A NEW DEPILATORY ACTIVE, IT'S PROCESS OF PREPARATION AND
COMPOSITION THEREOF

FIELD OF INVENTION

[001] The embodiments herein generally relate to a depilatory composition, and more particularly to a new depilatory active, a process for preparation of the depilatory active compound and a depilatory composition which helps in hair care.

BACKGROUND AND PRIOR ART

[002] Methods of hair removal have been known for centuries. Earlier, extracts of plants were used that contained chemical substances that aided in removing hair. The earliest recorded use of such hair removers is found in ancient India where abrasive pastes and resinous plasters were frequently used to physically remove hair. In the Middle East, a lime mixture was used for a similar purpose. Other materials, such as antimony and arsenic compounds, were also used; however, many of these naturally occurring chemical depilatories or abrasive pastes were quite harsh on the skin, leading to irritation. Some were even toxic and were frequently malodorous as well.

[003] One of the earliest known hair removal techniques is epilation, or physically pulling hair out. Common procedures included using devices like tweezers to pull hair out selectively or waxes which pulled hair out in large masses.

[004] Epilating Wax is still used by cosmeticians and other professionals. Epilating waxing involves the application of heated flowable wax to the desired skin area. The wax is allowed to cool and harden and is then stripped off from the skin by pressing paper,

pulling the hair by its roots. This procedure can effectively remove 80% of the hair from a desired skin area. However, the procedure involved is quite painful, and it, many a times leads to skin irritation. Therefore, mild anti-septics are used after the hair is removed. Also, waxing is not favored so much by individual consumers as by professional salons since the method involved is complicated. There also remains the problem of storage as most often the unrefined sugar used in the formulation tends to harden over time.

[005] Since hair removal by physical means is often a painful experience, scientists worked on developing formulas, which would chemically remove hair. These are quite common in personal care and are known as depilatories. Depilatories rely on a chemical reaction between materials in the formula with keratin of the hair.

[006] Probably the most widely used depilatory agents developed in modern times are commercially-sold creams and ointments which contain as their active ingredient disulfide bond breakers such as salts of mercaptan acids, particularly salts of thioglycolic acid.

[007] These salts attack the most recently formed portion of the hair shaft, that is, the part closest to the skin surface. They act by rupturing the disulfide bonds in the keratin protein found in the hair shaft, weakening the hair and causing it to be ruptured at the surface of the skin. The hair is weakened to such an extent that merely scraping or wiping the cream off the skin breaks the hair at skin level and thus removes it. The hair root, however, remains in the follicle and the disulfide bond breaking salts have a deleterious effect on the skin and give rise to unpleasant odors. Since the cream includes a substance that degrades hair keratin, such substances tend to irritate the skin, which is a problem for users with sensitive skin. Compositions with reduced irritancy have been sought.

[008] Sulfides and thioglycollates are the most commonly used depilatory actives. Little progress was made in this area until about 100 years ago when it was first reported that barium sulfide was used for this purpose. A few years later a similar idea was patented in the United States. Cream depilatories were first introduced in the 1920s and many more patents were issued during the 1930s. Thioglycollate depilatories, which were first introduced in 1938, have become the most important hair removers.

[009] Sulfides such as barium sulfide, strontium sulfide and calcium sulfides are used because they react more rapidly than thioglycollates. However, their use is limited because of the formation of hydrogen sulfide, which has a very unpleasant odour, during wash off. The toxicity levels of organic sulfides are also very high.

[0010] Thioglycollate salts include materials such as calcium thioglycollate, potassium thioglycollate, sodium thioglycollate and lithium thioglycollate. The use of thiol-based depilatory agents, such as thioglycolic acid salts, for removal of unwanted body and facial hair is well established in the art. In an aqueous solution at the proper pH, they are converted to acids, which then affect the hair. But the skin irritation they are likely to produce is their biggest disadvantage.

[0011] Though the calcium thioglycollate has been widely used and proved to be less irritating to the skin even during longer contact times, it tends to form crystals in formulation during the storage.

[0012] Therefore, there is a need for providing a depilatory composition which may overcome one or more disadvantages of the prior art depilatory compositions including unpleasant odor during rinsing, high toxicity, skin irritation, skin redness, skin roughness, skin dryness and it may be possible to avoid use of additional moisturizer.

OBJECTS OF THE INVENTION:

[0013] One object is to provide a new chemical compound which is an effective depilatory active.

[0014] Another object is to provide a depilatory active and a process for preparing the depilatory active, which is a Thioglycolic acid ester of a Biomass derived compound and bio-degradable.

[0015] Yet another object is to provide a depilatory active which has moisturizing property, not found in present depilatory actives.

