RE: ORGLIST: Overpressure valves

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From: Ismail F (F.M.Ismail$##$livjm.ac.uk)
Date: Mon Jan 21 2002 - 13:04:13 EST

Dear Dr. Engel,

You can use a variety of systems and can replace mercury with a viscous
hydrocarbon oil. One cheap solution is to use motor car oil or, more
expensively, a silicone oil. If use a double vacuum manifold as described
in:

Leonard J., Lygo B., Proctor G., Advanced Practical Organic Chemistry, 3rd
ed. 1998. Stanley Thorne Publishers.

Available from Aldrich (e.g. z17,443-2.

An additional tap mounted into the middle of the manifold allows one side of
this system to be under slightly greater pressure than the other. The flow
rate can be adjusted through the manifold by manipulating the gas flow rate
using an oil filled bubbler before and after the vacuum line. Normally I use
a one 500 cm tall bubbler with an in-built trap to prevent ingress of the
oil into the reaction vessel.
Using flexible tubes (e.g. Chem-flex) equipped with needles allows
connection of the line and flask through a white rubber septum (suba seals
available from the Aldrich Chemical Company e.g. Z10,074-9)and, therefore,
safely pressurise the flask. The seal can be kept in place using and a wrap
it ties (Z 10,595-3). An additional needle inserted into the septum relieves
pressure (and toxic volatile substance, if any) back to the line.
alternatively, you can also use the Aldrich Firestone Valve (z 10,361-6).

http://www.staff.livjm.ac.uk/pacfisma/

Dr. Fyaz M.D. Ismail

Senior Lecturer in Medicinal Chemistry
The Medicinal Chemistry Research Group
The School of Pharmacy and Chemistry
Liverpool John Moores University
Room 221C James Parsons Building
Byrom Street
Liverpool L3 3AF
f.m.ismail$##$livjm.ac.uk
Telephone: +44 (0)151 231 2231.

>-----Original Message-----
>From: Richard Prankerd [mailto:richard.prankerd$##$vcp.monash.edu.au]
>Sent: 20 January 2002 23:30
>To: Multiple recipients of list orglist
>Subject: Re: ORGLIST: Overpressure valves
>
>
>Michael:
>
>If the gas space in the system is small, then you can use a
>balloon filled with
>the inert gas
>
>Richard
>
>Michael Engel wrote:
>
>> Hello,
>> I am an organic chemist and, until some years ago, I used
>mercury valves as
>> an overpressure valve when doing synthesis under an inert atmosphere.
>> During the last years, I didn't have to use such overpressure valves.
>> Now I am back and I want/have to to use some other types of valves.
>> What do use in your country, are Hg valves still in use ?
>> Thanks for any advice.
>> Best wishes
>> Michael Engel
>> (Japan)
>>
>> __________________
>>
>> ORGLIST - Organic Chemistry Mailing List
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>
>--
>Richard J. Prankerd, PhD
>Senior Lecturer
>Victorian College of Pharmacy, Monash University
>381 Royal Pde., Parkville VIC 3052
>
>Phone: INT+613-9903-9003
>Phax: INT+613-9903-9583
>
>Drugs need to be designed with delivery components in mind -
>Takeru Higuchi
>
>
>__________________
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