Isolation of an alkaloid课件.pptVIP

Isolation of an alkaloid: Caffeine Isolation of an alkaloid: Caffeine Tea and coffee are popular beverages known from antiquity. Both are rich in caffeine, a central nervous system(CNS), respiratory, and cardiac stimulant. Caffeine is also a diuretic agent (tending to increase urine production) and can produce nervousness, insomnia, and racing heartbeat (tachycardia) .Heavy consumption can lead to a caffeine dependence such as headache and even nausea can be experienced without it . 自古以来，茶和咖啡就是人们熟知的饮料。它们都含有丰富的咖啡因，一种中枢神经系统、呼吸和心脏的刺激物（强心剂）。咖啡因也是一种利尿剂（使尿量增加），并且能产生焦虑、失眠和心跳加速（心动过速）。过量使用会导致咖啡因依赖，如产生咖啡因缺乏时的头痛、恶心等感觉。 Caffeine is one of the alkaloids ,witch are basic nitrogen –containing compound found in certain plant materials. Structurally, it is 1,3,7-trimethylxanthine. It is also a derivative of purine and is therefore related to the purine bases in nuclear acids and to uric acid. Two closely related compound are the dimethylxanthines, theophylline ,which occurs along with caffeine in tea ,and theobromine ,witch occurs instead of caffeine in cocoa . 咖啡因是一种生物碱，是从某些植物原料中发现的一种基本含氮化合物。结构上，它是1,3,7-三甲基嘌呤。它也是嘌呤衍生物，因此，与核酸和尿酸中的嘌呤碱有相似之处。两种密切相关的化合物是茶叶中伴随着咖啡因一同出现的二甲基黄嘌呤，即茶碱，另一种是出现在可可中的可可碱。 The caffeine content of caffeine beans is about 1%-2% by weight and in tea leaves is about 2%-4%. Because of differences in methods of brewing ,however ,an average cup of coffee contains about twice as much as caffeine as a cup of tea (100mg versus 50 mg). Cola nuts are aslo a rich source of caffeine ,and the caffeine content of cola beverages typically runs 40-50mg per 12oz container .Many commercial analgesic (pain-killing) medicine also contain caffeine to counteract the drowsiness often produced by the active ingredients in such preparation .The most important commercial source of caffeine is as a by-product in the production of decaffeinated coffee . 咖啡豆中咖啡因的质量含量大约为1%-2%，茶叶中大约是2%-4%。但是由于制取方法的不同，一杯咖啡中咖啡因的含量是等质量一杯茶中的2倍。可乐果也是咖啡因的一种丰富的来源，最具典型代表性的是可乐饮料中的咖啡因含量可达到每12盎司含40-50mg。许多商业镇痛药中也含有咖啡因用来抵制其制备过