3- acrolein, condensation with

The necessary amine (XXXIX) was prepared from the acid dimerization product (XXXVIII) of acrolein. Condensation with XXVIIa using Mondon s erythrinane synthesis led to the lactam XL and thence to the amine XLI, which was resolved with dibenzoyltartaric acid. A compound of the same structure was prepared from jS-erythroidine via... 

The sulfur dioxide can be recovered and recycled. The myrcenol, after purification by distillation, can condense with acrolein to produce Lyral [31906-04-4], an important aldehyde with a strong-lasting odor similar to Lily-of-the-valley (92). 

Benzanthrone, in turn, is obtained from anthraquinone by reaction with glycerine and sulfuric acid in the presence of a reducing agent such as iron. Anthraquinone is initially reduced to anthrone, which is condensed with acrolein. Acrolein, on the other hand, is an intermediate of the reaction between glycerine and sulfu-... 

As in the synthesis of other bipyridines, several routes to 4,4 -bipyridine have been devised where one of the pyridine rings is built up from simpler components. For example, a dimer of acrolein reacts with ammonia and methanol in the presence of boron phosphate catalyst at 350°C to give a mixture of products including 4,4 -bipyridine (3.4% yield), and in a reaction akin to ones referred to with other bipyridines, 4-vinylpyridine reacts with substituted oxazoles in the presence of acid to give substituted 4,4 -bipyridines. ° ° Condensation of isonicotinaldehyde with acetaldehyde and ammonia at high temperatures in the presence of a catalyst also affords some 4,4 -bipyridine, and related processes give similar results,whereas pyran derivatives can be converted to 4,4 -bipyridine (56% conversion), for example, by reaction with ammonia and air at 350°C with a nickel-alumina catalyst. Likewise, 2,6-diphenyl-4-(4-pyridyl)pyrylium salts afford 2,6-... 

Under comparable conditions the submitters found that the corresponding dihydropyran derivatives were similarly obtained by the condensation of acrolein with methyl vinyl ether in 80-81% yield, with ethyl vinyl ether (77-85% yield), with w-butyl vinyl ether (82% yield), with ethyl isopropenyl ether (50% yield), and with w-butyl cyclohexenyl ether (40% yield). Other <, /3-un-saturated carbonyl compounds that have thus been condensed with ethyl vinyl ether are crotonaldehyde (87% yield), meth-acrolein (40% yield), a-ethyh/3-n-propylacrolein (54% yield), cinnamaldehyde (60% yield), /3-furylacrolein (85% yield), methyl vinyl ketone (50% yield), benzalacetone (75% yield), and benzal-acetophenone (74% yield). 

In the iron vessel 2 kgm. potassium bisulphate and 400 gm. potassium sulphate are placed, while 600 gm. glycerol of 28° B. are run in. The whole is then heated in an air-bath until the temperature inside the vessel reaches 100° C., when the reaction commences and a mixture of water and acrolein begins to distil. The temperatures in the first condenser and in the flask are then so regulated that the mixture of vapours enters the second condenser at a temperature of about 70° C. A considerable proportion of the water and compounds with higher boiling points is thus condensed in the flask while the acrolein, together with the remaining water vapour condenses in the second condenser and is collected in the appropriate receiver. 

The condensation of 4-phenyl-2-butanone (45) with ethyl cyanoacetate took place over Cs-X to give the product, 46, in only a 39% yield but when a magnesium oxide containing hydrotalcite clay was used a 75% yield of 46 was obtained (Eqn. 22.43). 8 Formaldehyde was condensed with acetaldehyde at 425°C over a ZSM-5 zeolite containing MgO. Acrolein was obtained in almost 70% yield. 9... 

While many phenanthrolines are available from commercial suppliers, the synthesis of this ligand from its various precursors is often necessary in the preparation of more elaborate structures. The earliest syntheses of (1) proceeded by dual Skraup condensation about o-phenylenediamine, in a single-pot reaction.1 2 The low reported yields of this reaction, along with failed subsequent attempts to improve upon it,17 led to the use of sequential Skraup or Dobner-Miller condensations, with isolation of the intermediate 8-aminoquinoline (2). Reaction of (2) with glycerol (3) or acrolein (4) in the presence of sulfuric or phosphoric acid and arsenic pentoxide produces (1) directly, Scheme 1.4,8-10,17,18... 

Like all aldehydes, this condenses with aniline to form acrolein-aniline. 

Reaction of the tertiariz-butylimine from acetaldehyde with (Et0)2 POCl, in the presence of two equivalents of base gives the corresponding ylide. This gives good yields of substituted acroleins on condensation with ketones and aldehydes. " ... 

When anthraquinone in which one of the carbonyl groups has been reduced to a methylene group is condensed with one molecule of acrolein, the product is 1 9 benzanthrene, (22) ... 

The condensation of formaldehyde and acetaldehyde has been studied by Dimi-triu et al. [22] in the vapor phase at 453-598 K using a pulse type microreactor. The main product was acrolein, obtained with a selectivity of ca 82% with conversion of 45 % acetaldehyde at 573 K. With such reactors it is difficult to make a good material balance because the products retained by the solid are not detected. Because of this the technique probably gives too optimistic a view of the catalytic results (selectivity and stability to coke deactivation). 

In the Skraup synthesis quinoline is formed by heating together aniline, glycerol, and nitrobenzene in the presence of sulphuric acid, which acts as a dehydrating agent. It is possible that the glycerol is first converted into acrolein, which condenses with aniline to form acrolein-aniline the latter is oxidized by the nitrobenzene to quinoline. These transformations are indicated by the following formulas —... 

