2.46 - 6.97%Chromat.; 93.03 - 97.54%Chromat. |
sulfuric acid; at 80 - 90℃; under 30 - 40 Torr; for 1.75 - 4h;Product distribution / selectivity; |
A 500 ml 3-neck round bottom flask was charged with 36.64g (0.3 mol) erythritol (obtained from the Cargill Company of Wayzata, MN) and 346.01g (2.4 mol) ethyl levulinate (obtained from the Sigma Aldrich Company of St. Louis, MO). The flask was equipped with a Dean Stark trap, mechanical stirrer, and thermocouple. The contents of the flask were heated to 80C, at which point15.99mul of concentrated sulfuric acid (obtained from the Sigma Aldrich Company) was added to the reaction flask via a metered microliter pipette. A vacuum was applied to the reaction flask, slowly bringing the pressure down to 40 torr. This pressure was maintained with stirring while liquid was observed to collect in the Dean Stark trap. About 1 hour, 45 minutes after addition of sulfuric acid, the vacuum was released and a small sample was removed from the reaction flask. The vacuum was then reestablished. After an additional 1 hour, 15 minutes reaction time, liquid had stopped collecting in the Dean Stark trap. The vacuum was released, and the contents of the flask were allowed to cool to ambient temperature. A second sample was removed from the reaction flask.Both samples removed were analyzed by GC-MS. The GC portions of the analyses are shown in FIGS. 2 A and 2B. FIG. 2 A shows the GC of the sample removed after the initial 1 hour, 45 minutes of reaction time. FIG 2B shows the GC of the sample removed after a total of 3 hours reaction time, or an additional 1 hour, 15 minutes after the first sample was taken. The percentages of products were calculated by disregarding the presence of ethyl levulinate, because of the excess molar equivalents of ethyl levulinate used in the reaction. Thus, the percentages of erythritol, the monoketal of erythritol with one molar equivalent of ethyl levulinate, and the bisketal of erythritol with two molar equivalents of ethyl levulinate were calculated by determination of their relative GC peak areas. The sample removed at 1 hour, 45 minutes was found to contain 93.03% of the bisketal, 6.97% of the monoketal, and 0% erythritol by GC peak area. The sample removed after the additional 1 hour, 15 minutes reaction time was found to contain 100% of the bisketal.; Examples 2-11Using the procedure of Example 1, various polyketal compounds were synthesized. Table 1 shows reagents, temperature, and time of reaction as well as the percent yield of products obtained at the end of the reaction, as determined by GC-MS (GC peak area) employing the calculation described in Example 1. Unless noted, the pressure of the reaction vessel was 30 torr during the reaction.Butyl levulinate was obtained from the Sigma Aldrich Company of St. Louis, MO. Ethyl acetoacetate was obtained from Acros Organics of Geel, Belgium. Sorbitol was obtained from Acros Organics. Mannitol was obtained from the Sigma Aldrich Company. Pentaerythritol was obtained from the Sigma Aldrich Company. Diglycerol was obtained from Tokyo Kasei Kogyo of Tokyo, Japan. Sulfamic acid was obtained from the Sigma Aldrich Company. Amberlyst-15 was obtained from the Rohm and Haas Company of Philadelphia, PA. |
1.00%Chromat.; 99.00%Chromat. |
Amberlyst-15; at 90℃; under 30 Torr; for 8h;Product distribution / selectivity; |
Using the procedure of Example 1, various polyketal compounds were synthesized. Table 1 shows reagents, temperature, and time of reaction as well as the percent yield of products obtained at the end of the reaction, as determined by GC-MS (GC peak area) employing the calculation described in Example 1. Unless noted, the pressure of the reaction vessel was 30 torr during the reaction.Butyl levulinate was obtained from the Sigma Aldrich Company of St. Louis, MO. Ethyl acetoacetate was obtained from Acros Organics of Geel, Belgium. Sorbitol was obtained from Acros Organics. Mannitol was obtained from the Sigma Aldrich Company. Pentaerythritol was obtained from the Sigma Aldrich Company. Diglycerol was obtained from Tokyo Kasei Kogyo of Tokyo, Japan. Sulfamic acid was obtained from the Sigma Aldrich Company. Amberlyst-15 was obtained from the Rohm and Haas Company of Philadelphia, PA. |