The present invention relates to a new alkyl gluco¬ side presenting an advantageous combination of good clean- ing power and low foaming, which renders it particularly suitable for cleaning hard surfaces.

In recent years, attention has focused on alkyl glu¬ cosides, since these have proved to be more easily bio¬ degradable than other non-ionic surfactants, such as ethy- lene oxide adducts of fatty alcohols. US Patent Specifica¬ tion 3,839,318 thus describes the production of alkyl glu¬ cosides and alkyl oligosaccharides, such as n-octyl gluco¬ side, n-hexyl glucoside, n-decyl glucoside, n-dodecyl glu¬ coside, isodecyl glucoside, isoundecyl glucoside, isotri- decyl glucoside and the corresponding oligosaccharides. The United States Stationary Invention Registration H171 states that alkyl glucosides of formulae R(OG) and R(0G) are excellent surfactants. In these formulae, R is an alkyl or alkenyl group which is branched at the second carbon atom or at a higher carbon atom, the branch being selected from the group methyl, ethyl, isopropyl, n-pro- pyl, butyl, pentyl, hexyl and mixtures thereof, provided that R contains from about 7 to about 30 carbon atoms; G is a saccharide group selected from the group glucose, fructose, mannose, galactose, talose, allose, altrose, idose, arabinose, xylose, lyxose, ribose and mixtures thereof; and x is 2 or more. Example 1 contains a descrip¬ tion of the production of two product mixtures substan¬ tially made up of 2-ethylhexyl glucoside and isooσtyl glu- coside, respectively.

DE 20 36472, EP 306 650, EP 306 651 and EP 366 652, inter alia, also describe alkyl glucosides.

Even though alkyl glucosides generally are easily biodegradable, they are only used to a limited extent in many ranges of application, such as the cleaning of hard surfaces, since they are too high-foaming and/ or have a poor cleaning power. Also, alkyl glucoside products con-

taining branched alkyl groups often have a disagreeable smell. It is therefore a desideratum to provide non-ionic surfactants which are about as easily biodegradable, but which have a better cleaning power and/or are more low- foaming than known alkyl glucosides.

According ^" to the invention, it has now surprisingly been found that an alkyl glucoside of the general formula

wherein R is an alkyl group having 2-5 carbon atoms,

2 preferably 2-4 carbon atoms; R is an alkyl group having

4-7 carbon atoms, preferably 5 or 6 carbon atoms, the sum of the carbon atoms in R1 and R2 being 7-11, preferably

7-9, G is a monosaccharide residue, and x is 1-4, prefer¬ ably 1 or 2, has good cleaning and wetting properties and is low-foaming compared with other alkyl glucosides of approximately the same chain length. Compounds of formula

(I) in which R1 is an alkyl group having 3 carbon atoms,

2 R is an alkyl group having 5 carbon atoms, and G is a glucose residue, are especially preferred. The glucosides according to the invention do not have any disagreeable smell. In addition, they have been found to be easily degradable and have low biotoxicity. Tests have not shown any skin irritations caused by the alkyl glucosides.

The inventive compounds can be produced in conven¬ tional manner by reacting an alcohol of formula

1 2 wherein R and R are as indicated above, with a monosac- charide, the molar ratio of the alcohol to the monosaccha¬ ride being 2:1-80:1, in the presence of an acid catalyst.

The catalyst may be an inorganic or organic acid. The reaction is carried out under vacuum at 90-120°C for about 1-4 h. Conveniently, the resulting reaction mixture is first filtered and then neutralised with an organic and/or an inorganic base. Finally, excess alcohol is carefully removed, e.g. by distillation, if so desired.

The alcohols of formula (II) can be obtained by a Guerbet reaction starting from n-pentanol, n-hexanol or mixtures of n-pentanol and n-hexanol, n-pentanol and n- -butanol, n-hexanol and n-butanol, and n-hexanol and n- -pentanol, or by an aldol condensation of the correspond¬ ing aldehydes. Preferably, the alkanol of formula (II) is 2-propyl heptanol. The monosaccharide used as reactant suitably is pentose and hexose. Specific examples of mono- saccharides used in the production of the inventive gluco¬ sides are glucose, mannose, galactose, talose, allose, altrose, idose, arabinose, xylose, ribose and lyxose. Glu¬ cose is usually preferred for commercial reasons.

The inventive alkyl glucosides are suitably used as surfactants in cleaning compositions, e.g. for degreas- ing hard surfaces or washing up. Excellent results are obtained in the degreasing of lacquered or unlacquered metal surfaces. Apart from the inventive alkyl glucoside, these compositions preferably contain a water-soluble solubiliser and suitably contain a complexing agent.

