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Technique Of Organic Chemistry Vol. VI

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The advantages of microchemical methods are the saving of time, labor,
and materials. Much of the work on vitamins, hormones, and other
natural products would not have been possible had more than fractions of a
gram been required for the elucidation of structure of these compounds. n
addition, through the application of small scale experimentation it is often
possible to complete the preparation of several compounds in the time re-
quired for one synthesis by macromethods
Elementary microanalysis offers a classic example of the advantages of
work on a micro scale. In 1909-1910, Pregl isolated from gallstones an
extremely small quantity of an apparently new organie compound, and it
was important to determine the carbon and hydrogen contents quantita-
Thus a decision had to be arrived at either to continue the investi-
tively.
gation with exceptionally large quantities of the original material or so to
modify the quantitative analysis of organic substances that it should be
possible to obtain correct analytical figures with quantities of material hith-
erto unheard of, so that a formula could be determined with certainty.'' 1
The micromethods of quantitative organic analysis developed by Pregl
gained wide acceptance in the decade following World War I. In the
United States, between 1920 and 1930, a few colleges and universities added
microanalytical laboratories to their chemistry departments. In most
instances, the microanalytical laboratory remained the domain of the
"Organic Division" and performed routine elementary analyses for research
workers in organic chemistry. However, within the past few years there
has been a definite trend, under the leadership of analytical and physical
chemists, toward offering instruction in the microdetermination both of
elements and of functional groups of organie compounds.
The development and use of microchemical preparative methods has
lagged behind the analytical procedures. The cause is not entirely the re-
sult of the "dead hand of tradition,"' although it is true that a beginner
brought up to consider that the orthodox quantity of an organic prepara-
tion is 25-100 grams, will probably attempt to synthesize organic com-pounds in similar quantities. Inexperienced workers, with the exception
of those under expert tutelage, obtained discouraging results with the early
micromethods which were usually designed for the preparation of milli-
gram quantities. This gave rise eventually to a shift in the quantities used
from a few milligrams to several hundred, or even to a few grams, and
created a new scale between micro and macro. In the United States this
new scale has been designated as semimicro, and has led to the development
and increasing use of micropreparative methods.
The other reason for the lag in the development of preparative organic
microchemistry is that, except in the case of biochemical research, there
was until recently no impelling reason to reduce the quantities of reactants
in the usual synthetic methods. However, the increased amount of ex-
ploratory work in industrial research has led to a wider use of micropre-
parative methods; organic syntheses with isotopes have rendered the
development of micropreparative methods inescapable because of the
scarcity, cost, and dangerous nature of most isotopes.

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252/VI

547 TEC t

Perpustakaan PPKS Medan Lt. 1 (547)

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Detail Information

Series Title

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Call Number

547 TEC t

Publisher

New York/London : Interscience Publishers Inc.., 1954

Collation

xxiii, 628 hal.: ill; 23 cm

Language

English

ISBN/ISSN

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Classification

547

Content Type

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Media Type

-

Carrier Type

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Edition

VI

Subject(s)

Technology

Specific Detail Info

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Statement of Responsibility

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