16
chemical behavior of dextrins and their properties, in agreement with the previous
results published by Schardinger. The dextrins were soluble in water but insoluble
in alcohol, ether, and chloroform. They do not reduce Fehling’s solution. To precipitate the dextrins, different solvents including benzene, toluene, xylene, bromobenzene, nitrobenzene, and petroleum ether were proposed (Pringsheim and Eissler
1913, 1914; Pringsheim 1915; Pringsheim and Lichtenstein 1916). Pringsheim confirmed that the simplest means to distinguish between the α- and β-dextrins was the
iodine reaction (Pringsheim 1922; Pringsheim and Dernikos 1922). Pringsheim was
the first to study the halogen complexes of dextrins (Pringsheim and Wolfsohn
1924; Pringsheim and Schapiro 1926). The first methylated β-dextrin was also
obtained by his group: 43.6% of degree of methylation as against 45.6% required by
theory. The compound was crystallized from ether (Pringsheim and Goldstein
1923). Several data can also be found referring to the preparation of dextrin derivatives including acetates, nitrates, and ethers (Pringsheim 1927, 1928a, b, 1931b;
Pringsheim and Meyersohn 1927; Irvine et al. 1929; Pringsheim et al. 1930, 1931a,
b; Pringsheim and Beiser 1932). However, all Pringsheim’s data are essentially of
historic interest (Samec and Blinc 1941; French 1957a; Thoma and Stewart 1965;
Caesar 1968; Szejtli 1982a; Crini 2014). From 1920 to 1925, Karrer also contributed greatly to the knowledge of the chemistry of the Schardinger dextrins (Thoma
and Stewart 1965; Caesar 1968; Szejtli 1998; Crini 2014). Karrer published several
important works on dextrins (Karrer 1920, 1921, 1922, 1923, 1925; Karrer and
Nägeli 1921a, b; Karrer et al. 1921, 1922; Karrer and Bürkin 1922). Like Schardinger
and Pringsheim, Karrer studied the crystallized dextrins with the expectation that
they would shed some light on the features of starch. In 1921, Karrer published the
first conclusions on the acetolysis of α-dextrin and β-dextrins. He demonstrated that
this reaction gave essentially the same excellent yield of maltose as starch or maltose itself gives, when treated similarly (Karrer 1921; Karrer and Nägeli 1921a, b;
Karrer et al. 1921). Karrer also investigated the interactions between dextrins and
ions such as barium, sodium, and potassium (Karrer 1922; Karrer and Bürkin 1922;
Karrer et al. 1922). In 1925, Karrer summarized the whole of his works and conclusions on dextrins in a famous comprehensive book (Karrer 1925).
Between 1911 and 1935, epoch called by Crini (2014) the “period of doubt,” other
researchers have also published interesting works on the chemistry of the Schardinger
dextrins (Biltz 1913; Biltz and Truthe 1913; Freudenberg and Ivers 1922; Miekeley
1930, 1932; Ulmann 1932, Ulmann et al. 1932; Hess et al. 1933). Miekeley (1930,
1932) published experimental data on the chemical composition of dextrins, which
complemented those of Pringsheim. In 1933, Ulmann’s group observed that the
α-dextrin-ethanol complex had two different crystal modifications which could be
interconverted. This was the first observation that a same guest may form different
crystal structures with the same dextrin (Hess et al. 1933). However, this period did
nothing to stimulate the development of Schardinger dextrins, considered as by-products of starch degradation. So, the work on cyclodextrins reported before 1935 was of
little consequence (Samec and Blinc 1941; Thoma and Stewart 1965; Caesar 1968;
Szejtli 1998; Crini 2014). This can be explained by the fact that researchers used
N. Morin-Crini et al.
chemical behavior of dextrins and their properties, in agreement with the previous
results published by Schardinger. The dextrins were soluble in water but insoluble
in alcohol, ether, and chloroform. They do not reduce Fehling’s solution. To precipitate the dextrins, different solvents including benzene, toluene, xylene, bromobenzene, nitrobenzene, and petroleum ether were proposed (Pringsheim and Eissler
1913, 1914; Pringsheim 1915; Pringsheim and Lichtenstein 1916). Pringsheim confirmed that the simplest means to distinguish between the α- and β-dextrins was the
iodine reaction (Pringsheim 1922; Pringsheim and Dernikos 1922). Pringsheim was
the first to study the halogen complexes of dextrins (Pringsheim and Wolfsohn
1924; Pringsheim and Schapiro 1926). The first methylated β-dextrin was also
obtained by his group: 43.6% of degree of methylation as against 45.6% required by
theory. The compound was crystallized from ether (Pringsheim and Goldstein
1923). Several data can also be found referring to the preparation of dextrin derivatives including acetates, nitrates, and ethers (Pringsheim 1927, 1928a, b, 1931b;
Pringsheim and Meyersohn 1927; Irvine et al. 1929; Pringsheim et al. 1930, 1931a,
b; Pringsheim and Beiser 1932). However, all Pringsheim’s data are essentially of
historic interest (Samec and Blinc 1941; French 1957a; Thoma and Stewart 1965;
Caesar 1968; Szejtli 1982a; Crini 2014). From 1920 to 1925, Karrer also contributed greatly to the knowledge of the chemistry of the Schardinger dextrins (Thoma
and Stewart 1965; Caesar 1968; Szejtli 1998; Crini 2014). Karrer published several
important works on dextrins (Karrer 1920, 1921, 1922, 1923, 1925; Karrer and
Nägeli 1921a, b; Karrer et al. 1921, 1922; Karrer and Bürkin 1922). Like Schardinger
and Pringsheim, Karrer studied the crystallized dextrins with the expectation that
they would shed some light on the features of starch. In 1921, Karrer published the
first conclusions on the acetolysis of α-dextrin and β-dextrins. He demonstrated that
this reaction gave essentially the same excellent yield of maltose as starch or maltose itself gives, when treated similarly (Karrer 1921; Karrer and Nägeli 1921a, b;
Karrer et al. 1921). Karrer also investigated the interactions between dextrins and
ions such as barium, sodium, and potassium (Karrer 1922; Karrer and Bürkin 1922;
Karrer et al. 1922). In 1925, Karrer summarized the whole of his works and conclusions on dextrins in a famous comprehensive book (Karrer 1925).
Between 1911 and 1935, epoch called by Crini (2014) the “period of doubt,” other
researchers have also published interesting works on the chemistry of the Schardinger
dextrins (Biltz 1913; Biltz and Truthe 1913; Freudenberg and Ivers 1922; Miekeley
1930, 1932; Ulmann 1932, Ulmann et al. 1932; Hess et al. 1933). Miekeley (1930,
1932) published experimental data on the chemical composition of dextrins, which
complemented those of Pringsheim. In 1933, Ulmann’s group observed that the
α-dextrin-ethanol complex had two different crystal modifications which could be
interconverted. This was the first observation that a same guest may form different
crystal structures with the same dextrin (Hess et al. 1933). However, this period did
nothing to stimulate the development of Schardinger dextrins, considered as by-products of starch degradation. So, the work on cyclodextrins reported before 1935 was of
little consequence (Samec and Blinc 1941; Thoma and Stewart 1965; Caesar 1968;
Szejtli 1998; Crini 2014). This can be explained by the fact that researchers used
N. Morin-Crini et al.