ORGLIST:Drying of THF

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From: Hamilton M. Viana (hmviana$##$uol.com.br)
Date: Fri Oct 10 2003 - 07:19:27 EDT


Fellows,

Could anybody give a good dryer agent for THF?
I intend to set up a small colunm after a condenser. Usually my THF leaves
the condenser with 1500 ppm of water and I need to have THF with 300 ppm
max.

Thanks,

Prof. Dr. Hamilton M. Viana
Coordenação de Engenharia de Materiais
Faculdade de Engenharia "Engº Celso Daniel"
Centro Universitário Fundação Santo André
Brazil

----- Original Message -----
From: "Jacob Zabicky" <zabicky$##$bgumail.bgu.ac.il>
To: "Lalor, Fergus" <f.lalor$##$ucc.ie>
Cc: <everybody$##$orglist.net>
Sent: Friday, October 03, 2003 12:55 PM
Subject: Re: ORGLIST:Suggestions for a laboratory experiment to replace
acetylation of ferrocene?

> Dear Fergus,
>
> If by now you haven't pocketed a couple of dozen ready-to-wear
> experiments, here is a suggestion inspired on analytical methods, which
> needs some development on your side.
>
> 1. The point of the synthesis is producing a diazo dye by the coupling
> reaction of a a phenol with a diazonium salt.
>
> 2. Possible by-products are: a) coupling at an alternative and less
> reactive site of the phenol substrate; b) partial hydrolysis of the
> diazonium salt leading to formation of a phenol that is prone to
> coupling with the diazonium ion; c) multiple couplings on the same
> substrate; d) unreacted phenol substrate or diazonium ion reagent. At
> least the main product of item 1 and the by-products of a) to c) should
> give nice bands on any chromatographic column.
>
> 3. You have a choice to go all the synthetic route, which includes as
> first step preparation of a diazonium salt solution from the
> corresponding amine (no need to isolate the product, and IMHO cheaper
> and more didactic), or buying one of the diazonium salts offered by
> reagent vendors.
>
> 4. Additional didactic points: a) the importance of the order of
> addition of reagent in an organic synthesis; should the phenol solution
> be added to the diazonium salt solution, or viceversa; I think it
> should make a considerable difference, which can be checked by part of
> the students doing it otherwise. b) The development of the reaction may
> be followed by TLC on small plates, which may also aid in planning the
> big column.
>
> 5. The main product and the by-products should be easily distinguished
> by the H and C NMR modalities.
>
> Some references:
>
> J. Itoh et.al, Chem. Abstr. 122, 16630 (1995)
> E. N. Myshak et al, J. Anal. Chem., 52, 939 (1997)
> J. S. Esteve Romero et al., Analyst, 119, 1381 (1994)
> L. Alvarez-Rodriguez et al., J. AOAC Int., 82, 937 (1999)
> O. Agraval and V.K.Gupta, Microchem. J.,62, 147 (1999)
> S. M. El-Ashry et al., Microchim. Acta, 135, 191 (2000)
> S. G. Dmitrienko et al., Chem. Anal. (Warsaw), 40, 291 (1995)
> M. Battacharjee and V. K. Gupta, Chem. Anal. (Warsaw), 39, 687 (1994)
>
> All the best,
>
> Jacob
>
>
> 3. You have
> On Friday, Oct 3, 2003, at 11:21 Asia/Jerusalem, Lalor, Fergus wrote:
>
> > Fellow organikers -
> > We have recently decided to remove the acetylation of ferrocene from
> > our
> > 3rd. Year organic practical class because of concerns about the
> > toxicity of
> > the major product, acetylferrocene. Hence we are now looking for a
> > suitable
> > replacement. The original reasons for including the ferrocene
> > experiment
> > were:
> > (1) Hands-on experience of a transition metal organometallic compound
> > which
> > does not require special conditions or apparatus..
> > (2) Experience of purification of ferrocene by vacuum sublimation.
> > (3) Experience of a Friedel-Crafts experiment on an unusual substrate
> > (4) Experience of a simple synthetic procedure where the products are
> > easily
> > separable by flash chromatography and, importantly, are all coloured
> > and
> > rtherefore eadily visible on the column.
> > (5) Ready identification of major and minor products by H and C NMR.
> >
> > Point (1) is no longer relevant as an equally relevant experiment is
> > now
> > part of their inorganic practical. Point (2) is of marginal importance
> > as
> > sublimation is hardly a main-stream purification technique. Point (3)
> > was
> > always problematical as - unfortunately - the mysteries of our
> > timetable
> > ensure that the practical takes place a whole term ahead of the
> > relevant TM
> > organometallic lectures.
> >
> > What we need as a replacement, then, is a new experiment that fits
> > criteria
> > (4) and (5). I and a colleague have done some trawling through J.
> > Chem. Ed.
> > and some lab textbooks without finding anything really appropriate. Any
> > suggestions would be most gratefully received. I should mention that
> > our
> > replacement should be capable of being completed in two 4 hr laboratory
> > sessions.
> > Regards -
> > Fergus
> >
> >
> > Dr. Fergus John Lalor
> > Senior Lecturer
> > Department of Chemistry
> > University College
> > Cork
> > Ireland.
> > Telephone: 00353-21-4902317
> > Fax: 00353-21-4274097
> > _______________________________________________
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> ***************************************************
> Prof. Jacob Zabicky
> Institutes for Applied Research
> Ben-Gurion University of the Negev
> P. O. Box 653, Beer-Sheva, 84105, Israel
>
> Phone: +972-8-6461271; Fax: +972-8-6472969
> zabicky$##$bgumail.bgu.ac.il
> http://www.bgu.ac.il/IAR/Zabicky.htm
> -------------------------------------------------
> Private:
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> Phone: +972-8-6496792
>
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