Of crotyl alcohol

From the results of this kinetic study and from the values of the adsorption coefficients listed in Table IX, it can be judged that both reactions of crotonaldehyde as well as the reaction of butyraldehyde proceed on identical sites of the catalytic surface. The hydrogenation of crotyl alcohol and its isomerization, which follow different kinetics, most likely proceed on other sites of the surface. From the form of the integral experimental dependences in Fig. 9 it may be assumed, for similar reasons as in the hy-drodemethylation of xylenes (p. 31) or in the hydrogenation of phenol, that the adsorption or desorption of the reaction components are most likely faster processes than surface reactions. 

From the study of the influencing of single reactions by products and by other added substances and from the analysis of mutual influencing of reactions in coupled systems, the following conclusions can be drawn concerning adsorption of the reaction components. (1) With the exception of crotyl alcohol on the platinum-iron-silica gel catalyst, all the substances present in the coupled system, i.e. reactants, intermediate products, and final products, always adsorbed on the same sites of the catalytic surface (competitive adsorption). This nonspecificity was established also in our other studies (see Section IV.F.2) and was stated also by, for example, Smith and Prater (32), (2) The adsorption of starting reactants and the desorption of the intermediate and final products appeared in our studies always as faster, relative to the rate of chemical transformations of adsorbed substances on the surface of the catalyst. 

Ki adsorption coefficient in the monomolecular isomerization of crotyl alcohol... 

Between these two extremes of spontaneous rearrangement and total failure to rearrange, Braverman and Stabinsky36-38 have observed intermediate behavior. The reaction of crotyl alcohol with C13CSC1 afforded an equilibrium mixture of both crotyl trichlormethanesulfenate (13) and a-methylallyl trichloromethyl sulfoxide (14, equation 9). 

A major improvement in the selectivity towards crotyl alcohol by the hydrogenation of crotonaldehyde has been attained by Margitfalvi et al. [91] through the modificahon of Pt/Si02 by Sn addition via SnEfi, which was then reduced at 573 K. For Sn/Pb = 1.2, both the overall activity of the catalyst and its selectivity towards the formahon of crotyl alcohol were strongly increased. On this bimetallic catalyst, the selechvity of the formation of crotyl alcohol was over 70%. 

The magnesium ion-mediated reaction of crotyl alcohol leads to the exclusive formation of the exo-isomer of the isoxazolidine-5-methanol cycloadduct, showing regioselectivity opposite to that found in the uncatalyzed reaction (Scheme 11.47). 

Bailie et al. were the first to mention alcohol formation from aldehydes by supported gold-catalyzed selective hydrogenation. The reaction of the formation of crotyl alcohol from crotonaldehyde showed high selectivity (up to 81%) at conversions of 5-10%, with preferential hydrogenation of C=0 rather than the C=C bond [216]. The addition of thiophene promoted this selective hydrogenation. This promotional effect was also observed in similar situations for Cu and Ag, but it was not very common for gold. 

To generate the catalytically active species, the diene ligand of 18 was removed by hydrogenation with 1 atm H2 to afford the bis-aquo species (PMc3)2Rh(H2O)2 (23). In the absence of 1, addition of small allyl alcohols quickly yielded the isomerized product. However, the reaction did not tolerate terminal substitution, and isomerization of crotyl alcohol was not observed (Table 7.4). Significantly, when both crotyl alcohol and allyl alcohol were added to 23, neither substrate underwent isomerization, suggesting that crotyl alcohol inhibits the reaction. 

The oxidation of benzoin with cerium(IV) in perchloric acid solution is proposed to involve an interaction between Ce4+(aq.) ions and the keto alcohol, resulting in the formation of free radicals. The final product is benzoic acid.66 The rate of oxidation of crotyl alcohol with cerium(IV) is independent of the concentration of Ce(IV). The reaction induced polymerization of acrylonitrile indicating the formation of free radicals. The kinetics and activation parameters for the reaction have been determined.67 For the Ir(III)-catalysed oxidation of methyl ketones68 and cyclic ketones69 with Ce(IV) perchlorate, successive formation of complex between the reductant and Ce(IV) and then with the catalyst has been proposed. Results showed that in acidic solutions, iridium(III) is a more efficient catalyst than osmium and ruthenium compounds. 

Other silane byproducts than triethylsilanol or ether formation from two molecules of crotyl alcohol are not observed. Side reaction which decreases the yield of 8 may be the reduction of aldehyde 7 to the corresponding alcohol 27, if water instead of the crotyl alcohol attacks the activated aldehyde 23. 

Butenyl carbamates, CH,CH=CHCH20C0NR, (1). The (E)-2-butenyl carbamate is prepared by reaction of crotyl alcohol with N,N-diisopropylcarbamoyl chloride. The (Z)-isomer is obtained by hydrogenation of the 2-butynyl carbamate. 

