IMPERIAL COLLEGE OF SCIENCE AND TECHNOLOGY

(UNIVERSITY OF LONDON)

ROYAL COLLEGE OF SCIENCE

DEPARTMENT OF CHEMISTRY IMPERIAL INSTITUTE ROAD,
LONDON : - S.W.7.
Telephone: KENSINGTON 5111

JAK /EMS 9th October 1958

Professor J. Lederberg,
Department of Genetics,
University of Wisconsin,
Maddison 6,

Wisconsin, U.S.A.

Dear Professor Lederberg,

Thank you for your letter of 19th September and your
kind remarks about my small monograph.

_ I must apologize for the delay in replying, occasioned
partly by the impact of our new term and partly by the difficulty
of finding an adequate answer to your enquiry.

The faet is that I do not know of any comprehensive

review of preparative methods for the condensation type of ion-
exchange resins, The newest approach, as far as I am aware,
is an appendix to the thesis of one of my research students
(A. O, Jakubovic, Fh.D. thesis, University of London, 1958) in
which he has collected and classified some 255 references,
mostly patents, to the preparation of ion-exchange resins,
I have written to Dr. Jakubovic, but unfortunately he has no
spare copy of this report. It seems hardly necessary to go
to the lengths of photostatting 29 pages of typescript, so I
have extracted, on the enclosed sheet, a few examples.

OL (wInay 24¢,/74

Very few resins having amphoteric properties have
been described, for the simple reason that they cannot be readily
regenerated. As both cation- and anion-exchangers can be
prepared by condensation with formaldehyde, an obvious possibility
is to use a mixture of, say, salicylic acid and m-phenylene
diamine with phenol and formaldehyde. The number of possibilities
is enormous, To narrow down the search, you should indicate
whether you need carboxyl or sulphonate acid groups and amino,
substituted amino or quaternary ammonium basic groups; whether
aromatic or aliphatic; whether high capacity or low is your aim?
whether the structure must be well-defined, or whether cheapness
is of primary interest. The cheapest amphoteric resin, after
all, is wool, or some other protein rendered insoluble by cross-
linking with formaldehyde. In any case, why restrict the enquiry
to condensation resins? Their structure is so little understood
that almost all fundamental work is being done nowadays with
polymerization resins, where the molecular structure can be pretty
well “tailor-made” to requirements.

There have, in fact, been numerous papers on synthetic,
linear amphoteric polyelectrolytes, and it would be a simple matter
to modify the preparation so as to build in a controlled degree of
cross-linking and so produce an amphoteric resin. There is no
one who knows more of this type of material than Dr. H. P. Gregor,
Department of Chemistry, Polytechnic Institute of Brookly, Brooklyn,
New Yorxk. (incidentally, he gives a useful review of some recent
preparative methods in Am, Review Of Physical Chem, 1957 8, 463).
May I suggest that you put your enquiry to him, specifying as closely
as possible the requirements to be met?

Yours sincerely, fh i
J

. A. Kitchener.