Examples of solubilisers are alkyl ether polyalky- lene glycol, such as monobutyl diethylene glycol; glycols, such as diethylene glycol, dipropylene glycol and propy- lene glycol; alcohols, such as ethanol, propanol and iso- propanol; alkyl glucosides in which the alkyl group has 4-18 carbon atoms; and/or tertiary or quaternary amine alkoxylates, in which the alkyl group, which may be straight or branched, saturated or unsaturated, has 8-20 carbon atoms, and 6-30 mol of alkylene oxide is added per mol of amine. Preferably, 50-100 mol per cent of the added alkylene oxide consists of ethylene oxide, while the remaining amount preferably consists of propylene oxide or

a mixture of propylene oxide and butylene oxide. The dif¬ ferent alkylene oxides can be added randomly or in blocks. If the cleaning composition should be low-foaming, the alkylene oxide chain suitably ends with an addition of 1-5 mol of propylene oxide and/or butylene oxide. Usually, the ratio of solubiliser to the inventive alkyl glucoside is 1:10-5:1, preferably 1:3-3:1.

The complexing agent may be a conventional inorganic or organic complexing agent, such as an inorganic phos- phate or NTA, EDTA, citric acid or a polycarboxylate. The amount added may vary from nothing at all to 300% by weight of the inventive alkyl glucoside. Preferably, the quantity ratio of the complexing agent to the alkyl gluco¬ side is 1:10-2:1. The cleaning compositions may further contain other additives, such as pH-adjusting agents, antifoaming agents, enzymes, other surfactants and scents. The compo¬ sitions are usually aqueous and in the form of emulsions, microemulsions or solutions. The invention will be further illustrated by the fol¬ lowing Examples. Example 1

An alkyl glucoside was produced by reacting 3 mol of 2-propylheptanol with 0.45 mol of glucose in the presence of 0.015 mol of sulphuric acid as catalyst at 110°C and 70 mbar. The reaction was interrupted after 65 min. The resulting product mixture was treated by distilling off excess alcohol under vacuum. The yield was 50 g, consist¬ ing of 74% of 2-propylheptyl monoglucoside, 15% of 2-pro- pylheptyl diglucoside and a residue of higher oligomers. The glucosides had an average degree of polymerisation (DP) of about 1.3. The structure was determined by gas chromatography, mass spectrometry and NMR. Example 2 As in Example 1, 2-butyloctanol was reacted with glu¬ cose. The reaction temperature was 112°C, and the reaction time was 90 min. The average DP was 1.5.

Example 3

Here, 20 ml of each of the cleaning compositions below, diluted with 10 parts by weight of water per part by weight of the composition, was applied to a vertically arranged iron sheet soiled with mineral oils, soot, salts and clay. After application, the coated surface was rinsed with water without any mechanical treatment.

Components Composition, % by weight

1 2 3 4 A B C D E

Glucoside (Example 1) 5 5 5

Glucoside (Example 2) 5

Glucoside A 8.5 5

Glucoside B 5

Glucoside C 5

Glucoside D 5

Butyldiethylene glycol 11 11 11 11 11 11 11

Quaternary ethoxy- lated fatty amine

(Berol 555) 4

NTA 5 5 3 3 3 3 3 3 5

Water 86 79 83.5 81 81 81 81 81 84

Glucoside A = 2-ethylhexyl-0(G) H

Glucoside B = isooctyl-O(G) H

Glucoside C = n-dodecyl/n-tetradecyl glucoside (Plantaren,

APG-600, Henkel) Glucoside D = n-decyl glucoside (Lutensol GD-70, BASF) G = glucoside residue and x = 1.5 (average value).

The resulting cleaning effect was assessed with respect to the area of the cleaned surface, as well as the actual cleanness of this surface, the figure 1 indi¬ cating no improvement and the figure 10 indicating a per¬ fectly clean surface. The following results were obtained.

2

Composition Cleaned surface, cm Cleanness

1 88 8

2 120 8

3 128 8

4 112 8

A 0 1

B 80 4

C 48 6

D 72 6

E 0 1

The foaming of the different ready-to-use solutions was measured according to Ross-Miles ASTM D 1173-53. The following results were obtained.

Foam height, mm

Composition

Instantaneously After 5 min

1 19 3

2 23 5

3 8 5

4 30 7

A 7 0

B 20 3

C 67 63

These results show that the alkyl glucosides accord¬ ing to the invention have an excellent cleaning power and are clearly superior to alkyl glucosides having a straight carbon chain with 10-14 carbon atoms, while at the same time showing an acceptable degree of foaming. The compo¬ sition containing alkyl glucosides having an alkyl group with 8 carbon atoms shows an unsatisfactory cleaning power.