Microcapsules containing a gas-releasing photolabile compound and uses thereof

Abstract

The present invention relates to water-dispersible microcapsules that include an oil phase, e.g. a perfume, containing a photolabile compound capable of generating a gas upon exposure to light. The gas is able to cause an extension or the breaking of the microcapsule allowing the release of the oil phase and thus increasing the long-lastingness of the odor perception. The present invention concerns also the use of such microcapsules in perfumery as well as the perfuming compositions or perfumed articles that include such microcapsules therein to provide a prolonged release of fragrant molecules.

Claims

1. A non-diffusive core-shell microcapsule comprising: a) a core comprising: an oil phase; at least one photolabile compound capable of generating, upon exposure to light at a wavelength comprised between 900 and 300 nm, a gas selected among the group consisting of C.sub.2-C.sub.4 alkenes; wherein the at least one photolabile compound comprises an alkyl aromatic ketone of formula: ##STR00006## wherein each R.sup.1 represents, independently of each other, a hydrogen atom, a fluorine or chlorine atom, a hydroxyl or amino group or a C.sub.1-2 alkyl, C.sub.1-2 alkoxy, C.sub.1-2 dialkylamino or COR.sup.2 group wherein R.sup.2 represents a hydrogen atom or a C.sub.1-4 alkyl group, provided that at least two R.sup.1 represent a hydrogen atom; or two adjacent R.sup.1, when taken together, represent a OCH.sub.2O group, a OCH.sub.2CH.sub.2O group or a C.sub.3-4 alkanediyl group, optionally substituted with one to four methyl groups; and wherein R.sup.2 represents a propyl, n-butyl, or sec-butyl group; and optionally comprising at least one photo-catalyst; and b) a shell surrounding said core having a wall thickness of between 10 and 350 nm and being formed by interfacial polymerization or by a phase separation process induced by polymerization or by coacervation, wherein exposure of the microcapsule to light having a wavelength of between 900 and 300 nm generates a gas in the core that causes breakage of the shell to allow a greater release of the oil phase than microcapsules that do not contain the at least one photolabile compound.

2. The microcapsule according to claim 1, which comprises, based on the total microcapsule weight, from about 10% to about 50% of photolabile compounds.

3. The microcapsule according to claim 1, which comprises, based on the total microcapsule weight, from about 20% to about 96% of oil phase.

4. The microcapsule according to claim 1, wherein the photo-catalyst is present and comprises from 1% to 20% based on the total microcapsule weight.

5. The microcapsule according to claim 1, wherein the shell surrounding the core is an aminoplast, polyamide, polyester, polyuria or polyurethane resins or a mixture thereof.

6. The microcapsule according to claim 1, wherein the shell has a thickness varying between 25 and 350 nm.

7. The microcapsule according to claim 1, wherein the oil phase comprises a perfuming oil.

8. The microcapsule according to claim 1, wherein the photolabile compound is butyrophenone, 4-methoxybutyrophenone, 4-hydroxybutyrophenone, 3,4-(methylenedioxy)butyrophenone, valerophenone, 2-hydroxyvalerophenone, 4-hydroxyvalerophenone or isovalerophenone.

9. The microcapsule according to claim 1, wherein the photolabile compound is butyrophenone.

10. A consumer product comprising: i) as a perfuming ingredient, at least one microcapsule as defined in claim 7; and ii) optionally, a free perfume oil.

11. The consumer product according to claim 10, in the form of a perfume, a fabric care product, a body-care product, an air care product or a home care product.

12. The consumer product according to claim 10, in the form of a fine perfume, a cologne, an after-shave lotion, a liquid or solid detergent, a fabric softener, a fabric refresher, an ironing water, a paper, a bleach, a shampoo, a coloring preparation, a hair spray, a vanishing cream, a deodorant or antiperspirant, a perfumed soap, shower or bath mousse, oil or gel, a hygiene product, an air freshener, a ready to use powdered air freshener, a wipe, a dish detergent or hard-surface detergent.

13. A consumer product comprising: i) as a perfuming ingredient, at least one microcapsule as defined in claim 9; and ii) optionally, a free perfume oil.

14. The consumer product according to claim 13, in the form of a perfume, a fabric care product, a body-care product, an air care product or a home care product.

