1) Closed ring by acid
酸关环
2) cyclization
[英][,saikli'zeiʃən] [美][,saɪklɪ'zeʃən, ,sɪklɪ-]
关环
1.
In our reactions,existing of a little water promoted the cyclization,and made the reduction and cyclization steps be accomplished in a single operation.
以L-酪氨酸为原料合成了化合物1和化合物2,化合物2与NaBH4在THF下回流过夜,还原完毕后加少量水继续回流7~8 h就可直接得到关环产物3,总产率为40。
2.
2,4-ditrichloromethyl-6-methyl-1,3,5-triazine(chloro-triazine), which was the intermediate of 2-methylamino-4-methoxyl-6-methyl-triazine, was synthesized from tritox through cyclization.
以乙腈为起始原料,经氯气氯化得到三氯乙腈,催化关环得2,4 双(三氯甲基)-6-甲基-1,3,5均三嗪(简称氯嗪),产物含量>98%(面积归一法),收率>50%,以该化合物合成2 甲氨基 4 甲氧基 6 甲基-三嗪(简称三嗪)的成本比老工艺"三聚氯氰"和"双氰胺钠"路线均降低50%以上,并且环境友好,已经实现工业化。
3.
2-Chloro-6-chloromethylbenzothiazole was synthesized from ethyl 4-aminobenzonic via five-step reactions including cyclization, diazotization bromination, substitution, reduction and chlorization.
4-氨基苯甲酸乙酯在乙酸中与硫氰化钾,溴素关环反应得到2-氨基-6-羧乙基苯并噻唑,用亚硝酸叔丁酯/溴化铜重氮化溴化得到2-溴-6-羧乙基苯并噻唑,再与硫氢化钠发应得到2-巯基-6-羧乙基苯并噻唑。
4) Naphthenic acid
环酸
5) key link
关键环节
1.
The importance of examines and value supervision and analysis on key links;
验工计价监理的重要性及关键环节分析
2.
The five key links in cost management;
成本管理的五大关键环节
3.
This paper unifies the collection-control substation operation management and summaries the misoperation reason and combs the key link to prevent the electrical.
本文结合集控站的运行管理,总结引发误操作的原因,梳理出现场防止电气误操作的关键环节,做好防止误操作的安全控制,杜绝误操作的发生。
6) environmental public relations
环境公关
补充资料：近关
1.离都城近的边关。 2.指出奔避难经由之处。亦指出奔。 3.指远行途中的第一关。
说明：补充资料仅用于学习参考，请勿用于其它任何用途。
参考词条