Preparation of alkyl glycosides

The preparation of alkyl glycosides by reaction of aqueous glycoses having a water content of 10-80% by weight with aliphatic primary alcohols having from 5 to 30 C atoms is described, in which PA1 (a) the alcohols and the glycoses are employed in a molar ratio of 2:1 to 10:1, PA1 (b) 0.1-5% by weight, based on the amount of the glycoses employed, of the acidic form of an anionic surfactant is used as the acidic catalyst having emulsifying properties, PA1 (c) 1-30% by weight, based on the amount of the glycoses employed, of alkyl glycosides is used as a further emulsifier, PA1 (d) the aqueous glycose is preheated to 50.degree.-90.degree. C. and the preheated aqueous solution of the glycose is metered with effective mixing into the reaction mixture of alcohol, acidic catalyst and emulsifier in such a manner that an emulsion is formed, PA1 (e) the reaction is carried out at from 100.degree. to 150.degree. C. and from 10 to 100 mbar, the water introduced into the reaction mixture and the water formed by the reaction being continuously removed by distillation, PA1 (f) after the reaction has ended, the acidic catalyst is neutralized by addition of a base such that the resulting mixture has a pH of 8-10, then PA1 (g) the excess alcohol is removed by distillation at from 0.01 to 10 mbar down to a residual content of less than 5% by weight, based on the amount of alkyl glycoside present, and PA1 (h) the reaction mixture is bleached at pH 8-10 after conversion into an aqueous paste having a content of from 30 to 70% by weight of alkyl glycoside using a compound eliminating active oxygen.

PREATION OF ALKYL GLYCOSIDES 
The present invention relates to an improved process for preparing alkyl 
glycosides by reaction of aqueous glycoses having a water content of 
10-80% by weight with aliphatic primary alcohols having from 8 to 30 C 
atoms. 
Surface-active alkyl glycosides, which are mainly used in the detergent and 
cleaner sector, have been known for a long time and are prepared on the 
industrial scale by two different types of process. Either the long-chain 
alcohol component is directly linked to the sugar component with 
elimination of water by direct synthesis or a short-chain alkyl glycoside 
is first prepared as intermediate by the transacetalization method and is 
then reacted in a second step by transacetalization with long-chain 
alcohols to give the surface-active alkyl glycoside. However, the 
transacetalization method has a number of disadvantages in principle 
compared with direct synthesis, such as the additional use of a 
short-chain alcohol, a poorer space-time yield or the formation of 
relatively complex product mixtures. 
EP-A 0,252,241 may be mentioned as an example of the transacetalization 
method. According to this, butyl oligoglycosides are prepared by 
acid-catalyzed reaction, for example using sulfuric acid or 
p-toluenesulfonic acid, of aqueous saccharide syrups with the addition of 
butyl oligosaccharides. The short-chain butyl glycosides can then be 
subjected to a transacetalization to give longer-chain alkyl glycosides. 
In EP-A 0,362,671, and also in the references cited below, a direct 
synthesis of longer-chain alkyl glycosides is described. This 
specification recommends the use of acidic catalysts such as sulfuric 
acid, phosphoric acid or aliphatic or aromatic sulfonic acids for the 
acetalization reaction. The glycoses used for the reaction, such as 
glucose, should be as anhydrous as possible. The reaction is carried out, 
for example, by adding a suspension of the glycose in a fatty alcohol 
continuously to a mixture of acidic catalyst and fatty alcohol and at the 
same time removing the resulting water of reaction by distillation under 
reduced pressure. 
A process is described in EP-A 0,096,917 in which a monosaccharide, such as 
glucose, suspended in a fatty alcohol is added continuously or in portions 
to a mixture of fatty alcohol and an acidic catalyst such as sulfuric acid 
or toluenesulfonic acid at from 80.degree. to 150.degree. C. in such a 
manner that no more than 10% of unreacted monosaccharide is present in the 
reaction mixture. Anhydrous glucose of a specific particle size is 
employed. 
As the acidic catalyst for the direct synthesis of alkyl glycosides, EP-B 
0,132,043 recommends the acid form of an anionic surfactant, by whose use 
instead of customary catalysts, such as sulfuric acid or p-toluenesulfonic 
acid, it is intended to improve the color quality of the product and to 
reduce the content of undesired polysaccharides in the final product. In 
the process of this reference only a small excess of fatty alcohol is 
employed, preferably 2 mol of fatty alcohol per mole of glucose, which is 
used in its anhydrous form, and during the neutralization of the acidic 
catalyst with a base a pH of from 6.6 to 7 is maintained. 
WO-A-90/07516 and DE-A 3,927,919 also describe the use of surface-active 
acidic catalysts of this type, dinonylnaphthalenesulfonic acid or 
sulfosuccinic acid, to obtain an alkyl glycoside having a paler color and 
a low content of polysaccharides. 
