f****n
发帖数: 95 | 1 我在为含氟的丙烯酸酯/丙烯酰胺类高分子寻找good solvent,发现trifluoroacetic
acid (TFA)的溶解能力特别强，很好用。可是，高分子（白色粉末）溶解于新鲜的TFA
之后溶液由无色透明慢慢变为淡黄色透明。
是不是因为TFA是强酸有所谓的发烟现象？浓盐酸就是淡黄色，因为含有少量杂质Cl2
。另外， 含卤素或含硝基的化合物容易变颜色,是少量变质导致的吗？
谢谢！
p.s.
查到有这么一句：“olutions of proteins in trifluoroacetic acid prepared in
vacuo
are clear and colourless; on exposure to air, a purple colour develops.”不
解中···
Nature 174, 509 (11 September 1954); doi:10.1038/174509a0
Anhydrous Trifluoroacetic Acid as a Solvent for Proteins
JOSEPH J. KATZ
Chemistry Di... 阅读全帖 |
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T**********e
发帖数: 29576 | 2
Terri 大脑基本都液化了，只有植物神经功能。
Left: CT scan of normal brain; Right: Schiavo's 2002 CT scan provided by
Ronald Cranford, showing loss of brain tissue. The black area is liquid,
indicating hydrocephalus ex vacuo.[31] The small white piece in the right
image is the Thalamic stimulator implanted in her brain. |
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T**********e
发帖数: 29576 | 3
看了医生展示了脑CT,她大脑基本液化了 (右).
Left: CT scan of normal brain; Right: Schiavo's 2002 CT scan provided by
Ronald Cranford, showing loss of brain tissue. The black area is liquid,
indicating hydrocephalus ex vacuo.[31] The small white piece in the right
image is the Thalamic stimulator implanted in her brain. |
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X******i
发帖数: 1384 | 4 Cooper 小哥大半夜给我发实验计划，我打开一看，不愧是名校出来的，说话都不会好
好说，实验步骤真空操作我们一般就说under vacuum吧，人家小哥用in-vacuo，还加斜
体，唯恐大家不知道他拉丁文说的溜。我们要说证实了什么，基本会用confirm这个词
，人家用的是高大上的corroborate，我还得查字典才知道这词什么意思。伴随的现象
我们一般用accompany,人家又用了一个偏词concomitant。看完了小哥的实验计划，我
脑细胞死了一半，为自己词汇量的贫乏而自卑。再看看人家，如此优雅低调的炫耀了自
己的水平。 |
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m*****e
发帖数: 1506 | 5 dissolve in CH2Cl2 (or other solvents), dy over Na2SO4, remove solvent, dry
in vacuo.
washed |
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m*****e
发帖数: 1506 | 6 load on a short column packed with nuetral alumina, then flash with hexane,
concentrate, and dry in vacuo. Purifed VBS should be a colorless liquid.
Store in a freezer at -20 degree C.
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