r******0
发帖数: 2753 | 1 I really doubt about that. Polymers usually have broad peaks in H-NMR. The
difference between chain and chain ends are too small and they may overlap. If
you did see the difference, you may need to consider that if the chain ends
are still -OH. Check the standard H-NMR spectrum of
HO-CH2CH2-O-CH2CH2-O-CH2CH2-O-CH2CH2-OH, you may get some idea. Anyway, good
luck. |
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b*****r
发帖数: 203 | 2 Structure is:
HO-CH2CH2-O-CH2CH2-O-CH2CH2-O-CH2-CH2-OH
water loss peak is at the two ends, additional 28 loss is CH2CH2OH, further
16 loss is O.
You should put me as one of the coauthors -- just kidding.
My suggestion is next time you might want to put your contact information
there and mention that people with signficant contribution can be considered
as a coauthor, then people will be willing to spend a lot of time on your
problem.
Without |
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d*********2
发帖数: 48111 | 3 ch2ch2
chch
哥化学水平如何?
我还能写苯环, 对二甲苯px |
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d******s
发帖数: 674 | 4 同意二楼的说法
下载这个软件‘molecular weight calculator’就可以计算exact mass
http://www.alchemistmatt.com/
MS/MS用来鉴定结构最多是用在结构确认方面，而且液质联用的谱库很少而且数据严重
不全（相对于气质来说）。
从你上传的MS/MS来看，只能看出来173-->155 （-H2O， maybe a -OH group on your
compound) -->129 （-O, maybe a -O- group) -->101 (-28, -CH2CH2-)
这个MS/MS应该不是高分辨质谱吧？
很奇怪的是173有一个5%的174同位素峰，155也是，不知道是不是因为是合成产物的原
因。 从同位素比例来看很像S，难道是double-charged？
给点未知物的信息好不好？虽然看谱图比较有意思，摸瞎也太zturn了一点
BTW，鉴定未知物的结构不都是做NMR么？ |
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s********t
发帖数: 86 | 5 CH2 methylene
CH2CH2 ethylene
CH2CH2CH2 propylene??? |
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c*s
发帖数: 2145 | 6 【 以下文字转载自 Chemistry 讨论区,原文如下 】
发信人: weiss (weiss), 信区: Chemistry
标 题: help: solubility of two polymers in water???
发信站: The unknown SPACE (Mon Nov 4 14:25:47 2002) WWW-POST
poly-ethylene glycol: OH-(CH2CH2-O)n-H
poly-propylene glycol: OH-(CH(CH3)CH2-O)n-H
very simple polymers, but can't find their solubility in water. any one
happens
to know this??
Just want to compare them, have an idea about how the methy group can change
the solubility.
thanks!! |
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a***n
发帖数: 578 | 7 theoretically, heihei, you can deposite a molecular monolayer on the glass and
put another one on it. It will work.
The molecule should have acid group at both end.
such as HOOC-CH2CH2...-COOH.
If it works, please let me know. hoho.
as a reference, HS-CH2-CH2...-CH2-SH can glue two pieces of gold together.
more
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