MA, a three carbon dialdehyde, can experience a number of configurational modifications as discussed by Kwon and Watts (6). Enolization of the diketo form may take place. The enolic tautomer may further undergo molecular rearrangement into its open cis-, open trans-, or chelated forms. At pH 3 or lower, MA is chelated and exists as 3 hydroxy-acrolein above pH 6.5 MA is completely dissociated and exists as an enolate anion. Between pH 3 and 6.5, MA is an equilibrium mixture of enolate anion and chelated forms. MA (also malondialdehyde), is one of the main secondary products of lipid oxidation. It forms a pink color by condensing with 2 moles of TBA (7). 

Acrolein cyanhydrin 211 was converted into its methoxymethyl ether 212, in turn alkylated with 1,3-dibromopropane to give the key 6-carbon synthon 213. m-Methoxybenzoic acid was utilized as the ring A component. Reductive alkylation via dianion 215 led to dihydroaromatic intermediate 216 which was decarboxylated with ensuing aromatization using lead tetraacetate (or, alternatively, anodic oxidation) to afford 217 in excellent yield. Unmasking of the carbonyl function generated known enone 218 ° (see Volume 2, pp. 693,697), which was condensed with 2-methyl-1,3-cyclopentanedione 12 to produce prochiral trione 219 in high yield. The latter had been cyclized previously to (+) 15c and thence converted into estrone. Alternatively, trione 219 was cyclo-dehydrated to the well-known estrone precursor estrapentaene 193 (see Volume 2, pp. 697, 701, 705). 

Two synthetic routes predicted by LHASA for the synthesis of quinoline (24) are shown in Scheme 7. LHASA S first synthetic route was to have 2-amino-benzaldehyde (25) condense with acetaldehyde (26) to yield quinoline and water, which is essentially equivalent to the known synthesis of quinoline from the reaction of aniline with acetaldehyde and formaldehyde (77). When this transform was removed from consideration, LIMS A suggested nucleophilic addition of aniline (27) to acrolein (28) to yield quinoline and water, which is identical to a known synthesis of quinoline (75). 

Acrolein (80) was converted, with ethanol and p-toluenesulphonic acid, into the acetal 81 which was reacted with acetaldehyde (82) in the presence of benzoyl peroxide to give the ketone 83. The Horner-Emmons condensation with ethyl diethylphosphonoacetate 51 gave... 

It is generally accepted that this reaction involves the conversion of glycerol into acrolein and reduction of anthraquinone to anthrone, the latter undergoing the Aldol Condensation with acrolein. After that, the consecutive dehydration, cyclization, and oxidation afford the final product of benzanthrone. An illustration of the reaction mechanism is displayed here. 

Fluoromalonaldehyde (25), which exists in solution as the enol form Z configuration), has been condensed with heterocyclic JV -alkylinunonium salts to give y-fluoropentamethinecyanine dyes (see Scheme 23). Synthesis of the aldehyde (Scheme 22) involves hydrolysis of 2-fluoro-3-dimethylamino-acrolein, the product of Vilsmeier formylation of sodium fluoroacetate. - ... 

Dehydration and Hydration—Addition or removal of water from a compound may be accomplished by a catalyst. Dehydration may occur as an independent reaction or as a heterogeneous reaction such as the condensation of an alcohol with ammonia, or the formation of esters fi m alcohols and acids. Alcohols can be dehydrated to form olefins or ethers. Other dehydration reactions are glycerine to acrolein and acetic acid to acid anhydride. Olefins can be condensed with water to form ethers, aldehydes, ketones and alcohols. The hydration reactions are governed by pressure, temperature, and the mole ratio of reactants. High pressures are occasionally necessary to counteract dehydration tendency and promote hydration. 

When a mixture of aniline, nitrobenzene, glycerol and concentrated sulphuric acid is heated, a vigorous reaction occurs with the formation of quinoline. It is probable that the sulphuric acid first dehydrates the glycerol giving acrolein or acraldehyde (A), which then condenses at its double bond with the amino group of the aniline to give acrolein-aniline (B), The latter in its enol... 

The base-catalyzed reaction of acetaldehyde with excess formaldehyde [50-00-0] is the commercial route to pentaerythritol [115-77-5]. The aldol condensation of three moles of formaldehyde with one mole of acetaldehyde is foUowed by a crossed Cannizzaro reaction between pentaerythrose, the intermediate product, and formaldehyde to give pentaerythritol (57). The process proceeds to completion without isolation of the intermediate. Pentaerythrose [3818-32-4] has also been made by condensing acetaldehyde and formaldehyde at 45°C using magnesium oxide as a catalyst (58). The vapor-phase reaction of acetaldehyde and formaldehyde at 475°C over a catalyst composed of lanthanum oxide on siHca gel gives acrolein [107-02-8] (59). 

Acrolein reacts slowly in water to form 3-hydroxypropionaldehyde and then other condensation products from aldol and Michael reactions. Water dissolved in acrolein does not present a hazard. The reaction of acrolein with water is exothermic and the reaction proceeds slowly in dilute aqueous solution. This will be hazardous in a two-phase adiabatic system in which acrolein is suppHed from the upper layer to replenish that consumed in the lower, aqueous, layer. The rate at which these reactions occur will depend on the nature of the impurities in the water, the volume of the water layer, and the rate... 

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