Furfural dimethyl acetal

Thromboxane families (125) and (126) were prepared from the cycloadduct (128) between a bromo ketone (127) and 2-furfural dimethyl acetal, though the yields were not good (Scheme 30). ... 

A solvent effect on diastereoselectivity was also observed with other substrates (Table XVIII). Generally, when aromatic aldehydes (benzaldehyde, furfural, 2-thiophenecarbaldehyde) and benzaldehyde dimethyl acetal were used, the ratio of threo to erythro products increased in the following order... 

By GC-MS analysis, peaks 36, 37 and 39 were estimated to be 3-hydroxy-4,5-dimethyl-2(5H)-furanone, acetate of hydroxymethyl furfural and 4-pentyl-2-pentenolide, respectively. At this stage, the sample was too small to apply other analytical methods therefore, we tried to synthesize all the possible compounds using the synthetic approaches described in the following section. None of thethree synthetic products showed the characteristic sugary aroma that we had recognized in each separated fraction however, the yield of fraction 11-GC TRAP from molasses was calculated to be ca. 

Figure 5.2.10. Cellulose pyrolysate obtained at 59CP C by Py-GC/MS. The separation was done on a Carbowax type column. 1 CO2, 2 acetaldehyde, 3 acetone, 4 2-butanone, 5 2,3-butandione, 6 toluene, 7 water, 8 cyclopentanone, 9 methylfuran, 10 3-hydroxy-2-butanone, 11 hydroxypropanone, 12 cyclopent-1-en-2-one, 13 2-methylcyclopentenone, 14 acetic acid, 15 acetic acid anhydride, 16 furancarboxaldehyde, 17 methylcyclopentenone, 18 dimethylcyclopentenone, 19 5-methylfurancarboxaldehyde, 20 2,3-dihydro-2-furanone, 21 furan-2-methanol, 22 3-methylfuran-2-one, 23 2(5H)-furanone, 24 hydroxycyclopentenone, 25 3,5-dimethylcyclopentan-1,2-dione, 26 2-hydroxy-3-methyl-2-cyclopenten-1-one, 27 2-hydroxy-3-ethyl-2-cyclopenten-1-one, 28 2,3-dimethyl-2-cyclopenten-1-one, 29 phenol, 30 dimethylphenol, 31 3 thyl-2,4(3H,5H)-furandione, 32 3-butenoic acid, 33 1,4 3,6-dianhydro-a-D-glucopyranose, 34 5-(hydroxymethyl)-furfural.

A - 1,1-diethoxyrethane (acetal) B - Acetaldehyde C - Acetone D - Benzene E - Cyclohexane F - Methanol G -Butan-2-one (methyl ethyl ketone) H - 4-methylpentan-2-one (methyl isobutyl ketone) I - Propanol J -Propan-2-ol K - Butanol L - Butan-2-ol M - 2-methylpropanol (isobutanol) N - Furan-2-carbaldehyde (furfural) O - 2-methylpropan-2-ol (1,1-dimethyl alcohol) P - 2-methylbutan-2-ol Q - Pentan-2-ol R - Pentanol S - Hexanol T - Heptan-2-ol U - Hexan-2-ol V - Hexan-3-ol... 

C, and these are known not to be components of essential oil of Pistacia vera, but are the browning reaction products (e.g. furfural, 2-furanmethanol, acetylfuran, 2-furanone, 2,4-dimethyl-furan, furfuiyl acetate and furfuryl alcohol). Most of these components are low in concentration at 200 °C, however show a significant increase at 250 °C. The browning reaction products may be produced either by caramelization or by Maillard reactions during the higher temperatures of 200 and 250 °C. 

Whatever route of monomer preparation has been used purification processes are then necessary and these are usually the dominant element in the cost of butadiene production. Such purification is usually achieved by an extractive distillation procedure using such chemicals as cuprous ammonium acetate, furfural, acetonitrile, N-methyl pyrrolidone and dimethyl formamide. 

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