[0016] Still another object is to provide a depilatory composition which does not cause any irritation or redness to the skin when applied.

[0017] Another object is to provide a depilatory composition which does not give unpleasant odor.

[0018] Yet another object is to provide a depilatory composition which is not toxic.

[0019] The other objects and advantages of the present invention will be apparent from the following description when read in conjunction with the accompanying drawings which are incorporated for illustration of preferred embodiments of the present invention and are not intended to limit the scope thereof.

SUMMARY OF THE INVENTION:

[0020] In view of the foregoing, the embodiment herein provides a process for producing a hitherto unknown depilatory active and employing the active in preparing a depilatory cream composition, which helps in effective hair care, wherein the term "hair care"

includes hair removal (depilation), significantly reducing the re-growth of hair, hair
weakening or softening, shaping etc.

[0021] According to an embodiment, the process for preparing the depilatory active comprises a chemical reaction of isosorbide [also referred as Dianhydro Sorbitol] with Thioglycolic acid in the presence of an acid catalyst.

[0022] According to an embodiment, a depilatory cream composition comprising a depilatory active, namely Isosorbide thioglycollate in an amount less than 10% by weight of the composition.

[0023] In an embodiment, the depilatory active is an Isosorbide monothioglycollate. In another embodiment, the depilatory active is an Isosorbide dithioglycollate.

[0024] In an embodiment, a method of depilation is provided comprising the steps of
firstly applying the depilatory composition to the skin, wherein the depilatory
composition comprising of depilatory active compound, Isosorbide thioglycollate,
thereafter allowing the composition to reside on the skin for a predetermined time to
depilate hairs followed by removing the composition and depilated hairs from the skin
and rinsing of the skin with water.

[0025] These and other aspects of the embodiments herein will be better appreciated and
understood when considered in conjunction with the following description and the
accompanying drawings. It should be understood, however, that the following
descriptions, while indicating preferred embodiments and numerous specific details
thereof, are given by way of illustration and not of limitation. Many changes and
modifications may be made within the scope of the embodiments herein without
departing from the spirit thereof, and the embodiments herein include all such

modifications.
DETAILED DESCRIPTION OF EMBODIMENTS

[0026] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.

[0027] The embodiments herein achieve the object of preparing a new depilatory active wherein the disadvantages observed in the prior art are eliminated or greatly reduced, wherein a specific chemical reaction for producing the hitherto unknown effective depilatory actives are disclosed.

[0028] This disclosure is directed to a chemical reaction for creating a new depilatory active. More particularly, the disclosure is directed to a chemical reaction which deals with the esterification of the chemical compound, Dianhydro Sorbitol with Thioglycolic acid in the presence of an acid catalyst to produce new depilatory active compounds. Additionally, a preparation of a depilatory composition using the same depilatory active and a method of depilation of the depilatory composition are also disclosed.

[0029] Biomass derived compounds such as sugar alcohols and their dehydrated products

are known useful polyols. In particular are, the bicyclic ether derivatives known as bis
anhydro hexitols , made by doubly dehydrating hexitols such as Sorbitol and Mannitol to
Isosorbide and Isomannide. Their alkyl and aryl esters are commercially interesting
derivatives with highly diverse applications. Sorbitan esters are used as emulsifiers and
isosorbide esters are used as lubricants, preservatives, dispersing agents and plasticizers
etc.

[0030] An embodiment of the present invention relates to the preparation of a thioglycolic
acid ester of dianhydro sorbitol which makes it a more efficient depilatory active.

[0031] In an embodiment of the present invention, the depilatory active is synthesized by
acid catalysed esterification of Dianhydro Sorbitol with Thioglycolic acid in presence of a
suitable Lewis acid catalyst such as Sulphuric acid, p-Toluene sulphonic acid, Methane
chloro sulphonic acid etc.

[0032] The exemplary procedure for obtaining the hitherto unknown chemical, Dianhydro
Sorbitol Thioglycollate, [also referred as Isosorbide Thioglycollate], involves the mixing of
Dianhydro Sorbitol and Thioglycolic acid wherein the molar ratio of Thioglycolic acid to
Dianhydro Sorbitol is selected between 1 and 4. p-Toluene sulphonic acid is used as the
acid catalyst. The mixture of Dianhydro Sorbitol (1.0 mole), Thioglycolic acid (1-4
mole) and p-Toluene sulphonic acid is stirred in a suitable solvent at a constant reaction
temperature. The reaction temperature is usually between 120 deg C and 180 deg C.

[0033] Once the reaction is complete, solvent is removed and the crude ester obtained is
purified by conventional methods to a pale yellow transparent viscous liquid.

