Geoscience Reference
In-Depth Information
form biomolecules through streckers synthesis under hydrothermal conditions, the
availability and concentration of starting components limit the efficiency and produc-
tivity of strecker reactions. Some representative reactions for strecker synthesis are
given below
[102]
:
RCHO
NH
3
1
HCN
RCH
ð
NH
2
Þ
CN
H
2
O
1
5
1
aldehyde
=
ketone
amino nitrile
RCH
ð
NH
2
Þ
CN
H
2
O
RCH
ð
NH
2
Þ
CO
ð
NH
2
Þ
1
5
amino nitrile
amino amide
RCHO
HCN
H
2
O
RCH
ð
NH
2
Þ
COOH
1
1
5
aldehyde
=
ketone
amino acid
There are several reports on the laboratory hydrothermal synthesis of amino
acids to justify the origin of life on the earth. It is appropriate to mention that the
organic synthesis on the whole is not new and, in fact, it began in the previous cen-
tury. However, the organic synthesis under hydrothermal conditions with reference
to the origin of life began in a systematic way only during 1980s, after the discov-
ery of hydrothermal activity in the deep sea on a Galapagos spreading rich in ther-
mophile organisms (
Figure 1.5a and b
) during 1977. The reader can get additional
information from the works of Fox and Windsor
[103]
, Marshall
[104]
, Shock
[105,106]
, and Hennet et al.
[107]
. These workers have synthesized amino acids in
a temperature range of 150
275
C from aqueous solutions containing KCN, NH
3
,
HCHO, CO
2
,H
2
,O
2
, NaCN, NH
4
HCO
3
. Miller
[108]
, and Shock in Ref.
[102]
,
have shown that the autotrophic synthesis of all 20 protein-forming amino acids
was energetically favored in hot (100
C), moderately reduced, submarine hydro-
thermal solutions relative to the synthesis in cold (18
C), oxidized, surface seawa-
ter
[108]
. Although the above studies do not support the challenge raised by several
others over the life in submarine hydrothermal ecosystems, these studies definitely
have set a new trend in hydrothermal research.
This field of research is growing very fast and a large number of publications
are coming on diversified aspects of submarine hydrothermal ecosystems. The
reader can refer
to some of
the most
important reviews for
further studies
[100,108,109]
(
Figure 1.7
).
1.8 Hydrothermal Crystal Growth and Materials Processing
After the successful application of the hydrothermal technique in hydrometallurgy
in the previous century, the other important application of this method began with
the artificial production of bulk single crystals of quartz and also with the synthesis
of zeolites during late 1930s and 1940s. The hydrothermal method of crystal growth
has several advantages. It is very important for its technological efficiency in