US-A-4,721,780 describes a process for preparing alkyl polyglucosides in 
which aqueous monosaccharide solutions are reacted with monohydric C.sub.2 
- to C.sub.6 -aliphatic alcohols in a homogeneous aqueous phase in the 
presence of acidic catalysts at from 60.degree. to 200.degree. C. and 
water is removed from the reaction mixture in such a manner that a 
separate phase of an aqueous monosaccharide solution is not formed. 
A corresponding process is disclosed in U.S. Pat. No. 4,996,306 for the 
preparation of C.sub.7 - to C.sub.30 -alkyl polyglucosides, in which 
aqueous mono- or oligosaccharide solutions are reacted with C.sub.7 - to 
C.sub.30 -alcohols in a homogeneous, single-phase aqueous reaction medium. 
In this process too, the formation of a separate phase which consists of 
an aqueous saccharide solution should be avoided. The examples of U.S. 
Pat. No. 4,996,306 however relate only to the acid-catalyzed reaction of 
aqueous saccharide solutions with n-propanol, n-butanol or mixtures of 
n-butanol and methanol, methanol being employed to improve the miscibility 
of the reactants in order carry out the reaction in the homogeneous phase. 
The alkyl glycosides-prepared by the processes known from the prior art, 
however, still have a number of disadvantages. As a rule, they are still 
too highly colored and often have a hydrophilic/hydrophobic ratio which is 
too unfavorable. It is in particular desired in the case of alkyl 
glycosides to shift the hydrophilic/hydrophobic ratio in favor of the 
hydrophobic moiety. This is best achieved by a controlled synthesis of 
alkyl monoglycosides and avoidance of the alkyl oligo- and polyglycosides. 
The higher the content of the alkyl monoglycosides, naturally the more 
hydrophobic the behavior of the product. 
Additionally, a further simplification of the preparation process for alkyl 
glycosides is desired. The preparation process, even on the industrial 
scale, should be highly efficient, problem-free to carry out and 
economical. In particular, it should be possible to use easily accessible 
feedstocks. 
It is an object of the present invention to provide an improved preparation 
process for alkyl glycosides which yields products having improved 
properties and is efficient, problem-free to carry out and economical. 
We have found that this object is achieved using a process for preparing 
alkyl glycosides by reaction of aqueous glycoses having a water content of 
10-80% by weight with aliphatic primary alcohols having from 8 to 30 C 
atoms, if 
(a) the alcohols and the glycoses are employed in a molar ratio of 
2:1-10:1, 
(b) 0.1-5% by weight, based on the amount of the glycoses employed, of the 
acidic form of an anionic surfactant is used as the acidic catalyst having 
emulsifying properties, 
(c) 1-30% by weight, based on the amount of the glycoses employed, of alkyl 
glycosides is used as a further emulsifier, 
(d) the aqueous glycose is preheated to 50-90.degree. C. and the preheated 
aqueous solution of the glycose is metered with effective mixing into the 
reaction mixture of alcohol, acidic catalyst and emulsifier in such a 
manner that an emulsion is formed, 
(e) the reaction is carried out in emulsion at from 100.degree. to 
150.degree. C. and from 10 to 100 mbar, the water introduced into the 
reaction mixture and the water formed by the reaction being continuously 
removed by distillation, 
(f) after the reaction has ended, the acidic catalyst is neutralized by 
addition of a base such that the resulting mixture has a pH of 8-10, then 
(g) the excess alcohol is removed by distillation at from 0.01 to 10 mbar 
down to a residual content of less than 5% by weight, based on the amount 
of alkyl glycoside present, and 
(h) the reaction mixture is bleached at pH 8-10 after conversion into an 
aqueous paste having a content of 30-70% by weight of alkyl glycoside 
using a compound eliminating active oxygen. 
In the following, alkyl glycosides are understood as meaning the reaction 
products of sugars and aliphatic alcohols, suitable sugar components in 
the following being aldoses and ketoses designated as glycoses, for 
example glucose, fructose, mannose, galactose, talose, gulose, allose, 
altrose, idose, arabinose, xylose, lyxose or ribose. Because of the better 
reactivity, the aldoses are preferably used. Among the aldoses, glucose is 
particularly suitable because of its easy accessibility and availability 
in industrial quantities. The alkyl glycosides which are preferably 
prepared by the process of the invention are therefore the alkyl 
glucosides. 