15. The consumer product according to claim 13, in the form of a fine perfume, a cologne, an after-shave lotion, a liquid or solid detergent, a fabric softener, a fabric refresher, an ironing water, a paper, a bleach, a shampoo, a coloring preparation, a hair spray, a vanishing cream, a deodorant or antiperspirant, a perfumed soap, shower or bath mousse, oil or gel, a hygiene product, an air freshener, a ready to use powdered air freshener, a wipe, a dish detergent or hard-surface detergent.

16. The non-diffusive core-shell microcapsule according to claim 1, wherein: the core consists of a perfuming oil, the at least one photolabile compound and, optionally, the photocatalyst.

17. The microcapsule according to claim 7, wherein the photolabile compound is butyrophenone.

18. The microcapsule according to claim 17, wherein the oil phase comprises a perfuming oil.

19. The microcapsule according to claim 18, wherein the photolabile compound is butyrophenone.

20. A method of releasing a perfuming oil from a non-diffusive core-shell microcapsule, which comprises: providing the perfume oil in a microcapsule that has a core and shell surrounding the core, wherein the core comprises: at least one photolabile compound capable of generating, upon exposure to light at a wavelength comprised between 900 and 300 nm, a gas selected among the group consisting of C.sub.2-C.sub.4 alkenes, wherein the at least one photolabile compound comprises an alkyl aromatic ketone of formula: ##STR00007## wherein each R.sup.1 represents, independently of each other, a hydrogen atom, a fluorine or chlorine atom, a hydroxyl or amino group or a C.sub.1-2 alkyl, C.sub.1-2 alkoxy, C.sub.1-2 dialkylamino or COR.sup.2 group wherein R.sup.2 represents a hydrogen atom or a C.sub.1-4 alkyl group, provided that at least two R.sup.1 represent a hydrogen atom; or two adjacent R, when taken together, represent a OCH.sub.2O group, a OCH.sub.2CH.sub.2O group or a C.sub.3-4 alkanediyl group, optionally substituted with one to four methyl groups; and wherein R.sup.2 represents a propyl, n-butyl, or sec-butyl group; and optionally, at least one photo-catalyst; forming the shell about the core with a wall thickness of between 10 and 350 nm by interfacial polymerization or by a phase separation process induced by polymerization or by coacervation, and exposing the microcapsule to light having a wavelength of between 900 and 300 nm to generate a gas in the core in an amount sufficient to cause breakage of the shell to allow a greater release of the perfume oil than microcapsules that do not contain the at least one photolabile compound.

21. The method of claim 20 wherein the photolabile compound is butyrophenone.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1: Comparison of the amount of Romascone released from microcapsules containing 1-phenylbutan-1-one (butyrophenone; origin: Aldrich) capable of generating a gas according to the invention prepared in Example 3 () and from equivalent prior-art microcapsules without butyrophenone prepared in Comparative Example 3 ( ) as determined by dynamic headspace analysis after exposure of the microcapsules to light. The position of the arrow indicates the beginning of UV light irradiation.

EXAMPLES

(2) The invention is hereafter described in more detailed manner by way of the following examples, wherein the abbreviations have the usual meaning in the art, temperatures are indicated in degrees centigrade ( C.). NMR spectral data were recorded in CDCl.sub.3 (if not stated otherwise) on a Bruker AMX 400 or 500 spectrometer at 400 or 500 MHz for .sup.1H and at 100.6 or 125.8 MHz for .sup.13C, the chemical displacements are indicated in ppm with respect to Si(CH.sub.3).sub.4 as the standard, the coupling constants J are expressed in Hz (br.=broad peak). Commercially available reagents and solvents were used without further purification if not stated otherwise. Reactions were carried out in standard glassware under N.sub.2.

(3) Although specific conformations or configurations are indicated for some of the compounds, this is not meant to limit the use of these compounds to the isomers described. According to the invention, all possible conformation or configuration isomers are expected to have a similar effect.

