Of crotonaldehyde

Normal butyl alcohol, propyl carbinol, n-butanol, 1-buianol, CH3CH2CH2CH2OH. B.p. 117 C. Manufactured by reduction of crotonaldehyde (2-buienal) with H2 and a metallic catalyst. Forms esters with acids and is oxidized first to butanal and then to butanoic acid. U.S. production 1978 300 000 tonnes. 

The reaction is readily illustrated by the formation of crystalline sorbic acid by the condensation of crotonaldehyde and malonic acid in hot pyridine solution ... 

Add 4 g. of malonic acid to 4 ml. of pyridine, and then add 3 1 ml. of crotonaldehyde. Boil the mixture gently under reflux over an asbestos-covered gauze, using a small Bunsen flame, for 40 minutes and then cool it in ice-water. Meanwhile add 2 ml. of concentrated sulphuric acid carefully with shaking to 4 ml. of water, cool the diluted acid, and add it with shaking to the chilled reaction-mixture. Sorbic acid readily crystallises from the solution. Filter the sorbic acid at the pump, wash it with a small quantity of cold water and then recrystallise it from water (ca, 25 ml.). The colourless crystals, m.p. 132-133°, weigh ro-i-2 g. 

The commercial method consists in the oxidation of crotonaldehyde, which is itself prepared from acetaldehyde (see Section 111,141) ... 

The synthesis of spiro compounds from ketones and methoxyethynyl propenyl ketone exemplifies some regioselectivities of the Michael addition. The electrophilic triple bond is attacked first, next comes the 1-propenyl group. The conjugated keto group is usually least reactive. The ethynyl starting material has been obtained from the addition of the methoxyethynyl anion to the carbonyl group of crotonaldehyde (G. Stork, 1962 B, 1964A). 

Figure 6.15 The infrared vibrational spectrum of crotonaldehyde. The parts marked (a), (b) and (c) refer to a 10 per cent (by volume) solution in CCI4, a 1 per cent solution in CCI4, and a thin liquid film, respectively. [Reproduced, with permission, from Bowles, A. J., George, W. O. and Maddams, W. F J. Chem. Soc. (B), 810, 1969]...

Table 6.4 Fundamental vibration wavenumbers of crotonaldehyde obtained from the infrared and Raman spectra...

An excess of crotonaldehyde or aUphatic, ahcyhc, and aromatic hydrocarbons and their derivatives is used as a solvent to produce compounds of molecular weights of 1000—5000 (25—28). After removal of unreacted components and solvent, the adduct referred to as polyester is decomposed in acidic media or by pyrolysis (29—36). Proper operation of acidic decomposition can give high yields of pure /n j ,/n7 j -2,4-hexadienoic acid, whereas the pyrolysis gives a mixture of isomers that must be converted to the pure trans,trans form. The thermal decomposition is carried out in the presence of alkaU or amine catalysts. A simultaneous codistillation of the sorbic acid as it forms and the component used as the solvent can simplify the process scheme. The catalyst remains in the reaction batch. Suitable solvents and entraining agents include most inert Hquids that bod at 200—300°C, eg, aUphatic hydrocarbons. When the polyester is spHt thermally at 170—180°C and the sorbic acid is distilled direcdy with the solvent, production and purification can be combined in a single step. The solvent can be reused after removal of the sorbic acid (34). The isomeric mixture can be converted to the thermodynamically more stable trans,trans form in the presence of iodine, alkaU, or sulfuric or hydrochloric acid (37,38). 

Preparing sorbic acid by reaction of crotonaldehyde and acetone followed by oxidation of the crotonyUdenacetone is of interest in the former Soviet Union (41,42) ... 

The acetaldehyde is particularly undesirableas it leads to the formation of crotonaldehyde (87), an impurity that adversely affects ethanol quaHty even at parts per million levels. 

In Figure 1.1.1 a,b an example is shown for scale-down to experimental conditions for the hydrogenation of crotonaldehyde to butanol ... 

The yields of Skraup/Doebner-von Miller reaction can be dramatically improved by running the reaction as a two-phase mixture. Reaction of crotonaldehyde with 30 in acidic ethanol provides only 10% of quinoline 31. However, when a toluene solution of crotonaldehyde is reacted with 30 (starting as the acetanilide) in 6M HCI at 100 °C for 2 h, quinoline 31 is isolated in 80% yield on 5kg scale. 

As an example of the system in which parallel and consecutive reactions occur simultaneously, we have chosen the hydrogenation of crotonaldehyde, which may lead through two two-stage paths (via butyraldehyde and via crotyl alcohol) to the same final product, butanol... 

Fig. 9. Dependence of relative molar concentrations Wj/nA0 of reaction components on reciprocal space velocity W/F (hr kg mole 1) in the parallel-consecutive hydrogenation of crotonaldehyde. Temperature 160°C, catalyst Pt-Fe/Si02 (1% wt. Pt, 0.7% Fe), initial molar ratio of reactants G = 10. The curves were calculated (1—crotonaldehyde, 2—butyraldehyde, 3—crotyl alcohol, 4—butanol) the points are experimental values.