The term alkyl in alkyl glycoside includes the radical of a primary 
aliphatic alcohol of chain length C.sub.8 to C.sub.30, in particular of a 
fatty alcohol obtainable from natural fats. The terms alkyl 
oligoglycoside, alkyl polyglycoside, alkyl oligosaccharide or alkyl 
polysaccharide relate to those alkylated glycoses in which an alkyl 
radical is bonded to more than one glycose radical, i.e. to a poly- or 
oligosaccharide radical, in the form of the acetal. These terms are 
regarded as synonymous with one another. Accordingly, an alkyl 
monoglycoside is the acetal of a monosaccharide. Since mixtures are in 
general obtained in the acid-catalyzed reaction of sugars and aliphatic 
alcohols, in the following both alkyl monoglycosides and alkyl 
poly(oligo)glycosides and in particular mixtures thereof, including 
possible secondary components such as, for example, fructosides, are 
understood under the term alkyl glycoside. 
In the process of the invention it has been found that in the synthesis of 
long-chain alkyl glycosides by the direct procedure anhydrous glucose, 
which on the one hand can only be prepared in a complicated manner and on 
the other hand is difficult to handle, or starch, which has to be 
subjected to a degradation reaction beforehand and therefore requires 
cosolvents, no longer has to be employed, but aqueous glucose (dextrose 
syrup) can be used. An aqueous glucose solution of this type is obtained 
in the enzymatic or acidic hydrolysis of starch, for example potato, corn 
or wheat starch, and may contain a variable content of free glucose. Thus, 
the amount of free, monomeric glucose should be at least 50% by weight, 
based on the solids content. An aqueous glucose solution containing at 
least 80% by weight of monomeric glucose, particularly preferably a 
content of more than 90% by weight of monomeric glucose, is preferred. In 
addition to the monomeric glucose, higher oligomeric and polymeric sugar 
components can also be present, depending on how they are formed in the 
hydrolysis of starch. 
In addition to the aqueous glucose, other glycoses, for example fructose, 
mannose, galactose, talose, gulose, allose, altrose, idose, arabinose, 
xylose, lyxose and ribose can also be employed in their aqueous form at 
the given monomer contents. Glycose mixtures, oligosaccharides, for 
example maltose, lactose and multotriose, or mixtures of mono- and 
oligosaccharides can also be employed. 
The water content in the aqueous glycoses is from 10 to 80% by weight, 
preferably from 15 to 60% by weight. Industrial solutions, in particular 
dextrose syrup, which have a water content of from 20 to 40% by weight are 
preferred. 
The advantage in the use of aqueous glycoses lies not only in the easier 
availability of the glycose solutions, but also in the easier handling, 
particularly in the easier meterability into the preheated alcohol 
solution. 
The aliphatic primary alcohols employed can have virtually any desired 
chain lengths, i.e. those from about 8 to about 30 carbon atoms. In order 
to obtain effective surface-active reaction products which can be employed 
as surfactant raw materials in detergents and cleaners, aliphatic primary 
alcohols having from 8 to 20 carbon atoms, in particular those having from 
8 to 18 carbon atoms, are preferred. These higher aliphatic alcohols are 
preferably prepared from industrial fats. Of course, it is also possible, 
however, to employ synthetic primary alcohols such as oxo alcohols or 
Ziegler alcohols in the process of the invention. 
The aliphatic primary (C.sub.8 - to C.sub.18 -alcohols, in particular 
C.sub.12 - to C.sub.18 -alcohols, particularly important as the alcohol 
component are preferably saturated and in particular straight-chain 
alcohols, such as can be obtained by the hydrogenation of native fatty 
acids on the industrial scale. An important aspect in the process of the 
invention is the preparation of surfactants which can be prepared 
exclusively from renewable raw materials. Typical representatives of the 
higher aliphatic alcohols which can be used in the process of the 
invention are, for example, n-octyl alcohol, n-nonyl alcohol, n-decyl 
alcohol, n-undecyl alcohol, n-dodecyl alcohol, n-tridecyl alcohol, 
n-tetradecyl alcohol, n-hexadecyl alcohol or n-octadecyl alcohol. Since 
the fatty alcohols preferably originate from natural fat sources, 
customarily mixtures of industrial fatty alcohols are also suitable as 
reactants. 
In addition to the real fatty alcohols, branched-chain primary alcohols 
such as 2-ethylhexanol or such as oxo alcohols are also suitable for the 
reaction. Typical oxo alcohols are, for example, the compounds C.sub.12 
-C.sub.13 -alkanol having about 25% of principally 2-methyl branching 
(Dobanol 23) and the corresponding C.sub.9 -C.sub.11 -alkanol (Dobanol 
91). 
The batch ratios are selected in such a manner that the molar ratio of 
aliphatic alcohol to glycose is from 2:1 to 10:1, preferably from 3:1 to 
8:1, in particular from 3:1 to 6:1 (measure a). 