Example 1

Preparation of Photolabile Compounds Capable of Generating a Gas Upon Exposure to Light

Preparation of 2-(9-oxo-9H-xanthen-2-yl)acetic acid

(4) A mixture of 2-iodobenzoic acid (5.00 g, 20.16 mmol, origin: Aldrich), 2-(4-hydroxyphenyl)acetic acid (4.30 g, 28.2 mmol, origin: Acros), Cs.sub.2CO.sub.3 (25 g, 77.0 mmol) in dioxane (100 mL) was stirred at room temperature. After 10 min, tris(2-(2-methoxyethoxy)ethyl)amine (0.78 g, 2.42 mmol) and CuCl (0.24 g, 2.41 mmol) were added. The mixture was heated under reflux (100 C.) for 20 h. After cooling to room temperature, the solvent was removed under reduced pressure and the remaining solid dissolved in aqueous NaOH (0.1 M, 100 mL) and filtered. The green filtrate was transferred to a separatory funnel, acidified with aqueous HCl (1 M, 33 mL) and extracted with ethyl acetate (330 mL). The combined organic layers were dried (Na.sub.2SO.sub.4) and concentrated under reduced pressure to give 7.86 g of a brown solid. Concentrated sulfuric acid (12 mL) was carefully added and the mixture heated at 85 C. for 1 h. After cooling to room temperature, the mixture was poured onto ice (70 g). The aqueous solution was transferred to a separatory funnel with water and extracted with ethyl acetate (330 mL). The combined organic phases were dried (Na.sub.2SO.sub.4) and the solvent removed under reduced pressure. The residue was dissolved in a mixture of toluene (15 mL) and methanol (3 mL) and heated at reflux (ca. 70 C.). After cooling to room temperature, the product crystallized. The product was taken up in toluene (15 mL), re-heated to reflux to dissolve and left re-crystallizing overnight to give 0.20 g (4%) of fine white crystals.

(5) .sup.1H-NMR (500 MHz, DMSO-D.sub.6): 12.56 (br. s, 1H), 8.20 (dd, J=8.0, 1.6, 1H), 8.09 (d, J=2.3, 1H), 7.90-7.84 (m, 1H), 7.78 (dd, J=8.7, 2.3, 1H), 7.68-7.63 (m, 1H), 7.62 (d, J=8.7, 1H), 7.51-7.45 (m, 1H), 3.79 (s, 2H).

(6) .sup.13C-NMR (125.8 MHz, DMSO-D.sub.6): 175.83 (s), 172.43 (s), 155.49 (s), 154.40 (s), 136.89 (d), 135.39 (d), 131.33 (s), 126.24 (d), 125.91 (d), 124.22 (d), 120.98 (s), 120.68 (s), 118.09 (d), 117.97 (d), 39.56 (t).

Preparation of ethyl(2-oxo-2-(pyren-1-yl)ethyl)carbonate

(7) Cesium formate (8.26 g, 46.4 mmol) was dissolved in pure methanol (50 mL) at 45 C. After cooling to room temperature, 2-bromo-1-(pyren-1-yl)ethanone (5.00 g, 15.5 mmol, origin: Aldrich) was added and the mixture was heated under reflux for 4 h. The solvent was removed under reduced pressure, the residue taken up in ethyl acetate (50 mL) at 45 C. and filtered through a sintered glass frit. The filtrate was concentrated and dried under high vacuum at room temperature for 2 h to give 2.24 g of 2-hydroxy-1-(pyren-1-yl)ethanone as an orange solid.

(8) .sup.1H-NMR (500 MHz): 9.14 (d, J=9.3, 1H), 8.17 (d, J=7.7, 1H), 8.16 (d, J=7.7, 1H), 8.13 (d, J=9.3, 1H), 8.10 (d, J=8.0, 1H), 8.06 (d, J=9.0, 1H), 7.99 (t, J=7.7, 1 H), 7.95 (d, J=8.0, 1H), 7.90 (d, J=9.0, 1H), 5.00 (s, 2H), 3.70 (br. s, 1H).

(9) .sup.13C-NMR (125.8 MHz): 200.95 (s), 134.82 (s), 130.80 (s), 130.46 (d), 130.22 (d, 2s), 126.84 (d), 126.76 (d), 126.49 (d), 126.47 (d), 126.21 (s), 125.99 (d), 124.74 (s), 124.41 (d), 123.93 (d), 123.81 (s), 66.88 (t).

