Acrolein, trimerization

The main use of acrolein is to produce acrylic acid and its esters. Acrolein is also an intermediate in the synthesis of pharmaceuticals and herhicides. It may also he used to produce glycerol hy reaction with isopropanol (discussed later in this chapter). 2-Hexanedial, which could he a precursor for adipic acid and hexamethylene-diamine, may he prepared from acrolein Tail to tail dimenization of acrolein using ruthenium catalyst produces trans-2-hexanedial. The trimer, trans-6-hydroxy-5-formyl-2,7-octadienal is coproduced. Acrolein, may also he a precursor for 1,3-propanediol. Hydrolysis of acrolein produces 3-hydroxypropionalde-hyde which could he hydrogenated to 1,3-propanediol. ... 

Figure 22.7. The major DNA lesions of the lipid peroxidation products. (A) DNA lesions produced by malondialdehyde. Mi denotes the monomeric form of malondialdehyde. Malo-ndialdehyde can polymerize to form dimers and trimers that can also react with DNA. The resulting lesions are designated as M2 and M3, respectively (c.g., M2G). These lesions, however, may not be significant in cells as polymerization of malondialdehyde is relatively slow at neutral pH. (B) The l,7V2-propano-dG DNA adducts produced by acrolein, crotonaldehyde, and 4-hydroxy-2-nonenal (HNE). Stereochemistry is not shown. The l.A -acrolcin-dG consists of three isomers. The 1, AAcrotonaldchyde-dG consists of two isomers. The FAAlINF-dGconsistsof four isomers. (C)EthenoDNAadductsproduced by 2,3-epoxy-4-hydroxynonenal. Further oxidation of 4-hydroxynonenal produces 2,3-epoxy-4-hydroxynonenal, which reacts with DNA to form the exocyclic etheno adducts.

The Diels-Alder cycloaddition is known to proceed through a cis-addition in such a manner that cis 1,8-dioxaoctahydronaphthalene 3 is the mtgor product. Small amounts of its regioisomer, cis 1,5-dioxaoctahydronaphthalene 4 and its trans isomer, trans-l,8-dioxa-octahydronaphthalene 5 resulting from the acid catalyzed rearrangement of 3 were also identified. Additionally, dimers and trimers resulting from self-addition of acrolein or addition of acrolein to the different dioxaoctahydronaphthalene adducts (3.4,5.) were also detected. Table 1 reports the initial reaction rates and the maximum yields for the conversion of dihydropyran and acrolein into cis 1,8-dioxaoctahydronaphthalene at 0°C. 

Dimers consist of molecules made up of two identical smaller molecules (monomers). For example, acrolein dimer ( 31140)2, is made up of two acrolein molecules (C3H4O). Trimers and tetramers are made up of three and four monomers, respectively. Any molecule with five or more monomers is a polymer. 

Encouraged by the success with fluoral, fluoroketones have also been investigated systematically in the MBH reaction. Since 1,1,1-trifluoroacetone is known to trimerize in the presence of amines, lower yields of MBH adducts were obtained at lower temperature when treated with acrolein and acrylonitrile. With methyl acrylate and MVK, however, only a polymeric material was isolated under the MBH reaction conditions. 

A similar trimerization strategy of acrolein (285) was used recently by Hong et al. (Scheme 76) early in the total synthesis of montiporyne F (334) (S02), a natural product isolated from the coral Montipora sp. exhibiting cytotoxic activity against human tumor cell lines (307). Importantly, trimerization of 285 in the presence of (5)-12 and several additives always provided the racemic dialdehyde 335. Although this is an example of a procedure where no stereodifferentiation... 

Hong BC, Nimje RY, Yang CY (2007) The Organocatalytic Direct Self-Trimerization of Acrolein Application to the Total Synthesis of Montiporyne F. Tetrahedron Lett 48 1121... 

PTT is melt-polymerized by either the transesterification of PDO with DMT or by the direct esterification of PDO with TPA. The process is similar to the polymerization of PET but with several important differences. Since the reactivity of PDO is much lower than that of ethylene glycol, hot catalysts such as titanium butoxide (12) and dibutyl tin oxide (13), normally too fast for PET, are used to polymerize PTT. Melt polymerization is carried out between 250 and 275°C, about 40° C lower than that used for PET. PTT has different polymerization side reaction products. Instead of cyclic trimers, PTT produces cyclic dimers. It also gives off acrolein and allyl alcohol instead of acetaldehyde gaseous by-products. Acrolein requires special handling and disposal. 

Hong, B.-C., Nimje, R.Y., and Yang, C.-Y (2007) The orgsnocatalytic direct self-trimerization of acrolein application to the total synthesis of montiporyne F. Tetrahedron Lett., 48, 1121-1125. 

At 26.7 mbar pressure 40% weight toss main product is 2,4-diphenyl thiophene at least 11 unidentified minor products CO2, H2O, butene, isobutene, dimethyl ketene, styrene, methacrylic acid, succinic-type 5-membered cyclic anhydrides Chlorotrifluoroethylene, styrene, HQ, chloropentafluoropropene, ethene, chloroethene, totuene, a-melhylstyiene, dimer and trimer structures with some unsaturation S1F4 (fiom reaction of HF with glass). Distribution of products varies with polymer composition CO, CO2, propene, isobutene, dimethyl ketene, acrolein, allyl alcohol, toluene, styrene, cl-methylstyrene, ethylbenzene, glycidol, glycidylmethacrylate product distribution depends on copolymer composition... 

It has been reported that 1,1,1-trifluoroacetone trimeiizes in the presence of amines (Scheme 8) (18). Although we observed some reaction in die case of perfluoroalkyl aldehydes, ethyl acrylate and methyl vinyl ketone failed to react with 1,1,1-trifluoroacetone. Acrolein and acrylonitrile provided -10% yield of the product along with the trimer. 

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