Fragrance precursors

Details Fragrance precursors Fragrance precursors

2001-04-10

2002-12-10

Wilson, James O. (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Oxygen containing

C568S328000, C568S329000, C568S331000, C568S337000, C568S376000, C568S377000

Reexamination Certificate

active

06492563

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to fragrance precursors for a fragrant ketone and a fragrant ester. Compositions containing such fragrant precursors are also provided. A process for imparting a fragrance to a substrate using such a fragrance precursor is also provided.
BACKGROUND OF THE INVENTION
A principal strategy currently employed in imparting odors to consumer products is the admixing of the fragrance directly into the product. There are, however, several drawbacks to this strategy. The fragrance material can be too volatile and/or too soluble, resulting in fragrance loss during manufacturing, storage, and use. Many fragrance materials are also unstable over time. This again results in loss during storage.
In many consumer products it is desirable for the fragrance to be released slowly over time. Microencapsulation and inclusion complexes with cyclodextrins have been used to help decrease volatility, improve stability and provide slow-release properties. However, these methods are, for a number of reasons, often not successful. In addition, cyclodextrins can be too expensive.
Precursors for the delivery of organoleptic compounds, especially for flavors, fragrances and masking agents are described in EP-A 0 936 211. This delivery system releases one or more odoriferous compounds upon exposure to light and/or UV irradiation. Using this system in various consumer products leads to a prolonged perception of the fragrant compound(s) to be released.
WO 99/60990 describes fragrance precursors which release fragrant alcohols, aldehydes or ketones upon exposure to light. Perfuming compositions containing these fragrance precursors can be used in various consumer products such as detergents, fabric softeners, household products, hair care products, etc.
It is known that phenacyl glycosides undergo a Norrish Type II photoreaction leading to gluconolactones and the corresponding phenacyl compound (Crich et al., Tetrahedron, 1995, 51, 11945-11952). However, it has not been described or suggested to use such phenacyl acetals as fragrance precursors, which are capable of releasing a fragrant ketone and a fragrant ester over a prolonged period.
Many fragrant compounds with odors accepted by the public are esters of high volatility resulting in a short period of perceivable odor. Such esters are quickly hydrolyzed in an alkaline environment, thereby losing the fragrant characteristic. Therefore, they are of limited use for laundry products.
SUMMARY OF THE INVENTION
It is therefore desirable to have a fragrance delivery system which is capable of releasing the fragrant compound or compounds in a controlled manner, while maintaining a desired odor over a prolonged period of time.
An object of the present invention is to provide non-volatile precursors for volatile fragrant esters.
Another object of the present invention is to provide fragrance precursors which are stable in an alkaline environment, especially in laundry products.
A further object of the present invention is to provide fragrance precursors with high substantivity.
Another object of the present invention is to provide fragrance precursors which are activated and cleaved by light.
A further object of the present invention is to provide fragrance precursors with slow release properties.
Accordingly, one embodiment of the invention is a fragrance precursor of formula I:
for a fragrant ketone of formula II:
and a fragrant ester of formula III:
wherein,
R
1
to R
5
represent independently H, —NO
2
, linear or branched C
1
-C
6
-alkyl, C
1
-C
6
-alkenyl, C
1
-C
6
-alkinyl, or C
1
-C
4
-alkoxy,
R
6
and R
7
are independently H, linear or branched C
1
-C
6
-alkyl-, C
1
-C
6
-alkenyl, or C
1
-C
6
-alkinyl,
R
8
and R
9
are the residues of an acid R
8
-COOH and an alcohol R
9
OH respectively forming the fragrant ester of formula III.