(10) Ethyl chloroformate (0.83 g, 7.68 mmol) was added during 15 min to a mixture of 2-hydroxy-1-(pyren-1-yl)ethanone (2.0 g, 7.68 mmol), N,N-dimethylpyridin-4-amine (DMAP) (1.13 g, 9.22 mmol) in dichloromethane (20 mL). After stirring overnight at room temperature, the solvent was evaporated. Column chromatography (SiO.sub.2, ethyl acetate/n-heptane 1:1) afforded 2.12 g (83%) of a yellow solid.

(11) .sup.1H-NMR (500 MHz): 8.96 (d, J=9.3, 1H), 8.20-8.15 (m, 3H), 8.14 (d, J=8.0, 1H), 8.07 (d, J=9.0, 1H), 8.02 (d, J=8.0, 1H), 7.99 (t, J=7.5, 1H), 7.93 (d, J=9.0, 1 H), 5.46 (s, 2H), 4.31 (q, J=7.2, 2 H), 1.37 (t, J=7.1, 3 H).

(12) .sup.13C-NMR (125.8 MHz): 195.55 (s), 155.06 (s), 134.38 (s), 130.85 (s), 130.37 (s), 130.15 (d), 130.00 (s), 129.98 (d), 127.80 (s), 126.87 (d), 126.55 (d), 126.48 (d), 126.34 (d), 125.62 (d), 124.82 (s), 124.42 (d), 123.90 (s), 123.83 (d), 70.03 (t), 64.75 (t), 14.24 (q).

Preparation of (1R,2S,5R)-2-isopropyl-5-methylcyclohexyl (2-oxo-2-(pyren-1-yl)ethyl)carbonate

(13) ()-Menthyl chloroformate (0.84 g, 3.84 mmol, origin: Aldrich) was added during 15 min to a mixture of 2-hydroxy-1-(pyren-1-yl)ethanone (1.0 g, 3.84 mmol), DMAP (0.56 g, 4.61 mmol) in dichloromethane (20 mL). After stirring overnight at room temperature, the solvent was evaporated and the residue taken up with ethyl acetate (50 mL), washed with demineralized tap water (330 mL), dried (Na.sub.2SO.sub.4), concentrated and dried under high vacuum during 2 h to give 1.59 g of a brownish red solid. The compound still contained impurities and was thus re-dissolved in ethyl acetate (50 mL) at 40 C., washed with aqueous HCl (10%, 330 mL), water (30 mL) and a saturated aqueous solution of NaHCO.sub.3 (30 mL). The organic phase was dried (Na.sub.2SO.sub.4), concentrated and dried under high vacuum during 2 h to give 1.11 g (65%) of a brownish yellow solid, still containing some impurities.

(14) .sup.1H-NMR (500 MHz): 8.92 (d, J=9.3, 1H), 8.25-8.19 (m, 3H), 8.19 (d, J=9.6, 1H), 8.13 (d, J=9.0. 1H), 8.11 (d, J=8.0, 1H), 8.03 (t, J=7.5, 1H), 8.01 (d, J=9.0, 1 H), 5.42 (d, J=3.2, 2 H), 4.57-4.49 (m, 1H), 2.07-2.00 (m, 1H), 1.93-1.84 (m, 1H), 1.70-1.57 (m, 2H), 1.50-1.35 (m, 2H), 1.10-0.78 (m, 3H), 0.85 (d, J=6.7, 3 H), 0.81 (d, J=6.7, 3 H), 0.66 (d, J=7.0, 3 H).

(15) .sup.13C-NMR (125.8 MHz): 196.50 (s), 154.78 (s), 134.28 (s), 130.93 (s), 130.48 (s), 130.06 (d), 129.95 (s), 129.93 (d), 128.36 (s), 126.96 (d), 126.50 (2d), 126.33 (d), 125.66 (d), 124.93 (s), 124.46 (d), 124.05 (s), 123.82 (d), 79.25 (d), 70.15 (t), 46.95 (d), 40.52 (t), 34.03 (t), 31.36 (d), 26.02 (d), 23.29 (t), 21.88 (q), 20.59 (q), 16.11 (q).