The acidic catalyst having emulsifying properties employed is the acidic 
form of anionic surfactants (measure b). Particularly suitable 
representatives of such surfactants which may be mentioned are: 
alkylbenzenesulfonic acids, in particular those of the formula 
##STR1## 
where R.sup.1 =C.sub.8 -C.sub.22 -alkyl (chain lengths of from C.sub.12 
to C.sub.14 are particularly preferred); 
alkylsulfonic acids, in particular those of the formula 
EQU R.sup.2 -SO.sub.3 H 
where R.sup.2 =C.sub.8 -C.sub.30 -alkyl; 
sulfosuccinic acid mono- or diesters, in particular those of the formula 
##STR2## 
where R.sup.3 =H or C.sub.6 -C.sub.22 -alkyl and R.sup.4 =C.sub.6 
-C.sub.22 -alkyl; 
sulfoalkylcarboxylic acids or -carboxylic acid esters, in particular those 
of the formula 
##STR3## 
where R.sup.5 =C.sub.4 -C.sub.22 -alkyl, R.sup.6 =C.sub.1 -C.sub.30 
-alkyl or H and m=0 to 10; 
mono- and dialkylnaphthalenesulfonic acids, in particular those of the 
formula 
##STR4## 
where R.sup.2 =C.sub.8 -C.sub.30 -alkyl and n=1 to 2. 
If an acidic catalyst which can simultaneously act as an emulsifier for the 
glycose in the alcohol is not employed in the process of the invention, 
the process cannot be carried out. Thus, severe aggregation occurs, for 
example, with p-toluenesulfonic acid and polyglycoses are formed in 
increased amounts. Alkylbenzenesulfonic acids and here, in particular, 
benzenesulfonic acids having C.sub.12 - to C.sub.14 -alkyl radicals in the 
p-position are particularly preferred. The catalyst concentration is from 
0.1 to 5% by weight, based on the amount of glycose employed. A catalyst 
concentration of from 0.5 to 2% by weight is preferred. 
It has been found that on addition of a further emulsifier to the reaction 
solution in addition to the emulsifying acidic catalyst a distinct 
improvement of the process is achieved. The further emulsifiers employed 
for this purpose are alkyl glycosides, in particular alkyl glucoside 
(measure c). 
Alkyl glycosides can be employed as solid substances or aqueous solutions. 
Advantageously, however, alcoholic solutions of alkyl glycosides are used. 
In a preferred embodiment, the process of the invention proposes that a 
fraction of the alkyl glycoside produced, which is present dissolved in 
the alcohol after conclusion of the glycosylation and neutralization, is 
retained and employed again in a following batch. As a result, the 
emulsifier does not have to be isolated. This procedure has the advantage 
that emulsification of the glycose is effected immediately at the start of 
the glycose addition due to the alkyl glycoside/alcohol mixture present in 
the reaction vessel. As a result, the glycose can be better reacted at the 
start of the addition phase and there is no turbidity or precipitation 
which can be attributed to increased formation of polyglycoses. If the 
emulsifier is omitted, considerable polyglycose formation occurs, i.e. the 
additional emulsifier is indispensable. 
All alkyl glycosides which can be prepared by the process of the invention 
can be employed as the additional emulsifier. The emulsifiers are thus not 
restricted to glucose derivatives. The emulsifiers employed can be either 
pure alkyl monoglycosides, or technical mixtures of alkyl monoglycosides, 
alkyl oligoglycosides and polyglycoses. This does not impair their 
effectiveness. 
Advantageously, as described above, an alcoholic solution of a technical 
alkyl glycoside mixture is used. As a basis of calculation for the amount 
of emulsifier employed in these alcoholic solutions, all sugar components 
(alkyl monoglycosides, alkyl oligoglycosides and polyglycoses) are summed 
and based on the glycose employed. Emulsifier concentrations of from 1 to 
30% by weight, preferably from 1 to 15% by weight, can be employed. 
Concentrations of from 1.0 to 8% by weight are particularly preferred. 
When carrying out the process of the invention, a procedure is used in 
which the aqueous glycose is preheated to 50.degree.-90.degree. C., better 
to 60.degree.-70.degree. C. (measure d). This leads to a distinct decrease 
in viscosity, so that the glycose can be added as an easily pourable 
liquid. In addition, a small temperature difference between added aqueous 
glycose solution and the reaction mixture is desirable in order to 
facilitate the supply of heat energy during the reaction. 
