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下列單質(zhì)中,Z容易與氫氣發(fā)生反應(yīng)的是 A.O 2 B.N 2 C.F 2 D.Cl

*座淺夢兒 2018-12-01 17:34:09 326  瀏覽
  • 下列單質(zhì)中,Z容易與氫氣發(fā)生反應(yīng)的是 A.O 2 B.N 2 C.F 2 D.Cl 2

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下列單質(zhì)中,Z容易與氫氣發(fā)生反應(yīng)的是 A.O 2 B.N 2 C.F 2 D.Cl
下列單質(zhì)中,Z容易與氫氣發(fā)生反應(yīng)的是 A.O 2 B.N 2 C.F 2 D.Cl 2
2018-12-01 17:34:09 326 0
下列單質(zhì)中Z容易和氫氣發(fā)生反應(yīng)的是
A氧氣B氮?dú)釩F2D氯氣
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f氣與氯氣哪個(gè)Z容易與氫氣發(fā)生反應(yīng)
 
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同質(zhì)量的下列氣體中,所含原子數(shù)Z多的是 A.CH 4 B.CO 2 C.H 2 S D.N
同質(zhì)量的下列氣體中,所含原子數(shù)Z多的是 A.CH 4 B.CO 2 C.H 2 S D.N 2
2018-12-18 02:24:00 462 0
在標(biāo)準(zhǔn)狀況下,密度Z小的氣體是( ?。? A.NO 2 B.SO 2 C.O 2 D.CH
在標(biāo)準(zhǔn)狀況下,密度Z小的氣體是( ?。? A.NO 2 B.SO 2 C.O 2 D.CH 4
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英語翻譯(2)
Keywords:Epoxides;Amines;2-Aminoalcohols;Yttriumnitratehexahydrate;RegioselectivityAminoalcoholsconstituteanimportantclassofcompoundshavingbothchemicalandbiologicalapplic... Keywords: Epoxides; Amines; 2-Amino alcohols; Yttrium nitrate hexahydrate; Regioselectivity Amino alcohols constitute an important class of compoundshaving both chemical and biological applications. They are important pharmacophores present in various inhibitors and are used as building blocks for the synthesis of biologically active natural products, insecticidal agents and chiral auxillaries for asymmetric reactions.1a–f They act as starting materials for the synthesis of oxazolines which are useful in the polymer industry.1g Owing to their widespread applications, the synthesis of amino alcohols has received much attention in recent years. Traditionally, 2-amino alcohols are prepared by heating an epoxide with an excess of amine at elevated temperature. The use of a high temperature leads to undesired side reactions and also limits the applicability towards temperature sensitive substrates. To overcome these drawbacks various promoters such as ZnCl2,2 ScOTf,3 MgBr2OEt2,4 67 9 bismuth salts,5 CoCl2, CuBF4, DIPAT,8 Ti(OiPr)4, 1011 12TaCl5, ZrCl4, Sm(OTf)3, potassium dodecatungstocobaltate, 13 and aluminosilicate14 have been employed for the above transformation. The use of non-conventional techniques such as microwave irradiation at elevated temperaturehas also been reported.15 Recently, the use of Al(OTf)3 (1 mol %) as catalyst in toluene at reflux has also been reported.16 Although significant advances have been made in this area, low regioselectivity, longer reaction time, use of elevated temperature, high catalyst loading, toxic solvents and lower substrate compatibilitylimit their applications.Thus there is a need to develop an efficient catalytic protocol for ring opening of various epoxides with aliphatic, aromatic andheteroaromatic amines under ambient conditions 展開
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請逐步分析以下題中所有步驟目的及加星號的試劑的簡單性質(zhì):準(zhǔn)確稱取0.1500g Mg-Al合金(含有鎂鋁硅等)試樣于150毫升燒杯中,加入約10mL*混合酸,并立即加蓋表面皿,待試樣溶解后,用水沖洗表面皿和杯壁,將溶液轉(zhuǎn)移至100mL容量瓶中,稀釋至刻度,搖勻。用移... 請逐步分析以下題中所有步驟目的及加星號的試劑的簡單性質(zhì):準(zhǔn)確稱取0.1500g Mg-Al合金(含有鎂鋁硅等)試樣于150毫升燒杯中,加入約10mL*混合酸,并立即加蓋表面皿,待試樣溶解后,用水沖洗表面皿和杯壁,將溶液轉(zhuǎn)移至100mL容量瓶中,稀釋至刻度,搖勻。用移液管吸取25mL試液于250mL錐形瓶中,加入0.02mol\L的EDTA溶液20mL,*二甲酚橙指示劑,用氨水調(diào)至溶液恰呈紫紅色,然后滴加稀鹽酸三滴,將溶液煮沸三分鐘左右,冷卻,加入百分之20的六次甲基四胺溶液20mL,此時(shí)溶液應(yīng)呈黃色,如不呈黃色,可再用鹽酸調(diào)節(jié)。再補(bǔ)加二甲酚橙2滴,用cmol\L的*鋅標(biāo)準(zhǔn)溶液滴定至溶液由黃色變?yōu)樽霞t色,用去鋅標(biāo)準(zhǔn)溶液體積V1毫升,加入20%NH4F溶液10mL,將溶液加熱到微沸,流水冷卻,再補(bǔ)加稀鹽酸使溶液顯黃色。再用cmol\L的鋅標(biāo)準(zhǔn)溶液滴定至溶液由黃色變?yōu)榧t紫色時(shí),即為終點(diǎn),用去鋅標(biāo)準(zhǔn)溶液體積V2. 附問題 <1>列出計(jì)算合金中鋁的質(zhì)量分?jǐn)?shù)的表達(dá)式 <2>為什么不用標(biāo)準(zhǔn)的EDTA溶液直接滴定來測鋁離子 <3>加入20%NH4F溶液10mL的目的是什么 <4>實(shí)驗(yàn)完畢后要注意什么 展開
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