Preparation of (6-(dimethylamino)quinolin-2-yl)methyl ethyl carbonate

(16) 4-N,N-Dimethylaminoaniline (10.00 g, 73.4 mmol, origin: Alfa Aesar) was dissolved in 6 M aqueous HCl (132 mL). (E)-2-Butenal (10.30 g, 147 mmol, origin: Acros) was added and the mixture stirred at room temperature for 1 h. Then toluene (70 mL) was added and the reaction heated at reflux overnight. After cooling to room temperature, the organic layer was removed. The aqueous layer was treated with NaOH (10%, 350 mL) and extracted with dichloromethane (2100 mL). The organic phase was washed with water (2100 mL) and with a saturated aqueous solution of NaCl (2), dried (Na.sub.2SO.sub.4), and concentrated under reduced pressure. Column chromatography (SiO.sub.2, ethyl acetate) gave 8.44 g (62%) of N,N,2-trimethylquinolin-6-amine as a brown solid.

(17) .sup.1H-NMR (500 MHz): 7.87 (d, J=9.3, 1H), 7.83 (d, J=8.3, 1H), 7.31 (dd, J=9.3, 2.9, 1H), 7.13 (d, J=8.3, 1H), 6.76 (d, J=2.9, 1H), 3.01 (s, 6H), 2.66 (s, 3H).

(18) .sup.13C-NMR (125.8 MHz): 154.54 (s), 148.12 (s), 141.89 (s), 134.43 (d), 129.10 (d), 127.77 (s), 122.11 (d), 119.30 (d), 105.41 (d), 40.78 (q), 24.92 (q).

(19) A solution of N,N,2-trimethylquinolin-6-amine (2.00 g, 10.7 mmol) in dioxane (15 mL) was added to a suspension of selenium dioxide (1.55 g, 14.0 mmol) in dioxane (60 mL) and water (3.4 mL) at 80 C. The mixture was left stirring at 80 C. for 3 h. After cooling to room temperature, the product was filtered on celite, washed with dichloromethane and the filtrate concentrated under reduced pressure. Column chromatography (SiO.sub.2, ethyl acetate/n-heptane 1:3) gave 0.80 g (37%) of 6-(dimethylamino)quinoline-2-carbaldehyde as a brownish-yellow solid.

(20) .sup.1H-NMR (500 MHz): 10.12 (d, J=1.0, 1H), 8.03 (d, J=9.6, 1H), 7.97 (d, J=8.3, 1 H), 7.88 (d, J=8.3, 1H), 7.39 (dd, J=9.3, 2.9, 1H), 6.76 (d, J=2.9, 1H), 3.13 (s, 6H).

(21) .sup.13C-NMR (125.8 MHz): 193.47 (d), 150.17 (s), 148.85 (s), 141.69 (s), 134.21 (d), 132.22 (s), 131.28 (d), 119.70 (d), 118.09 (d), 103.83 (d), 40.37 (q).

(22) 6-(Dimethylamino)quinoline-2-carbaldehyde (0.70 g, 3.5 mmol) was dissolved in ethanol (35 mL) and cooled to 0 C. before sodium borohydride (0.15 g, 3.85 mmol) was added. The solution was stirred for 1 h at room temperature and the reaction followed by TLC. Aqueous HCl (10%, ca. 50 drops) was added dropwise until the solution turned orange.

(23) The solvent was removed under reduced pressure and the residue taken up in dichloromethane (40 mL). The mixture was washed water (230 mL), a saturated aqueous solution of NaCl (2) and dried (Na.sub.2SO.sub.4). The solvent was removed under reduced pressure and the product dried under high vacuum (2 h) to give 0.69 g (98%) of (6-(dimethylamino)quinolin-2-yl)methanol as an orange solid.

(24) .sup.1H-NMR (500 MHz): 7.91 (d, J=8.4, 1H), 7.90 (d, J=9.3, 1H), 7.33 (dd, J=9.3, 2.9, 1H), 7.15 (d, J=8.7, 1H), 6.80 (d, J=2.9, 1H), 4.84 (s, 2H), 4.48 (br. s, 1H), 3.05 (s, 6H).

(25) .sup.13C-NMR (125.8 MHz): 154.74 (s), 148.54 (s), 140.70 (s), 135.01 (d), 129.10 (d), 128.99 (s), 119.40 (d), 118.63 (d), 105.33 (d), 64.15 (t), 40.73 (q).