The addition of the aqueous glycose solution is carried out in portions or, 
better, continuously. The continuous addition is advantageously controlled 
in such a manner that the water introduced and the water resulting from 
the reaction is simultaneously removed by distillation under reduced 
pressure. In this process, the reaction is carried out in the 
heterogeneous phase with the formation of a stable glucose syrup/alcohol 
emulsion, particular caution during the addition for continuous formation 
of a homogeneous phase, as described in U.S. Pat. No. 4,996,306, not 
having to be maintained. Only good emulsification of the added glycose 
syrup has to be ensured. This can be achieved in a simple manner using the 
emulsifying additives already described (emulsifying acid, alkyl glycoside 
as emulsifier). A further effective measure for good emulsification is 
achieved by effective stirring of the reaction mixture, which is 
preferably effected on the laboratory scale by means of baffles and disk 
mixers. 
In pilot plant and full-scale batches, recycling apparatus through an 
external liquid circulation has proven particularly suitable and in 
addition has the advantage that the heat energy can be carefully added by 
means of a heat exchanger and high vessel wall temperatures can thus be 
avoided. Adverse effects of temperature control on the colour of the 
product can thus be prevented. 
Feeding-in or addition of the glucose syrup to the recycling line via a 
liquid jet pump has proven particularly advantageous. By appropriate 
choice of the recycling efficiencies (drive jet) and the dosage rate, 
optimum emulsification can be achieved so that virtually no precipitation 
of polyglycose in the reactor can be detected. 
Surprisingly, it has been possible to determine that, during the described 
heterogeneous direct procedure with the formation of an emulsion, the 
product quality with respect to, for example, monoglucoside content, 
polyglycose and color is better than with transacetalization methods known 
from the literature (cf. Example D). Even small particle-like 
precipitations of polymeric products (mainly polyglycose) do not impair 
the product quality. However, the particle-like precipitations must be 
below 2% by weight with respect to isolated product, since otherwise 
scorching and color damage of the product occur during distillation on the 
one hand, and on the other hand the yields of alkyl monoglucoside are 
lower (see Comparative Examples A, B and C). 
In principle, particle-like precipitations of polyglycose of this type can 
of course be removed by filtration of the crude product (cf. Comparative 
Example A), which means, however, an additional process step. In the above 
process, however, this is not necessary in the case of small 
precipitations (&lt;2% by weight with respect to isolated product). 
Since in the present process the product quality is neither impaired by 
working in heterogeneous phase with the formation of a stable emulsion nor 
by the formation of small precipitations, the process represents a 
simplified, economical route for the synthesis of alkyl polyglycosides and 
thus an improvement of the prior art. 
The reaction mixture of alcohol, acidic catalyst and alkyl glycosides is 
preheated to 100.degree.-150.degree. C., better 110.degree.-120.degree. 
C., before the start of glycose addition and the reaction is carried out 
in this temperature range (measure e). The water addded with the glycose 
addition and the water formed during the acetal formation is continuously 
removed from the emulsion by distillation under reduced pressure (measure 
e). Depending on the higher alcohol employed, the pressure is selected to 
be from 10 to 100 mbar. The higher the boiling point of the alcohol or 
alcohol mixture employed, the lower can be the reduced pressure selected. 
For instance, with a straight-chain C.sub.8 /C.sub.10 alcohol mixture a 
reduced pressure of expediently from 50 to 60 mbar is selected, while with 
a C.sub.12 /C.sub.14 alcohol mixture a reduced pressure of from 30 to 40 
mbar is preferred. 
After conclusion of the glycose addition, the mixture is expediently 
stirred for a further 10 min-2 h in the temperature range indicated. The 
content of free glycose in the reaction solution has then normally fallen 
to below 0.5% by weight, i.e. the glycose has virtually completely 
reacted. 
Suitable neutralizers for deactivating the acidic catalyst after the 
reaction (measure f) are in particular basic alkali metal, alkaline earth 
metal or aluminum salts, the anions of which can be of organic or 
inorganic nature. Examples of bases of this type are sodium hydroxide, 
potassium hydroxide, calcium hydroxide, aluminum hydroxide, sodium 
acetate, sodium methoxide and sodium ethoxide. The use of aqueous sodium 
hydroxide solution is preferred, since this can be easily incorporated 
into the alcohol/product mixture, can be easily added and does not require 
a filtration step for salts which may precipitate. The neutralization is 
carried out so that a slightly basic solution of pH 8-10, measured as a 
1:1 mixture of water:fatty alcohol/product, is then present. For 
neutralization, the hot reaction solution is expediently cooled somewhat 
beforehand, for example to 70.degree.-100.degree. C. 
The distillation of the excess alcohol (measure g) is carried out by known 
techniques which are gentle to the process product, for example by means 
of a thin layer evaporator, and at from 0.01 to 10 mbar, the pressure 
being dependent on the boiling point of the alcohol or alcohol mixture 
employed. For this purpose, a prior filtration of, for example, 
precipitated polyglycose is not as a rule necessary. 
