Insect repellents

Details Insect repellents Insect repellents

2001-05-29

2003-12-09

Levy, Neil S. (Department: 1616)

Drug, bio-affecting and body treating compositions

Preparations characterized by special physical form

Biocides; animal or insect repellents or attractants

C424S043000, C424S047000, C424S059000, C424S065000, C424S069000, C424S070100, C424S078310, C424SDIG001, C514S460000, C514S532000, C514S617000, C514S675000, C514S690000, C514S692000, C514S693000, C514S699000, C514S715000, C514S717000, C514S718000, C514S750000, C514S763000, C514S766000, C514S919000, C510S101000

Reexamination Certificate

active

06660288

ABSTRACT:

FIELD OF INVENTION
The present invention relates to the use of certain perfume ingredients as an insect repellent, to compositions containing the perfume ingredients and to a method of repelling insects.
BACKGROUND
Insects have long been known as a nuisance and, for some insect genera, as a health hazard. Mosquitoes, for instance, are a proven vector of diseases, and the genus Aedes in particular is associated with yellow fever, dengue, encephalitis and malaria (Encyclopaedia Britannica). Although the problems may be reduced at source with the use of DDT and other chemical sprays in the breeding areas, fears over the persistence of chlorchemicals combined with increasing mosquito resistance to control chemicals (e.g. insecticides) have led to a reappraisal of the magnitude of the nuisance and the hazard. Physical barriers to the insects are not always possible, e.g. in the open air, where some form of personal repellent is necessary.
It is also a feature of recent times that the more environmentally-aware public tend to question the safety of many chemicals which were formerly taken for granted. One of these is the well-known personal insect repellent N,N-diethyl-m-toluamide (abbreviated as DEET, and commercially available as Delphone™). This was originally seen as the natural successor to the parent molecule, N,N-diethylbenzamide which was found to be strongly insect repellent but also irritating to human skin (McCabe et al., (1954), J. Org Chem. 19, 493-498). Fears over possible allergenicity, disclosed in European Patent Application EP-A-0 167 266 (Angus Chemical Company), as well as aversion to some of the physical properties of this compound such as oiliness and odour, have led to the search for less hazardous and more aesthetically acceptable methods of repelling insect pests, particularly mosquitoes.
REVIEW OF THE PRIOR ART
Certain compounds have long been known to possess insect deterrent properties, some of this information coming from what might be termed “folk knowledge”. These materials include widely-known substances such as Citronella, Tolu and Peru Balsams, Eucalyptus oils, Huon Pine and other similar oils [M. Bouvier, International Frag. Co-ord. 29 October 1976]. Other materials known for their deterrent properties include those having camphoraceous odours, such as Camphor itself, Cypress oils, Galbanum etc. [H&R Contact, 36, 1984].
Perfume ingredients with insect repellent properties used either alone, or in a perfume composition, and/or in some form of carrier or base overcome many of the problems highlighted above. Many common types of household insects such as American cockroaches (
periplaneta americana
) are classified as pests and significant effort has been made to control or eradicate them. A variety of chemicals that are effective in repelling cockroaches has been discovered. These chemicals are used in the household by applying or spraying them to surfaces of walls, floors, cabinets, containers, rugs, upholstery and carpeting, and in potential nesting places for insects, such as inside walls and between floors. They have been used together with hardsurface cleaners (EP-A-0 619 363) and wax floor polishes (U.S. Pat. No. 3,018,217).
It is known in the art that organic materials and essential oils can be repellent against insects. In the art this has been measured in a variety of ways with different insects. The majority of the prior art has been directed towards mosquitoes and in particular the species
aedes aegyptii
. The results of these studies has led to a list of preferred materials. Surprisingly we have found that additional perfume ingredients, preferably when used above certain limits in perfume compositions can lead to enhanced insect repellency.