Another embodiment of the invention is a composition containing a base and a fragrance precursor of formula I:
that upon exposure to light forms a fragrant ketone of formula II:
and a fragrant ester of formula III:
wherein,
R
1
to R
5
represent independently H, —NO
2
, linear or branched C
1
-C
6
-alkyl, C
1
-C
6
-alkenyl, C
1
-C
6
-alkinyl or C
1
-C
4
-alkoxy,
R
1
and R
2
, R
2
and R
3
, R
3
and R
4
, and R
4
and R
5
may form together one or two aliphatic or aromatic rings,
R
6
and R
7
are independently H, linear or branched C
1
-C
6
-alkyl-, C
1
-C
6
-alkenyl, C
1
-C
6
-alkinyl, and
R
8
and R
9
are the residues of an acid R
8
-COOH and an alcohol R
9
OH respectively forming the fragrant ester of formula III.
A further embodiment of the invention is a process for providing a fragrance to a substrate having the steps of:
(a) contacting a substrate with a composition comprising fragrance precursor of formula I:
wherein,
R
1
to R
5
represent independently H, —NO
2
, linear or branched C
1
-C
6
-alkyl, C
1
-C
6
-alkenyl, C
1
-C
6
-alkinyl or C
1
-C
4
-alkoxy,
R
1
and R
2
, R
2
and R
3
, R
3
and R
4
,and R
4
and R
5
may form together one or two aliphatic or aromatic rings,
R
6
and R
7
are independently H, linear or branched C
1
-C
6
-alkyl-, C
1
-C
6
-alkenyl, C
1
-C
6
-alkinyl, and
R
8
and R
9
are the residues of an acid R
8
—COOH and an alcohol R
9
OH respectively forming the fragrant ester of formula III; and
(b) exposing the substrate to light source, to form a fragrant ketone of formula II:
and a fragrant ester of formula III:
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to fragrance precursors of formula I:
which upon exposure to light, and in particular daylight, release a fragrant ketone of formula II:
and a fragrant ester of formula III:
wherein
R
1
to R
5
represent independently H, —NO
2
, branched or linear C
1
-C
6
-alkyl, C
1
-C
6
-alkenyl, C
1
-C
6
-alkinyl, or C
1
-C
4
-alkoxy,
R
1
and R
2
, R
2
and R
3
, R
3
and R
4
, and R
4
and R
5
may form together one or two aliphatic or aromatic rings, these rings may optionally contain branched or linear C
1
-C
4
-alkyl, C
1
-C
4
-alkenyl, or C
1
-C
4
-alkinyl residues, and the above rings and residues may contain one or more oxygen atoms,
R
6
and R
7
are independently H, branched or linear C
1
-C
6
-alkyl, C
1
-C
6
-alkenyl, or C
1
-C
6
-alkinyl, and R
6
or R
7
may form with either R
1
or R
5
a carbocyclic ring optionally substituted by an aliphatic residue.
R
8
and R
9
are the residues of an acid R
8
—COOH and an alcohol R
9
OH respectively forming the fragrant ester of formula III.
The branched carbon chains defined above also may have multiple branched chains.
The fragrance precursors of formula I release, upon exposure to light, volatile fragrant esters of formula III and fragrant ketones of formula II. Because the precursors of the invention are stable in an alkaline environment, and show high substantivity, they are well adapted for detergent and laundry use.
The fragrance precursors of the present invention are slowly cleaved when exposed to light, in particular daylight. Upon absorption of energy from the light, the phenacyl acetals of formula I undergo a Norrish Type II photoreaction, which leads to the release of a fragrant ketone of formula II and a fragrant ester of formula III.
The release of the above mentioned fragrant compounds occurs, for example, upon exposure to a UV radiation source, such as sunlight penetrating through ordinary windows, although the light need not be particularly rich in UV irradiation. Upon exposure to bright sunlight, in particular direct sunlight from the outdoors, the release of the fragrant compounds of formula II and III will occur faster and to a greater extent than upon exposure to room light inside a building. The cleavage of the precursors of the present invention can also be initiated by an appropriate lamp, for example, a sun tanning lamp.
The photoreaction of the fragrance precursors of formula I involves, in a first step, the absorption of light by the keto-group followed by abstraction of the acetal-H atom and subsequent cleavage of the resulting 1,4-diradical (Scheme A). It has been found that the aromat

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