The almost alcohol-free product obtained is processed by addition of water 
to give a 30-70% strength by weight, preferably about 50% strength by 
weight, aqueous paste and bleached with a compound which eliminates active 
oxygen such as, for example, 30% strength by weight aqueous hydrogen 
peroxide solution (measure h). The bleaching is customarily carried out at 
from 70.degree. to 90.degree. C., the pH during the bleaching process 
being checked and optionally adjusted to values of from pH 8 to pH 10 
using, for example:, sodium hydroxide. The amount of hydrogen peroxide 
used is as a rule 0.3-3% by weight, calculated as H.sub.2 O.sub.2 and 
based on the amount of the product after removal of the alcohol. 
The present invention is a combination of the individual measures (a) to 
(h), the individual measures partly already being known as such from the 
prior art. The carrying-out of the glycosylation in two phases, which are 
present as anemulsion and contain virtually no polyglycose or less than 2% 
by weight of polyglycose, is new. The advantage of the process of the 
invention lies in the combination of several individual advantages 
originating from the individual measures (a) to (h), whose interaction 
leads to an outstanding and surprising overall result. 
Using the process of the invention, an outstanding product quality is in 
particular obtained, and the alkyl glycosides prepared are only faintly 
colored and contain only a small amount of alkyl oligo- and 
polyglycosides. 
Easily available and readily handleable aqueous glycoside solutions can 
advantageously be used as starting materials and resort no longer has to 
be made to solid glycosides which are dehydrated by troublesome processes 
and optionally processed to specific particle sizes. 
The process of the invention is easy and problem-free to carry out, there 
are, for example, no addition problems or difficulties during the supply 
or removal of heat, also troublesome filtration processes are normally not 
necessary. The process is simple, and it is achieved with a minimum of 
chemical reactants and a minimum of process measures. The process works at 
high efficiency with respect to the space-time yield, and the products 
obtained are sufficiently pure. The process is thus to a great extent 
economical. 
The process of the invention finally permits problem-free transfer to the 
large industrial scale without scaling-up problems.

EXAMPLES 
Parts and percentages are by weight. 
Example 1 
825 g of dodecanol (4.57 mol) were initially introduced into a 2-1 
multi-necked stirrer reactor with a baffle,-disk mixer, thermometer, 
distillation head and a metering unit, consisting of a metering pump, 
pressure-retaining valve and a nozzle, and 2.6 g (0.008 mol) of 
dodecylbenzenesulfonic acid were added thereto. This mixture was treated 
with 121.6 g of an alkyl glucoside/dodecanol emulsifier mixture 
(composition: 63% dodecanol (0.41 mol), 22.6% C.sub.12 -monoglucoside, 
5.2% C.sub.12 -diglucoside, 2.2% C.sub.12 -triglucoside, 0.7% C.sub.12 
-tetraglucoside, &lt;0.5% C.sub.12 -pentaglucoside and 5.9% polyglucose). In 
this case, the glucose-containing proportions of the emulsifier were 30% 
with respect to the gluocose employed. The molar ratio of fatty alcohol to 
glucose was 6:1. 
The solution was heated to 115.degree.-120.degree. C. 214 g (0.83 mol) of a 
dextrose syrup heated to 60.degree. C. (70% strength solution, glucose 
content about 99.5%) were continuously metered in under reduced pressure 
at from 30 to 35 mbar so that a cloudy emulsion was formed which contains 
virtually no particle-like precipitations of polyglucose. At the same 
time, both the water added with the syrup and the water produced in the 
reaction was removed to equilibrium by distillation at the given reduced 
pressure. It was important in this connection that an optimum distribution 
of the dextrose syrup in the fatty alcohol was ensured by the combination 
of disk mixer (200 rpm), baffle and metering by means of a nozzle. After a 
metering time of 4 h and a stirring time of 30 min, 83 g of water were 
removed by distillation. A slightly turbid, pale-yellow reaction solution 
was obtained. 
After cooling to 90.degree. C., the catalyst was deactivated using 1.6 g of 
50% strength sodium hydroxide solution; the resulting solution had a pH of 
8.3 (measured in 50% strength aqueous solution). The excess alcohol was 
removed by means of a thin layer evaporator (heating temperature 
170.degree. C., outlet temperature 140.degree. C.) under a reduced 
pressure of 1 mbar. The amount of distillate was 820 g. The product (240 
g) was processed directly in paste form by addition of water to give a 50% 
strength aqueous solution and bleached at 80.degree. C. using 12.3 g of 
H.sub.2 O.sub.2 (30% strength solution). The iodine color number was 15. 
The composition of the product is shown in the Table given below. 
