乙酸乙酯

Thus, the thermodynamic equilibrium was shifted and the yield of cyclic carbonates was improved.

在乙腈体系中，以不同的乙酸盐作催化剂，研究了CO2与二醇合成环状碳酸酯的反应。

Methods: fudr was esterified with acetic anhydride in the presence of pyridine and 4 dimethylaminopyridine.

在吡啶和4 二甲氨基吡啶存在时，fudr与乙酸酐反应，制备氟尿苷二乙酸酯，并测定其核磁共振氢谱。rp hplc测定其在正辛醇和磷酸盐缓冲液中的分配系数及不同ph缓冲液和组织匀浆中的稳定性。

Treatment of the diacetoxy-calix [4] arene with a series of ditosylates in dry MeCN in the presence of NaOH resulted in formation of electron-rich calix [4] areneocrowns, which reacted with 4, 4'-bipyrindinium and p-bis -benzene at room temperature in dry MeCN to afford self-assembling [2] catenanes by π-π stacking interaction.

以杯[4]芳烃为原料，通过三氟乙酸铊将其氧化成醌，醌类化合物在Zn粉、冰醋酸、少量盐酸和过量的乙酸酐中反应得到双乙酰化产物，利用氢氧化钠使其水解，然后再与各种对甲苯磺酸二酯进行环化反应，得到一系列具有富电子空腔的杯[4]芳烃并冠醚。

I urge any American living outside the country to get an early start checking his/her registration and receiving an absentee ballot, because it can take a while.

我奉劝身在国外的所有美国人早点着手核对登记表，并接收缺席选举人票，因为这得花点时间。

He is too young to join the army.

他太年轻了，还不能参军。