Sonderdruck aus der Zeitschrift "die starke - starch"
Internationale Zeitschrift fUr die Erforschung, Verarbeitung und Verwendung von
Kohlenhydraten und deren Derivaten
International Journal for Research, Processing, and Use of Carbohydrates and
23. Jahrgang . Heft 2 . Seite 42-45
Verlag Chemie GmbH., Weinheim/Bergstr.
P u r ~ h a s e d by U. S. Dept. of
Agnculture for Official Use
Chemical Process for Making Dialdehyde Starch
By T. A. McGuire and C. L. Mehltretter, Peoria, Illinois (USA)
A practical, strictly chemical process has been developed for the periodic acid oxidation of stardJ
to dialdehyde stardJ. In the procedure spent oxidant is convel'ted by alkaline hypochlorite to
insoluble sodium paraperiodate, which is reco'<Jered in high yield for recycling. The process is
suitable for small-scale production of dialdehyde starches of variollS carbonyl contents.
(Zusammenfasslmg siehe Seite 44; Resume d la page 44)
Dialdehyde starch (DAS) is manufactured on a large scale
in the United States  and in Japan  by the periodic
acid oxidation of corn starch. In these processes electrolytic
regeneration of the spent oxidant [3, 4] is utilized and a
large capital outlay for specialized equipment is required
. Occasionally for various commercial applications, small
amounts of periodic acid-oxidized polysaccharides having
a wide range of carbonyl contents are required [5, 6]. In
such cases the expense of costly electrolytic equipment is
not warranted, and it would be desirable to have a strictly
chemical process for converting the iodic acid in spent
liquors to periodic acid for reuse. Simple procedures are
known for preparing periodic acid in high yield from iodic
acid  as shown in the equations below.
HI03+ 5 NaOH + Cl2-- Na3H2IOij + 2 NaCI + 2Hp
2 Na3H2IOij + 3 H2S04-- 2 HI04+ 3 Na2S04+ 4 Hp
Optimum conditions for the periodic acid oxidation of
starch to DAS [3, 8J have also been previously established.
Detailed data are lacking, however, on product and spent
oxidant recovery for these reactions.
This paper describes an efficient, practical method to make
DAS having a carbonyl content of at least 97 %
The process is based upon a materials balance study of five
consecutive small-scale oxidations of starch utilizing peri-
odic acid regenerated chemically from successive spent
liquors. Carbonyl contents of DAS of a fraction of a per-
cent and up may be prepared by using the equivalent
amount of periodic acid in the oxidation. The simplicity of
the process should permit scale-up with little difficulty.
Preparation of Sodium Paraperiodate
Iodine (100 g) was oxidized to sodium iodate with 125 g of
sodium chlorate according to the procedure of Willard .
The reaction required about 3 h for completion at a temper-
ature of 45 - 50 DC. The sodium iodate in solution was then
converted to sodium paraperiodate as follows: To the stirred
sodium iodate solution in a 2-liter beaker was added 200 ml
of water followed by 140 g of sodium hydroxide pellets.
The hot solution was then maintained at 90-95 DC in a
steam bath and 75 g of chlorine passed into the mixture
during 1 h. The reaction mixture was then adjusted to
pH 11.5 by addition of 50 WI' percent solution of sodium
hydroxide to complete the conversion to insoluble sodium
paraperiodate. After cooling the reaction mixture to room
temperature the product was filtered by suction on a fritted
glass funnel of medium porosity and washed once on the
filter with cold water. The crude sodium paraperiodate was
dried at 110 DC and weighed 223.4 g (theory, 231.6 g). Cal-
culated weight of Na3H2IOij (from periodate analysis) in
223.4 g of product was 225.1 g and indicated the presence
of some Na2H3IOij' Yield of recovered product was there-
fore 97 % of theory.
Periodic Acid Oxidation of Starch to Dialdehyde Starch
o ~ ~
Wash Numbers -----0.