Comparative Example A 
(p-toluenesulfonic acid as catalyst) 
The dodecylbenzenesulfonic acid in Example 1 was replaced by 1.5 g (0.008 
mol) of p-toluenesulfonic acid. After the metering of the dextrose syrup, 
a highly turbid crude product permeated with solid particles was obtained 
with a procedure similar to Example 1. Filtration gave 25 g of residue 
which consisted to about 80% of polyglucose. The filtrate (210 g) worked 
up in a manner similar to Example 1 had the composition shown in the Table 
given below. 
Comparative Example B 
(poor dispersion) 
Example 1 was repeated, only in contrast to Example 1 a dropping funnel was 
employed instead of the nozzle to meter the dextrose syrup. After metering 
of the syrup, a turbid solution was obtained which contained considerable 
agglutinations. Filtration gave 64 g of residue (about 80% polyglucose). 
Dispensing with the baffle and disk mixer led to a still poorer dispersion 
of the dextrose syrup. Over 50% of the glucose was isolated as polyglucose 
after filtration. 
Examples 2 to 5 
The procedure was as in Example 1 with variation of the alkyl glucoside 
concentration. The results are summarized in the Table given below. 
Comparative Example C 
(without alkyl glucoside as emulsifier) 
Example 1 was repeated., only in contrast to Example 1 no alkyl glucoside 
was added as additional emulsifier. After metering of the dextrose syrup, 
a turbid solution permeated with solid particles was present. 47 g of 
residue which consisted to over 80% of polyglucose were removed by 
filtration. The filtrate (195 g) worked up in a manner similar to Example 
1 had the composition shown in the Table given below. 
Example 6 
Corresponding to Example 4, 606 g of dodecanol (3.25 mol), 16.7 g of the 
same alkyl glucoside/dodecanol emulsifier mixture as in Example 1 (3% 
based on glucose employed) and 2.6 g (0.008 mol) of dodecylbenzenesulfonic 
acid were reacted with 214 g (0.83 mol) of the same dextrose syrup as in 
Example 1 with the formation of an emulsion. The molar ratio of fatty 
alcohol to glucose was 4:1. After removal of water, a slightly turbid 
solution was obtained. Distillation gave 500 g of distillate and 245 g of 
product which after bleaching with 30% strength H.sub.2 O.sub.2 solution 
(12.3 g) had an iodine color number of 13 (as a 50% aqueous paste). The 
composition of the product is shown in the Table given below. 
Examples 7 and 8 
The procedure was as in Example 6 with further variation of the molar ratio 
of fatty alcohol to glucose. The results are summarized in the Table given 
below. They show that the alkyl monoglucoside content falls and the 
polyglucose content rises with decreasing molar ratios. An acceptable 
ratio between product composition and making full use of the flask or 
vessel volume is achieved at molar ratios of 3:1 to 4:1. 
TABLE 
__________________________________________________________________________ 
Conditions and results of Experiments 1 to 8 and Comparative Examples A 
to C 
Iodine 
Alkyl color number 
glucoside of the 
conc. Composition of the product product (50% 
(% based Poly- 
strength 
on C.sub.12 OH: 
C.sub.12 OH 
C.sub.12 --Glu 
C.sub.12 --Fru 
C.sub.12 --Glu.sub.2 
C.sub.12 --Glu.sub.3 
C.sub.12 --Glu.sub.4 
glucose 
aqueous 
Ex. glucose) 
glucose 
Yield 
% % % % % % % solution) 
__________________________________________________________________________ 
1 30 6:1 240 g 
1.5 52.0 2.0 14.0 6.0 2.0 about 
15 
A* 30 6:1 210 g 
1.8 42.0 1.5 10.5 6.5 2.5 about 
34 
B** 30 6:1 -- -- -- -- -- -- -- mainly 
-- 
2 15 6:1 235 g 
2.0 54.0 1.5 14.5 6.3 2.0 about 
21 
3 7.5 6:1 242 g 
2.0 58.5 2.1 13.2 5.9 1.8 about 
14 
4 3 6:1 252 g 
1.4 64.5 2.2 12.9 5.9 2.0 about 
11 
5 1.5 6:1 237 g 
1.8 60.8 1.8 13.2 5.8 1.5 about 
21 
C*** 
0 6:1 195 g 
1.7 56.7 1.7 12.8 4.2 1.3 about 
45 
6 3 4:1 245 g 
1.7 55.5 1.2 14.8 7.1 2.4 about 
13 
7 3 3:1 225 g 
2.0 48.1 1.0 16.0 7.4 3.0 about 
17 
8 3 2:1 205 g 
1.1 41.3 0.8 19.2 6.9 2.5 about 
22 
D**** 
0 238 g 
1.5 53.0 1.8 11.0 5.1 1.5 about 
20 
__________________________________________________________________________ 
Explanatory notes to the Table: 
