From: Hamilton M. Viana (hmviana$##$uol.com.br)
Date: Fri Oct 10 2003 - 07:19:27 EDT
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
Prof. Dr. Hamilton M. Viana
Coordenação de Engenharia de Materiais
Faculdade de Engenharia "Engº Celso Daniel"
Centro Universitário Fundação Santo André
----- Original Message -----
From: "Jacob Zabicky" <zabicky$##$bgumail.bgu.ac.il>
To: "Lalor, Fergus" <f.lalor$##$ucc.ie>
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,
> 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
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