The reaction is most useful for the preparation of olefinic, halo, and nitro alcohols from the corresponding substituted aldehydes and ketones. These substituents ate very often affected by other reduction procedures. Excellent directions are found in the preparations of crotyl alcohol (60%), l-bromo-5-hexanol (64%), l-chloco-4-pentanol (76%), /S,/S,/S-trichloroethyl alcohol (84%), methyl-p-chlorophenylcarbinol (81%), and o-nitrobenzyl alcohol (90%). The reaction has also been used in the preparation of certain tetralols and decalols as well as 9-fluo-renylcarbinol (50%). The thiophene and furan nuclei are not reduced. 

From results such as those in Fig. 2.8, the influence of alloy structure, hydrogen pressure, and temperature on activity and selectivity toward the formation of crotyl alcohol (2-butenol, CH3CH = CHCHpH) was determined. Both Sn/Pt(lll) alloys had similar activity and selectivity. The hydrogenation activity was about two times higher for the alloys compared to Pt(lll), but little change in selectivity was observed, and butyraldehyde (n-butanal, CH3CH2CH2CHO) was the main product... 

Yield of crotyl alcohol Selectivity Yield of cinnamyl alcohol Selectivity Yield of furfuryl alcohol Selectivity... 

Shape Selective Epoxidation of Crotyl Alcohol with HjOj in the Presence of TS-1... 

Although TS-1 has been investigated for the epoxidation of a range of molecules, e.g. butene, pentene, hexene, allyl chloride and allyl alcohol, little attention has been given to the effect of shape selectivity in the MFI zeotype framework in these reaetions. In this paper we address this aspect and exemplify the shape. selective epoxidation using a range of allylic alcohols. In particular, the shape selective epoxidation of crotyl alcohol is compared and contrasted with the reaction of allyl alcohol in a range of solvents. 

Figure 3 Product selectivity as a function of time for the reaction of crotyl alcohol (cis/trans ratio = 4.45) in methanol solvent at 30 °C.

Figure 7. Oxidation of crotyl alcohol in water at 30 °C conversion oxirane selectivity triol selectivity.

Figure 9. Oxidation of crotyl alcohol in ethanol at 30 C conversion oxirane selectivity A ether diols triol selectivity.

A few more vinyl halides can be made stereospecifically by halogenation and base-catalysed elimination. One example is the vinyl bromide E-28 available by stereospecific lruns bromination of crotyl alcohol 26 followed by stereospecific elimination.4 Various regioselectivities are available in the elimination reaction so the formation of that particular alkene is in a way more surprising than the stereopecificity of the reaction. Presumably the bromine atoms increase the acidity of nearby Hs (H-2 and H-3 in anti-21) so that one or other of the vinyl bromides will be formed. One explanation is an intramolecular elimination through an anti-peri-pimsa transition state in a chair like conformation using OLi as an internal base 26. It can reach H-3 in a five-membered cyclic array. 

XcA= conversion of crotonaldehyde, S = selectivities of crotyl alcohol (CyOH), n-butyraldehyde (BA), n-buta-nol (BuOH), ethyl methyl ketone (EMK), other products (OP = hydrocarbons, allylcarbinol, 2-butanol, 2-ethyl-hexanal) rcA = catalyst activity [10 /mol g g h ]... 

As is all too commonly the case in fine chemical synthesis, the industrially required product is the a,/ -unsaturated alcohol, these being of major use as intermediates in the formation of perfumes, flavourings and pharmaceuticals.10 As expected Cu and Ni yield only butyraldehyde and butanol, although surprisingly a Cu-Ni alloy results in a selectivity of 54% crotyl alcohol.11 Platinum alone yields butyraldehyde selectively at 433 K, but the addition of iron results in the formation of crotyl alcohol.12,13 The use of liquid phase reactors has a significant effect on the selectivities observed in the reaction. For example, high selectivities to crotyl alcohol are observed for Ru, Re and Os on several supports, with Os/ZnO giving a reported selectivity of 97%.14 However, certainly in the case of Ru... 

The kinetic analysis provides a fascinating insight into the detailed reaction mechanism. The rates of formation and removal of butyraldehyde are reduced by the presence of sulphur, but more surprisingly the rate of crotyl alcohol hydrogenation to butanol is increased. Hence the enhanced selectivity to crotyl alcohol exhibited by the sulphur modified catalysts can... 

Application of a regression program to experimental data shows (Fig.6), that eq. (3) can adequately describe dependence of crotyl alcohol mole fraction as a function of crotonaldehyde mole fraction. The object function (sum of squares) was 0.00011 with the following values of parameters Lc =0.22510.013, Mc= 0.23010.03. 

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