*additional residue of 25 g (about 80% polyglucose) 
**polyglucose as predominant product 
***additional residue of 47 g (&gt;80% polyglucose) 
****6.0% butyl glucoside containing 
C.sub.12 OH = dodecanol, C.sub.12 --Glu.sub.2 = dodecyl monoglucoside, 
C.sub.12 Fru = dodecyl monofructoside, C.sub.12 Glu.sub.2 = dodecyl 
diglucoside, C.sub.12 Glu.sub.3 = dodecyl triglucoside, 
C.sub.12 Glu.sub.4 = dodecyl tetraglucoside 
Example 9 
Corresponding to Example 6, 630 g of Lorol 1214 special (fatty alcohol 
mixture, from Henkel containing about 75% dodecanol, about 23% 
tetradecanol and about 1% hexadecanol; OH number=295 mg of KOH/g) were 
employed as the alcohol component. The emulsifier concentration was 3%, 
based on glucose employed. The composition of the emulsifier was 64% 
C.sub.12 /C.sub.14 alcohol, 23% alkyl monoglucoside, about 5% alkyl 
diglucoside, about 2% alkyl triglucoside, &lt;0.5% alkyl tetra- and alkyl 
pentaglucoside, and about 5% polyglucoside (alkyl: C.sub.12 /C.sub.14 
/C.sub.16 mixture). After addition of dextrose syrup, the reaction mixture 
is present as an emulsion. Removal of water from this gives a slightly 
turbid solution. After distillative working-up and bleaching with 30% 
strength H.sub.2 O.sub.2 solution (14.7 g), 510 g of product were obtained 
as a 50% strength aqueous solution having an iodine color number of 9. The 
composition of the product was 1.9% C.sub.12 /C.sub.14 alcohol; 57% 
dodecyl/tetradecyl monoglucoside, 1.9% dodecyl/tetradecyl fructoside, 
14.4% dodecyl/tetradecyl diglucoside, 7.7% dodecyl/tetradecyl 
triglucoside, &lt;3% dodecyl/tetradecyl tetra- and pentaglucoside, about 15% 
polyglucose and &lt;0.5% free glucose. The hexadecyl contents were not 
analyzed. 
Other native alcohol mixtures such as C.sub.8 /C.sub.10 or C.sub.10 
/C.sub.12 alcohol mixtures (for example Lorol C 8-10 or Lorol C 10-12 from 
Henkel) gave an analogous spectrum in the product composition. 
Comparative Example D 
In a manner similar to the prior art disclosed in EP-A-0,301,298, an alkyl 
polyglucoside based on dodecanol was prepared by the transacetalization 
method via the butyl glucoside intermediate. The molar ratios butanol: 
glucose:dodecanol were 6:1:6. The composition of the product can be taken 
from the Table and shows clearly that a qualitatively better product can 
be prepared using the described direct procedure. 
Example 10 
A 335 1 enamel vessel with an impeller stirrer and an external recycling 
apparatus consisting of a recycling-line and conveyor pump was used. A 
liquid jet pump (Wiegand) for metering the glucose syrup was incorporated 
into the recycling line. 
The following amounts of substance were employed: 
150 kg of Lorol 1214 special (cf. Example 9) 
4.2 kg of emulsifier mixture (composition similar to Example 9) 
0.6 kg of dodecylbenzenesulfonic acid 
51.5 kg of glucose syrup (70% strength aqueous solution) 
Lorol 1214 special, emulsifier mixture and catalyst were initially 
introduced into the reactor, heated to 115.degree. to 120.degree. C. and 
mixed at a recycling capacity of 600 l/h. Glucose syrup preheated to 
60.degree. C. was metered in over the course of 4 h by means of the liquid 
jet pump and solvent water and water of reaction were simultaneously 
removed by distillation at from 40 to 50 mbar. The amount of water removed 
was 20.2 kg. The mixture was stirred for 30 min after metering of the 
syrup had ended, almost no particle precipitations of polyglucose being 
found (&lt;1% based on final product). The mixture was subsequently 
neutralized with 200 g of 50% strength aqueous sodium hydroxide solution. 
After distillative working-up and bleaching of the product using 30% 
strength H.sub.2 O.sub.2 solution (0.8 kg), 115 kg of product were 
obtained as a 50% strength aqueous solution (iodine color number 7). The 
composition of the product was 1.6% residual alcohol, 56.5% 
dodecyl/tetradecyl monoglucoside, 2.1% dodecyl/tetradecyl fructoside, 
13.3% dodecyl/tetradecyl diglucoside, 7.5% dodecyl/tetradecyl 
triglucoside, &lt;3% dodecyl/tetradecyl tetra- and pentaglucoside, about 16% 
polyglucose and &lt;0.5% free glucose. The hexadecyl contents were not 
analyzed.