什麼是醯胺

兩類含氮有機化合物的統稱，與氨、胺有關，幷包含一個羥基（－C＝O；參閱functional group）。第一類，共價醯胺是由氨基（－NR2，其中R可以代表一個氫原子，或代表一個有機的聯合基團，如甲基）取代酸中的羥基（－OH）而生成。由羧酸製得的醯胺稱羧醯胺，除了最簡單的甲醯胺爲液體外，均爲固體。它們不導電，具高沸點，液態的共價醯胺是優良的溶劑。簡單的有機共價醯胺沒有實際的天然來源，然而生命系統中的和蛋白質都是些帶鍵（參閱covalent bond）的長鏈（聚合物），這些都是醯胺鏈結。尿素是一種帶兩個氨基的醯胺。具有重要商業價值的共價醯胺中有若干種用作溶劑；其他的有磺胺藥以及尼龍。第二類，離子（類似鹽類）醯胺是將共價醯胺、胺或氨用能起反應的金屬（如鈉）處理後得到的，具有很強的礆性。

amide

Any member of either of two classes of nitrogen-containing organic compounds related to ammonia and amines and containing a carbonyl group (&singlehorzbond;C&doublehorzbond;O; see functional group). The first class, covalent amides are formed by replacing the hydroxyl group (&singlehorzbond;OH) of an acid with an amino group (&singlehorzbond;NR2, in which R may represent a hydrogen atom or an organic combining group, such as methyl). Amides formed from carboxylic acids, called carboxamides, are solids except for the simplest, formamide, a liquid. They do not conduct electricity, have high boiling points, and (when liquid) are good solvents. There are no practical natural sources of simple covalent amides, but the peptides and proteins in living systems are long chains (polymers) with peptide bonds (see covalent bond), which are amide linkages. Urea is an amide with two amino groups. Commercially important covalent amides include several used as solvents; others are the sulfa drugs and nylon. The second class, ionic (salt-like) amides (see ionic bond), are made by treating a covalent amide, an amine, or ammonia with a reactive metal (e.g., sodium) and are strongly alkaline.