(26) Ethyl chloroformate (0.27 g, 2.52 mmol) was added during 15 min to a solution of (6-(dimethylamino)quinolin-2-yl)methanol (0.51 g, 2.52 mmol) and DMAP (0.37 g, 3.03 mmol) in dichloromethane (20 mL). The mixture was stirred at room temperature for 4 h, before more ethyl chloroformate (0.2 mL) was added. The mixture turned dark and the reaction was stirred at room temperature for 1 h. The solvent was removed under reduced pressure to give a brownish-orange solid, which was taken up in ethyl acetate (12 mL) and water (2 mL). The mixture was stirred for 30 min, before Na.sub.2SO.sub.4 was added. After filtration, the mixture was concentrated under reduced pressure to ca. 4 mL and n-heptane (1 mL) was added. Column chromatography of the solution (SiO.sub.2, n-heptane/ethyl acetate 1:1) gave 0.28 g (40%) of a brownish-yellow oil.

(27) .sup.1H-NMR (600 MHz): 7.96 (d, J=8.5, 1H), 7.92 (d, J=9.2, 1H), 7.38 (d, J=8.5, 1H), 7.36 (dd, J=9.2, 3.1, 1H), 6.78 (d, J=3.1, 1H), 5.38 (s, 2H), 4.25 (q, J=7.2, 2 H), 3.07 (s, 6H), 1.33 (t, J=7.1, 3 H).

(28) .sup.13C-NMR (151.0 MHz): 155.12 (s), 150.99 (s), 148.72 (s), 141.63 (s), 134.93 (d), 129.75 (d), 129.19 (s), 119.79 (d), 119.64 (d), 104.79 (d), 70.68 (t), 64.27 (t), 40.66 (q), 14.29 (q).

Preparation of ethyl(2-oxo-2-phenylethyl)carbonate

(29) Ethyl chloroformate (8.0 g, 73.6 mmol) was added dropwise to a vigorously stirred solution of 2-hydroxy-1-phenylethanone (5.0 g, 36.8 mmol, origin: Acros) in pyridine (50 g). The reaction was heated at 80 C. for 1 h and left cooling to room temperature for 1 h.

(30) The mixture was poured onto ice and aqueous H.sub.2SO.sub.4 (25%, 200 mL), extracted with diethylether (150 mL), washed with aqueous H.sub.2SO.sub.4 (10%, 100 mL), a saturated aqueous solution of NaHCO.sub.3 (2100 mL) and water (2100 mL). The organic phase was dried (Na.sub.2SO.sub.4) and concentrated under reduced pressure (45 C.) to give 7.1 g of an orange-yellow oil as the crude product. Column chromatography (SiO.sub.2, ethyl acetate/n-heptane 1:3) gave 6.82 g (89%) of an orange-yellow oil.

(31) .sup.1H-NMR (600 MHz): 7.94-7.89 (m, 2H), 7.64-7.59 (m, 1H), 7.52-7.47 (m, 2H), 5.35 (s, 2H), 4.27 (q, J=7.2, 2 H), 1.35 (t, J=7.1, 3 H).

(32) .sup.13C-NMR (151.0 MHz): 191.88 (s), 154.87 (s), 134.02 (d), 128.92 (d), 127.75 (d), 68.51 (t), 64.73 (t), 14.21 (q).

Preparation of (9,10-dioxo-9,10-dihydroanthracen-2-yl)methyl ethyl carbonate

(33) Ethyl chloroformate (0.91 g, 8.39 mmol) was added during 15 min to a mixture of 2-hydroxymethylanthraquinone (2.00 g, 8.39 mmol, origin: Sigma) and DMAP (1.23 g, 10.1 mmol) in dichloromethane (20 mL). After stirring overnight at room temperature, the solvent was evaporated to give a brown paste. Column chromatography (SiO.sub.2, ethyl acetate/n-heptane 3:7) afforded 1.15 g (44%) of a yellow solid.

(34) .sup.1H-NMR (500 MHz): 8.32-8.27 (m, 4H), 7.83-7.77 (m, 3H), 5.31 (s, 2H), 4.26 (q, J=7.2, 2 H), 1.34 (t, J=7.2, 3 H).