PCT Application WO 96/08147 discloses the use of a number of different compounds as insect repellents and also a method by which the repellency of compounds to insects can be reliably tested.
SUMMARY OF THE INVENTION
It has now been surprisingly found that a number of perfume ingredients are effective insect repellents.
Accordingly, the present invention provides the use of at least one perfume ingredient selected from the group consisting of
Citral diethyl acetal (Citrathal*),
Tricyclodecenyl allyl ether (also known as 8-(allyloxy)tricyco [5.2.1.0.
2.6
]dec-3-ene) [Fleuroxene*],
2-(2-methylpropyl )-4-hydroxy4-methyltetrahydropyran [Florosa*],
N-methyl-N-phenyl-2-methylbutanamide [Gardamide*],
4-isobutyrate-3-methoxybenzaldehyde [Isobutavan*],
1 -hydroxy-2-methoxy4-propenylbenzene [Isoeugenol*],
2,2,7,7-tetramethyltricyclo[6.2.1.0
1.6
]undecan-5-one [Isolongifolanone*],
7-formyl-5-isopropyl-2-methylbicyclo[2.2.2]oct-2-ene [Maceal*],
3-methyl-5-phenyl-1-pentanal [Mefranal*],
alpha iso methyl ionone (also known as 4-(2,6,6-trimethyl-2-cyclohexen-1 -yl)-3-methyl-3-buten-2-one),
myrcenyl acetate (also known as 2-methyl-6-methylene-7-octen-2-yl acetate) [Neobergamate*],
10-isopropyl-2,7-dimethyloxaspiro [4.5] 3,6-decadiene [Neocaspirene*],
tricyclo[5.2.1.0
2.6
]dec4-en-8-yl 2,2-dimethylpropanoate (Pivacyclene*),
2-phenylethyl pivalate (also known as phenylethyl-2,2-dimethylpropanoate) [Pivarose*]
and 2,4-dimethyl-4-phenyltetrahydrofuran [Rhubafuran*]
as an insect repellent. (*trade marks)
In another aspect, the invention provides a method of repelling insects from an object or an airspace, comprising application to the object or into the airspace, of an effective amount of at least one perfume ingredient selected from the group consisting of the aforementioned perfume ingredients. Typically, the object is a human body or a solid surface such as a wall or floor.
The perfume ingredients from the aforementioned list which are more effective as insect repellents are those which have an octanol-water partition coefficient such that “log P” has a value in the range from 1.0 to 6.0, more preferably 2.0 to 5.0, and particularly 2.5 to 4.5. “log P” is the common logarithm of the octanol-water partition coefficient and is well known in the literature as an indicator of hydrophobicity and water solubility (see Hansch and Leo, Chemical Reviews, 526 to 616 (1971), 71 and Hansch, Quinlan and Lawrence J. Organic Chemistry, 347 to 350 (1968), 33). Where such values are not available in the literature they may be measured directly or approximately estimated using mathematical algorithms. Software providing such estimates is available commercially, for example ‘LogP’ from Advanced Chemistry Design Inc.
In addition, those perfume ingredients which are more effective as insect repellents have a “Kovats” index value in the range from 1150 to 1650, more preferably 1250 to 1600, and particularly 1300 to 1560. Kovats indices are calculated from the retention time in a gas chromatographic measurement referenced to the retention time for alkanes (see Kovats, Helv. Chim. Acta 41, 1915 (1958)). Indices based on the use of a non-polar stationary phase have been used in the perfumery industry for some years as a descriptor relating to the molecular size and boiling point of ingredients. A review of Kovats indices in the perfume industry is given by T Shibamoto in “Capillary Gas Chromatography in Essential Oil Analysis”, P Sandra and C Bicchi (editors), Huethig (1987), pages 259 to 274. A common non-polar phase which is suitable is 100% dimethyl polysiloxane, as supplied, for example, under a variety of trade names such as HP-1 (Hewlett Packard), CP Sil 5 CB (Chrompak), OV-1 (Ohio Valley) and Rtx-1 (Restek).
A further property of the aforementioned perfume ingredients which confers good performance as an insect repellent is a capability of forming hydrogen bonds of greater than 60 on the Koppel Pal'm scale (J. Chem. Soc. Perkin Trans. 2, 1976, pp 1628).
The insect repellent perfume ingredients described herein are preferably used in a composition, more preferably in a perfume composition, preferably at a concentration of at least 10%, more pr

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