[0034] By varying reaction conditions one can get the mono Thioglycollate, a hitherto a
un-known chemical which is also a hair care active.

[0035] The reaction scheme of Dianhydro Sorbitol dithioglycollate is as follows:

[0036] Accordingly, the depilatory active thus produced is not an inorganic salt but is an
ester of a biomass derived compound.

[0037] It is observed that the depilatory active thus formed by following the chemical
reaction has a good moisturizing effect on the skin and hence, no further addition of
moisturizing agent is required in the composition.

[0038] In one embodiment of the present invention, in order to prepare the depilatory
cream composition comprising the depilatory active Dianhydro sorbitol Thioglycollate, the
active is typically present in an amount less than 10% weight of the composition.

[0039] The novel depilatory cream composition may optionally include a variety of conventional additives and adjunct ingredients commonly used in the art of formulating such compositions. These optional ingredients may include, but not limited to, skin feel enhancing agent like PPG 15 stearyl ether, silk amino acids; suitable surfactants like cetearyl alcohol, cetostearyl alcohol and/or ceteareth 20; a humectant such as urea or propylene glycol; emollients such as cetyl alcohol, liquid paraffin or white soft paraffin, fillers such as magnesium trisilicate and TiCh; buffering agents such as sodium silicate; emulsifying agents such as polawax GP 200, viscosity increasing agents such as acrylate or methacrylate copolymers; emulsion stabilizers such as stearyl and cetearyl alcohol and mixtures containing the same; pH adjusters such as potassium or calcium hydroxide; chelating agents or preservatives such as tetrasodium EDTA, an accerator, etc. Fragrance, color, lubricants, propellants and other additives may be utilized as deemed necessary in accordance with conventional practices in the cosmetics and toiletries industries.

[0040] The following table illustrates a typical depilatory cream composition:


Table 1

[0041] The ingredients labeled "y" were mixed together at a temperature of approximately 60 degrees C to 80 degrees C. The mixture was then cooled and a pre-mix containing ingredients "x" was added at a temperature of approximately 40 degrees C to 60 degrees C. The resulting mixture was agitated further and then cooled. A pre-mix of ingredients "z" was then added at a temperature of approximately 40 degrees C to 60 degrees C, together with the TiO2, Isosorbide thioglycollate and potassium hydroxide.

[0042] The compositions can be formulated using standard techniques known to the person skilled in the art.

[0043] According to an embodiment of the present invention, a method of application of the depilatory cream composition comprising the steps of: applying the composition to the skin surface of the hairy area to form a coating, wherein said composition comprising of depilatory active Isosorbide thioglycollate; allowing the composition a residence time on the skin, typically 5-15 minutes, in order to let the depilatory active degrade the hair shafts on the skin's surface; and removing the composition and the depilated hairs from the skin.

[0044] The main advantage of the present invention is the depilatory active Isosorbide thioglycollate used in the depilatory cream composition did not cause redness or irritation on the skin on the subjects tested and also has a good moisturizing effect on the skin, such that no additional moisturizing complex is required to use in the cream composition.

[0045] Another advantage of the present invention is that the depilatory cream composition thus produced leaves the skin feeling soft and smooth without any skin irritation, on the subjects tested.

[0046] Accordingly, the depilatory active thus produced is not an inorganic salt but an ester of a biomass derived compound and bio-degradable.

[0047] Further the depilatory active and the depilatory composition as disclosed herein does not have the strong unpleasant odor.

[0048] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and therefore, such adaptations and modifications should are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the appended claims.

We Claim:
1.A process for the preparation of a depilatory active comprising of esterification of
Dianhydro Sorbitol with Thioglycolic acid in presence of acid catalyst in a suitable
solvent.

2.The process as claimed in claim 1, wherein said acid catalyst is a Lewis acid catalyst.

3.The process as claimed in claim 1, wherein the molar ratio of said Thioglycolic acid to
said Dianhydro Sorbitol is selected between 1 and 4.

4.The process as claimed in claim 1, wherein the reaction is carried out at a temperature
between 120°C and 180°C.

5.The process as claimed in claim 1, wherein said depilatory active is an Isosorbide
dithioglycollate.

6.The process as claimed in claim 1, wherein said depilatory active is an Isosorbide
monothioglycollate.

7.A depilatory active used for the preparation of depilatory composition, wherein said
depilatory active is an Isosorbide thioglycollate.

8.A depilatory composition as claimed in claim 7, wherein said composition is a cream.

9.The depilatory composition as claimed in claim 7, wherein said Isosorbide
thioglycollate is prepared according to claim 1.

10.The depilatory composition as claimed in claim 7, wherein said depilatory active
present in an amount less than 10% by weight of the composition.