(35) .sup.13C-NMR (125.8 MHz): 182.75 (s), 182.67 (s), 154.90 (s), 142.06 (s), 134.22 (d), 134.18 (d), 133.68 (s), 133.45 (s), 133.43 (s), 133.22 (s), 132.91 (d), 127.77 (d), 127.29 (d), 127.25 (d), 126.15 (d), 68.09 (t), 64.56 (t), 14.25 (q).

Example 2

(36) Degradation of Photolabile Compounds Capable of Generating a Gas Upon Exposure to Light

(37) The photolabile compounds capable of generating a gas upon exposure to light according to the invention (0.08 mmol) were each dissolved in acetonitrile (10 mL). An aliquot of this solution (5 mL) was placed inside a Pyrex test tube (14 mL total volume) and closed with a grinded stopper. The solution was then irradiated with a xenon lamp (Heraeus Suntest CPS at about 45000 lux, corresponding to 3.1 mW/cm.sup.2 of UVA-light) for 30 min. High performance liquid chromatography (HPLC) was used to quantify the degradation of the product before and after irradiation. The measurements were carried out on a Thermo Separation Products instrument composed of a SpectraSystem SCM1000 online vacuum degasser, a SpectraSystem P4000 quaternary pump, a SpectraSystem AS3000 autosampler and a SpectraSystem UV6000LP diode array detector. For the analysis, the solution (50 L) was diluted with acetonitrile (950 L) and injected (10 L) onto a Macherey-Nagel Nucleosil 120-5 C4 (2504 mm) column and eluted at 1 mL/min with a gradient of water/acetonitrile (containing 0.1% of trifluoroacetic acid) moving from 50:50 to 20:80 (during 5 min) with UV detection at 254 nm. The results of the measurements are summarized in Table 1; the reported percentages correspond to the relative HPLC peak areas before and after exposure to light for 30 min.

(38) TABLE-US-00001 TABLE 1 Degradation of photolabile compounds in solution upon exposure to light Amount of remaining photolabile compound after Photolabile compound irradiated exposure to light for 30 min Butyrophenone 76% 2-(9-Oxo-9H-xanthen-2-yl)acetic acid 62% ethyl (2-oxo-2-(pyren-1-yl)ethyl) carbonate 85% (6-(Dimethylamino)quinolin-2-yl)methyl 81% ethyl carbonate Ethyl (2-oxo-2-phenylethyl) carbonate 53% together with 9,10-dimethylanthracene (1.2 eq.) as photosensitizer (9,10-Dioxo-9,10-dihydroanthracen- 55% 2-yl)methyl ethyl carbonate

(39) The rate of degradation of butyrophenone was measured by HPLC using the conditions described above. Before irradiation (t.sub.0) a first aliquot of the solution (50 L) was pipetted off, diluted with acetonitrile (950 L) and analyzed. Then the lamp was switched on, and further aliquots of the solutions were pipetted off (every 10 min during 1 h, then every 20 min during another 3 h), diluted and analyzed as described above.

(40) Observed first-order rate constants (k.sub.obs) were obtained according to Equation 1 by plotting the negative natural logarithm of the (decreasing) peak areas measured at time t (A.sub.t) over the one measured at time t.sub.0 (A.sub.0) against time.
A.sub.t=A.sub.0e(k.sub.obst)(Eq. 1)

(41) Linear regression gave a straight line with a correlation coefficient (r.sup.2) of 0.985 and an observed first-order rate constant (k.sub.obs) of 8.8110.sup.5 s.sup.1.

(42) The data show that the photolabile compounds rapidly degrade after exposure to light.

Example 3

(43) Preparation of Microcapsules a According to the Present Invention Containing a Photolabile Compound Capable of Generating a Gas Upon Exposure to Light and a Fragrance Molecule as the Oil Phase

