During the preparation of UPR from dicyclopentadiene, the following two reactions occur:

　　1.二醇- alder反应:在160—170℃下，二环戊二烯分解成环戊二烯(CPD)， CPD在170℃以上与山东马来酸酐反应，然后与二元醇、二元酸酯化反应。这种方法也称为“酸酐法”。也可以将山东马来酸酐与二元醇酯化制备单酯，在170 ~ 175℃条件下加入二环戊二烯，在200℃条件下完成酯化反应。

　　1. Diol alder reaction: at 160-170 ℃, dicyclopentadiene decomposes into cyclopentadiene (CPD), which reacts with Shandong maleic anhydride above 170 ℃, and then esterifies with diol and dicarboxylic acid. This method is also known as the "acid anhydride method". Shandong maleic anhydride and diol can also be esterified to prepare monoester. Dicyclopentadiene can be added at 170 ~ 175 ℃, and esterification can be completed at 200 ℃.

　　2. 二环戊二烯的直接加成:后来发现，在酸的催化作用下，可以将醇或酸直接加到二环戊二烯的双键上，形成醚或酯。这种直接加成反应可以通过以下四种方式进行:

　　2. Direct addition of dicyclopentadiene: it was later found that under the catalysis of acid, alcohol or acid can be directly added to the double bond of dicyclopentadiene to form ether or ester. The direct addition reaction can be carried out in the following four ways:

　　(1)初始方法:将山东马来酸酐、邻苯二酸酐、二醇、二环戊二烯全部放入反应器中，加热150℃，回流反应30-60分钟，再转为缩合，加热200℃完成酯化。

　　(1) Initial method: put Shandong maleic anhydride, phthalic anhydride, diol and dicyclopentadiene into the reactor, heat to 150 ℃, reflux reaction for 30-60 minutes, then convert to condensation, heat to 200 ℃ to complete esterification.

　　(2)水解法:先将山东马来酸酐在等摩尔水中加热80-100℃转化为马来酸酐，再降二环戊二烯快速完成反应。然后加入二元醇和改性酸，在200℃下完成酯化反应。

　　(2) Hydrolysis method: firstly, Shandong maleic anhydride is heated to 80-100 ℃ in equimolar water to be converted into maleic anhydride, and then dicyclopentadiene is reduced to complete the reaction quickly. After that, diol and modified acid were added and esterification was completed at 200 ℃.

　　(3)“半酯”法:先在150℃下由蝶齿酸酐与二元醇反应，再由蝶齿酸酐环化。然后，在150℃下，通过滴注二环戊二烯的方式，对蝶阀戊二烯双键上的羟基进行醚化或对蝶阀戊二烯双键上的羧基进行酯化。，酯化在200℃下完成。

　　(3) "Half ester" method: the reaction of diehydric anhydride with diol at 150 ℃, followed by cyclization of diehydric anhydride. Then, at 150 ℃, the hydroxyl group on the double bond of butterfly valve was etherified or the carboxyl group on the double bond of butterfly valve was esterified by dropping dicyclopentadiene. Finally, esterification was completed at 200 ℃.

　　(4)封端方法:在200℃下完成山东马来酸酐、邻苯二酸酐和二醇的酯化。当酸降低到较低的值时，反应冷却到160℃，加入人体双环戊二烯，封闭其端羟基和端基。

　　(4) Sealing method: the esterification of Shandong maleic anhydride, phthalic anhydride and diol was completed at 200 ℃. When the acid is reduced to a lower value, the reaction is cooled to 160 ℃, and dicyclopentadiene is added to block the end group and hydroxyl group.

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