Figure 1. HI03and HI04in successive dialdehyde starch washes
calculated as HI04•
A stirred slurry of 136.2 g of the sodium paraperiodate
(equivalent to 89.6 g HI04by analysis) in 400 ml of water
in a I-liter beaker was treated with about 75 ml of 50 WI'
percent of sulfuric acid added in portions to obtain a pH
of 1.5. The beaker was placed in a circulating water bath
for temperature control and the solution cooled to about
20 DC before the reaction with starch. Unmodified corn
starch, 77.0 g (68.8 g; dry basis) slurried in 100 ml of water,
was added to the periodic acid solution and the temperature
of the reaction was maintained at about 32 DC with the
circulating water bath. The reaction mixture was stirred for
4 h at 32 DC ± 2 DC. The dialdehyde starch that was pro-
duced was then filtered by suction on a fritted glass funnel
of medium porosity, washed five times by slurrying in
200 ml of water each time, and filtering. Removal of spent
oxidant was followed by analysis of the individual washes.
The colorless filtrate from the oxidized starch was also
analyzed for iodic acid and unreacted periodic acid. fig-
ure 1 illustrates the amount of iodic and unreacted periodic
1 " 5 ~
~ 0 7 5
~ 0 . 2 5
gHI03= ml Na2SP3 X normality X 0.02932
gHI04= (5 ml arsenite X normality - ml 12X normality)
To a solution contammg about 0.03 g of iodic acid neu-
tralized with alkali and diluted to 15 ml with water in a
125-ml Erlenmeyer flask is added 1 ml of ethylene glycol.
The solution is acidified to pH 3.5
at least 15 min to reduce any periodate present to iodate.
Next 3 ml of 0.5 N sulfuric acid and 2 ml of basic potassium
iodide solution are added and after standing for 2 min the
iodine liberated is titrated with 0.1 N sodium thiosulfate
solution using starch indicator.
5 and allowed to stand
To determine the unreacted periodic acid and the iodic acid
in spent oxidation liquors and the purity of crude sodium
paraperiodate, the method of Fleury and Lange [9J was
modified. To a solution containing about 0.03 g of periodic
acid neutralized with alkali in a 125-ml Erlenmeyer flask,
is added 10 ml of a saturated solution of sodium bicarbonate
and then immediately 5 ml of 0.1 N sodium arsenite solution
and 1 ml of a 20 %
basic potassium iodide solution. The
mixture is allowed to stand for 15 min. Excess arsenite is
titrated with 0.1 N iodine solution using starch indicator.
Carbonyl Content of Dialdehyde Starch
Analyses for carbonyl content of DAS were performed by a
modification of the spectrophotometric method of Wise and
Mehltretter . The p-nitrophenylhydrazone precipitate
obtained in the original procedure is dissolved in warm ethy-
lene glycol monomethyl ether instead of hot 95 %
The solution is transferred to a 200-ml volumetric flask and
adjusted to volume with the new solvent before absorbance
Table 1.Dilaldehyde Starch and Oxidant Recovery from Five Consecutive Reactions.
Ofo of theory
010 of theory
1 Dry basis.
2 HI04equivalent calculated from the periodate found by ana-
lysis of the crude Na3H2IOo•
acids removed from the product in each wash, calculated
as periodic acid for comparison with the periodic acid
equivalent of 89.6 g originally used.
The white dialdehyde starch was dried in a forced draft
oven at 60 DC overnight and weighed 67.4 g (dry basis).
Analysis for carbonyl content showed that the product was
at least 97010 dialdehyde starch.
Five consecutive oxidations of starch were made in which
periodic acid regenerated from the previous run was used;
the yields and analyses of the dialdehyde starches are given
in Table 1.
Conversion of Spent Oxidant to Sodium Paraperiodate
Washings from the dialdehyde starch product were com-
bined (1,000 ml) and concentrated in a vacuum rotary
evaporator to 200 ml and added to the original filtrate
(900 ml) of the product. The spent oxidant solution after
analysis for iodic acid and unreacted periodic acid present
was placed in a 2-liter beaker and adjusted to pH 7 with
50 wt percent sodium hydroxide. Sodium hydroxide pellets
(83.7 g) were then added gradually with stirring. The rest
of the procedure used for the initial preparation of sodium
paraperiodate was then followed; 45 g of chlorine was
added during 40 min of reaction at 90-95 0c. The dried
crude sodium paraperiodate weighed 135.9 g. It assayed to
be equivalent to 88.4 g periodic acid.
