Aromatics, paraffins, and diolefins exist only in trace amounts. The propylene tetramer is best characterized by its distillation range. 

A complex such as Ta(CHCMe3)(PMe3)2Cl3 reacts readily with ethylene, propylene, or styrene to give all of the possible products (up to four) which can be formed by rearrangement of Intermediate metallacyclobutane complexes (two for substituted olefins) by a p-hydride elimination process (e.g., equation 2) ( ). We saw... 

It is difficult to explain the rearrangement except by the indicated reaction steps. If these steps do occur, the propylene and HCo(CO)4 must be rather tightly complexed otherwise part or all of the volatile olefin would be lost. 

Surface Acidity of Solid Catalysts H. a. Benesi and B. H. C. Winquist Selective Oxidation of Propylene George W. Keulks, L. David Krenzke, AND Thomas N. Notermann a-n Rearrangements and Their Role in Catalysis... 

The MNDO method has been employed " to study the acid-catalysed rearrangement of propylene 1,2-glycol. Propanaldehyde was found to be the major product with a small amount of acetone also being produced. The solid-state pinacol rearrangement of l,l,2-triphenylethane-l,2-diol has been performed over various solid... 

McLafferty rearrangements miz 164 (loss of ethylene), 150 (loss of propylene), and a double-McLafferty loss to 122. Compound 490 exhibits two major fragments at mIz 100 and 98 in accordance with the fragmentation of piperazines. An assumed structure was confirmed by synthesis 464). 

Anastopoulos et al. [47] have analyzed interfacial rearrangements of triphenyl-bismuth and triphenylantimony at mercury electrode in nonaqueous solvents of high dielectric constant. These phenomena were detected as the peaks in the capacitance-potential curves at intermediate negative potentials for triphenyl-bismuth and triphenylantimony in N-methylformamide, A,A-dimethylforma-mide, dimethyl sulfoxide, propylene carbonate, and methanol solutions. 

The most common current method of phenol production is from the cumene hydroperoxide rearrangement process. In this process, benzene reacts with propylene to produce cumene. Cumene is oxidized to cumene hydroperoxide. When cumene hydroperoxide is treated with dilute sulfuric acid, it rearranges and splits into phenol and acetone. Because the reactants are inexpensive and the process is simple, the acidic oxidation of cumene is used to produce more than 95% of the worlds supply of phenol. 

When the commodity chemical propylene oxide is heated to high temperature in the gas phase in a shock tube, unimolecular rearrangement reactions occur that generate the CsHgO isomers allyl alcohol, methyl vinyl edier, propanal, and acetone (Figure 15.9). Dubnikova and Lifshitz carried out a series of calculations to determine the mechanistic pathway(s) for each isomerization, with comparison of activation parameters to those determined from Arrhenius fits to experimental rate data to validate the theoretical protocol. 

Formed carbocations can undergo p scission [Eq. (2.8)] to yield propylene (or the corresponding alkene, but not ethylene) and a new primary cation. The primary ion rapidly rearranges to a secondary ion involving a hydride shift [Eq. (2.9)], which, in turn, can continue the process. Isomeric cations may also be formed through intermediate alkenes [Eq. (2.10)] ... 

Oxidation of the allylic carbon of alkenes may lead to allylic alcohols and derivatives or a, 3-unsaturated carbonyl compounds. Selenium dioxide is the reagent of choice to carry out the former transformation. In the latter process, which is more difficult to accomplish, Cr(VI) compounds are usually applied. In certain cases, mixture of products of both types of oxidation, as well as isomeric compounds resulting from allylic rearrangement, may be formed. Oxidation of 2-alkenes to the corresponding cc,p-unsaturated carboxylic acids, particularly the oxidation of propylene to acrolein and acrylic acid, as well as ammoxidation to acrylonitrile, has commercial importance (see Sections 9.5.2 and 9.5.3). 

The rate constants at several different temperatures are obtained for the rearrangement of cyclopropane (A) to propylene (B) ... 

Catalysis. The isomerization of cyclopropane to propylene and the rearrangement of protoadamantane to adamantane were studied on HY zeolite and samples of materials A and B. 

Minachev, Eidus et al. (25) found that Ca, Ni, Co, and NdY zeolites were active in the disproportionation of propylene to ethylene and butenes. The process was accompanied by hydrogen rearrangement to form saturated hydrocarbons and condensation products. The selectivity in this reaction depends on the composition of the catalysts, their pretreatment, and the experimental conditions (26). 

Under ordinary conditions, this may not be a major reaction, but for the problem of acetylene formation it is notable that Cvetanovic and Callear (19), and Mitchell and Le Roy (49), in studies of the photosensitized decomposition of ethylene, found a uni-molecular mechanism. Ingold and Stubbs (33) also found that the decomposition of propylene starts with a molecular rearrangement and decomposition ... 

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