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. 

Values of Constants ki (mole hr lkff ialm Jl) and of Adsorption Coefficients K j (atm-1) in Parallel-Consecutive Hydrogenation of Crotonaldehyde... 

It is noteworthy that even a separate treatment of the initial data on branched reactions (1) and (2) (hydrogenation of crotonaldehyde to butyr-aldehyde and to crotyl alcohol) results in practically the same values of the adsorption coefficient of crotonaldehyde (17 and 19 atm-1)- This indicates that the adsorbed form of crotonaldehyde is the same in both reactions. From the kinetic viewpoint it means that the ratio of the initial rates of both branched reactions of crotonaldehyde is constant, as follows from Eq. (31) simplified for the initial rate, and that the selectivity of the formation of butyraldehyde and crotyl alcohol is therefore independent of the initial partial pressure of crotonaldehyde. This may be the consequence of a very similar chemical nature of both reaction branches. 

The reaction of crotonaldehyde and methyl vinyl ketone with thiophenol in the presence of anhydrous hydrogen chloride effects conjugate addition of thiophenol as well as acetal formation. The resulting j3-phenylthio thioacetals are converted to 1-phenylthio-and 2-phenylthio-1,3-butadiene, respectively, upon reaction with 2 equivalents of copper(I) trifluoromethanesulfonate (Table I). The copper(I)-induced heterolysis of carbon-sulfur bonds has also been used to effect pinacol-type rearrangements of bis(phenyl-thio)methyl carbinols. Thus the addition of bis(phenyl-thio)methyllithium to ketones and aldehydes followed by copper(I)-induced rearrangement results in a one-carbon ring expansion or chain-insertion transformation which gives a-phenylthio ketones. Monothioketals of 1,4-diketones are cyclized to 2,5-disubstituted furans by the action of copper(I) trifluoromethanesulfonate. ... 

It is often said that the property of acidity is manifest only in the presence of a base, and NMR studies of probe molecules became common following studies of amines by Ellis [4] and Maciel [5, 6] and phosphines by Lunsford [7] in the early to mid 80s. More recently, the maturation of variable temperature MAS NMR has permitted the study of reactive probe molecules which are revealing not only in themselves but also in the intermediates and products that they form on the solid acid. We carried out detailed studies of aldol reactions in zeolites beginning with the early 1993 report of the synthesis of crotonaldehyde from acetaldehyde in HZSM-5 [8] and continuing through investigations of acetone, cyclopentanone [9] and propanal [10], The formation of mesityl oxide 1, from dimerization and dehydration of... 

The detonation was put down to the presence of crotonaldehyde peroxide or ether peroxide. 

A recent patent describes the synthesis and catalytic use of Al-containing TUD-1 materials. Some of the reactions demonstrated inclnde hydrogenation of mesitylene (Pt as active metal) and dehydration of 1-phenyl-ethanol to styrene. Several other conceptnal reactions were also described, amongst others the Diels-Alder reaction of crotonaldehyde and dicyclopentadiene and the amination of phenol with ammonia. 

Sedricks, W and Kenney, C. N., Partial wetting in trickle bed reactors—the reduction of crotonaldehyde over a palladium catalyst. Chem. Eng. Sci. 28, 558-1261 (1973). 

Butyrchloral has been prepared by chlorination of acetaldehyde 2 and of paraldehyde. Butyrchloral hydrate has been prepared by treatment of a,j8-dichlorobutyraldehyde with chlorine and water.3 Butyrchloral has also been prepared4 by treatment of crotonaldehyde with hydrogen chloride followed by chlorination. Brown and Plump have used a procedure similar to the one described here.3... 

Dining distillation of 2-propanol recovered from the reduction of crotonaldehyde with isopropanol/aluminium isopropoxide, a violent explosion occurred. This was attributed to peroxidised diisopropyl ether (a possible by-product) or to peroxidised crotonaldehyde. An alternative or additional possibility is that the isopropanol may have contained traces of a higher secondary alcohol (e.g. 2-butanol) which would be oxidised during the Meerwein-Ponndorf reduction procedure to 2-butanone. The latter would then effectively sensitise the isopropanol or other peroxidisable species to peroxidation. 

A procedure using a phase-transfer catalyst is employed to prevent the rapid polymerisation of crotonaldehyde dining the Robinson annulation reaction. 

Sorbic acid has been prepared from crotonaldehyde 1 5 or aldol6 and malonic acid in pyridine solution by hydrogen peroxide oxidation of the condensation product of crotonaldehyde and pyruvic acid 7 and by the action of alkali on 3-hydroxy-4-hexenoic acid,8 9 /3,5-disulfo-w-caproic acid,10 and parasorbic acid.1112... 

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