Periodic acid recovery data for the five starch oxidations
are recorded in Table 1. After the first oxidation, 30/0
makeup of sodium paraperiodate was added because of the
nearly 3 0/0 loss of oxidant in the recovery step.
Dialdehyde starch having a carbonyl content of at least
97010 of the theoretical was readily prepared in nearly
quantitative yield by this chemical process. Recycling of the
regenerated spent oxidant after addition of 3010 sodium
paraperiodate makeup was successful for five starch oxida-
tion reactions carried out consecutively. Spent oxidant was
collected quantitatively and its oxidation by alkaline hypo-
chlorite permitted 97010 or better recovery of the iodic and
unreacted periodic acids present, as insoluble sodium para-
periodate. By this means also such impurities in corn starch
as fatty acids and protein that may have leached into the
3 HI04equivalent to HI03and unreacted HI04found by ana-
lysis of the combined filtrate and washings of DAS.
spent liquors were removed from the crude sodium para-
periodate during its isolation by filtration and therefore did
not build up in the successive reactions. Conversion of the
insoluble crude sodium paraperiodate to periodic acid in
aqueous solution by addition of sulfuric acid also produced
sodium sulfate in solution. The presence of this salt aided
in the reduction of swelling of the starch granules during
oxidation and thus allowed more rapid filtration of the
DAS product. The chief advantage of the chemical process,
however, is that it avoids the use of expensive electrolytic
equipment for regeneration of spent oxidant for recycling
in the process.
Chemisches Verfahren zur Herstellung von Dialdehydstarke.
Fiir die Perjodsaureoxydation von Starke Zli Dialdehydstarke
wurde ein praktisches, streng chemisches Verfahren ent·wickelt. Bei
diesem Prozej) wird das zugesetzte Oxydationsmittel durch alkali-
sches Hypochlorit in Imlosliches Natrium-Paraperjodat umgewan-
delt, welches in hoher Alisbelite fiir die Riickjiilmmg wieder-
gewonnen wird. Das Verfahren ist fiir die Produktion von Dial-
dehydstarken mit verschiedenen Carbonylgehalten in kleinerem
Procedes chimiques pour la fabrication de I'amidon dialdehyde.
Un procede pratique, strictement chimique a he developpe pour
l'oxydation pf:riodique de l'amidon en amidon dialdehyde. Au
cours de ce procesSl!s l'agent oxydant utilise est converti par
l'JrypochlO>'ite alcalin en paraphiodate de sodium insoluble. Ce
procede est approprie pOlir Ime production d'amidon dialdehyde a
petite echelle d'lme teneur en groupements carbonyl variable.
 Miles Laboratories, Inc., Elkhart, Indiana, USA.
 The Japan Cadit Co., LTD., 2470 Handa, Shibukawa-shi,
Gunma-ken, 377 Japan.
 Pfeifel', V. F., V. E. Sohns, H. F. Conway, E. B. Lancaster,
S. Dabic, and E. L. Griffin, Jr.: Ind. Eng. Chern. 52 (1960),
 Ramaswamy, R., M. S. Venkatachalapathy, and V. K. Udupa:
Indian J. Techno!. 1 (1963), 115.
 Yelland, W. E. C.: United States Patent 2,606,188 (1949).
 Cousins, E. R., A. L. Bullock, C. H. Mack, and S. P. Rowland:
Text. Res. J. 34 (1964), 953.
 Willard, H. H.: In "Inorganic Syntheses", ed. by H. S. Booth.
McGraw Hill Book Co., Inc., New York (1939), vol. 1,
 Fleche, G.: Starke 20 (1968), 50.
 Fleury, P. P., and ]. Lange: J. Pharm. Chern. 17 (1933), 107.
 'Vise, C. S., and C. L. Mehltretter: Anal. Chern. 30 (1958),
Address of authors: T. A. McGuire, M. S., and C. L. Mehltretter,
Ph. D., Cereal Products Laboratory, Northern Regional Research
Laboratory"", Peoria, Illinois, 61604 (USA).
". This ist a laboratory of the Northern Utilization Research and
Development Division, Agricultural Research Service, U. S.
Department of Agriculture.
(Received: November 5, 1970)