(44) In a beaker, a polyisocyanate (Takenate D-110N, Trimethylol propane-adduct of xylylene diisocyanate, origin Mitsui Chemicals, 2.35 g) and photolabile 1-phenylbutan-1-one (butyrophenone, origin: Aldrich, 8.76 g) were dissolved in Romascone (methyl 2,2-dimethyl-6-methylene-1-cyclohexanecarboxylate, origin: Firmenich SA, 4.38 g) and Hedione HC (methyl 2-((1S,2R)-3-oxo-2-pentylcyclopentyl)acetate, origin: Firmenich SA, 4.39 g). The oil phase was added to a solution of poly(vinyl alcohol) (circa 0.43 g, PVOH 18-88, origin: Aldrich) at 1 wt % in water (circa 42 mL). An emulsion was prepared by Ultra-Turrax stirring (model S25N 10G) between 15000 and 24000 rpm for 2 min. The droplet size was controlled by light microscopy. The emulsion was then introduced at room temperature into a 250 mL reactor and stirred with an anchor at 350 rpm. A solution of guanazole (1H-1,2,4-Triazole-3,5-diamine, origin: Alfa Aesar, 0.43 g) in water (circa 5 mL) was added dropwise onto the emulsion for 1 h. The reaction mixture was heated from room temperature to 70 C. during 1 h at pH 5, and then kept at 70 C. for 2 h, and finally cooled to room temperature to afford a white dispersion.

Comparative Example 3

(45) Preparation of Comparative Microcapsules a without an Invention's Photolabile Compound (Microcapsules According to the Prior Art)

(46) In a beaker, a polyisocyanate (Takenate D-110N, origin Mitsui Chemicals, 3.52 g) and Romascone (8.77 g) were dissolved in Hedione HC (8.75 g). The oil phase was added to a solution of PVOH 18-88 (circa 0.44 g) at 1 wt % in water (circa 42 mL). An emulsion was prepared by Ultra-Turrax stirring (model S25N 10G) between 15000 and 24000 rpm for 2 min. The droplet size was controlled by light microscopy. The emulsion was then introduced at room temperature into a 250 mL reactor and stirred with an anchor at 350 rpm. A solution of guanazole (0.65 g) in water (circa 5 mL) was added dropwise onto the emulsion for 1 h. The reaction mixture was heated from room temperature to 70 C. during 1 h at pH 5, and then kept at 70 C. for 2 h, and finally cooled to room temperature to afford a white dispersion.

Example 4

(47) Release of the Oil Phase from the Microcapsules after Exposure to Light

(48) General Protocol

(49) Dispersions of Microcapsules A and Comparative Microcapsules A, obtained as described in Example 3 and Comparative Example 3, were diluted in water to have the same concentration of fragrance in the oil phase. An aliquot of these dispersions was put onto a glass slide (Table 2) and kept at room temperature in the dark for 96 h. The glass slide was then placed inside a headspace sampling cell (ca. 500 mL of inner volume), and exposed to a constant air flow of ca. 200 mL/min. The air was filtered through activated charcoal and aspirated through a saturated solution of NaCl to give a constant humidity of ca. 75%. Glass slides were irradiated with xenon light (Heraeus Suntest CPS at about 45000 lux), respectively. The evaporated volatiles were adsorbed for 10 min on a clean Tenax cartridge (0.10 g) every 15 min. The cartridges were thermally desorbed on a Perkin Elmer TurboMatrix ATD thermodesorber, injected onto a Agilent Technologies 7890A System gas chromatograph equipped with a HP-1 capillary column and eluted using a temperature gradient starting at 60 C., then heating to 200 C. at 15 C./min. The amount of fragrances released was quantified by external standard calibration. The results obtained for the irradiation of the different samples are summarized in FIG. 1.

(50) TABLE-US-00002 TABLE 2 Composition of dispersion put on glass slide for headspace analysis Mass of Mass of Concentration of Dispersion dispersion [g] water [g] volatile (wt %) Comparative Example 0.100 5.000 0.513 3 (Prior art) Example 3) 0.101 5.310 0.504

(51) The data in FIG. 1 demonstrate that considerably higher headspace concentrations of perfume oil were measured in the headspace above Microcapsules A containing photolabile butyrophenone according to the invention as compared to an equivalent prior art microcapsule. In addition, before exposure to light the headspace concentration of perfume oil released from Microcapsule A of the present invention was as low as the headspace concentration of perfume oil released from microcapsules of the prior art. The exposure to light initiated the degradation of the butyrophenone by forming a gas and, as a consequence, triggered the release of the perfume oil (concentrations before and after the arrow in FIG. 1). The presence of a gas-generating photolabile compound according to the invention is thus suitable to efficiently trigger the release of an encapsulated oil phase without requiring scratching or rubbing the microcapsules to mechanically break their shell.