WO2012148480A1

WO2012148480A1 - Antiperspirant active compositions and manufacture thereof

Info

Publication number: WO2012148480A1
Application number: PCT/US2011/066012
Authority: WO
Inventors: John Vaughn; Iraklis Pappas; Long Pan
Original assignee: Colgate-Palmolive Company
Priority date: 2011-04-26
Filing date: 2011-12-20
Publication date: 2012-11-01
Also published as: RU2013152264A; EP2702007B1; US9408789B2; AR086119A1; CL2013003094A1; BR112013027593A2; CA2834132A1; MX2013012366A; GT201300261A; US20170128330A1; AU2011366870B2; MX347432B; US20160106643A1; CO6801701A2; CA2834132C; RU2567941C2; ZA201307191B; EP2702007A1; US9717663B2; AU2011366870A1

Abstract

An antiperspirant active composition comprising an aluminum salt, the aluminum salt (i) having an aluminum to chloride molar ratio of 0.3:1 to 3:1; and (ii) having a species of polyhydroxyoxoaluminum cation detectable at 76 ppm by ²⁷Al NMR that is present in a relative abundance on a ²⁷Al NMR spectrograph that is greater than any other polyhydroxyoxoaluminum cation detectable by ²⁷Al NMR. Also, disclosed are methods of making the antiperspirant active.

Description

ANTIPERSPIRANT ACTIVE COMPOSITIONS AND MANUFACTURE THEREOF CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Application No. 61/479,069, filed on 26 April 2011, which is incorporated herein by reference.

FIELD OF THE INVENTION

[0002] The invention relates to antiperspirant active compositions comprising an aluminum salt and to methods of making an antiperspirant active composition.

BACKGROUND OF THE INVENTION

[0003] Antiperspirant salts, such as aluminum chlorohydrex (also called aluminum chlorohydrex polymeric salts and abbreviated here as "ACH") and aluminum zirconium glycine salts

(abbreviated here as "ZAG", "ZAG complexes" or "AZG"), are known to contain a variety of polymeric and oligomeric species with molecular weights (MW) of 100 Da - 500,000 Da. It has been clinically shown that, in general, the smaller the species, the higher the efficacy for reducing sweat.

[0004] In an attempt to increase the quality and quantity of smaller aluminum and/or zirconium species, a number of efforts have focused on: (1) how to select the components of ACH and ZAG that affect the performance of these materials; and (2) how to manipulate these components to obtain and/or maintain the presence of smaller types of these components. These attempts have included the development of analytical techniques to identify the components. Size exclusion chromatography ("SEC") or gel permeation chromatography ("GPC") are methods frequently used for obtaining information on polymer distribution in aluminum salt solutions. With appropriate chromatographic columns, generally five distinctive groups of polymer species can be detected in commercial ACH and ZAG complexes appearing in a chromatogram as peaks 1, 2, 3, 4 and a peak known as "5,6", referred to hereinafter as Peak 5. Peak 1 contains the larger Zr species (greater than 60 Angstroms). Peaks 2 and 3 contain larger aluminum species. Peak 4 contains smaller aluminum species (aluminum oligomers, or small aluminum clusters) and has been correlated with enhanced antiperspirant efficacy for both Al and Al/Zr salts. Peak 5 contains the smallest and most acidic aluminum species. Various analytical approaches for characterizing the peaks of ACH and various types of ZAG actives are found in "Antiperspirant Actives—Enhanced Efficacy Aluminum-Zirconium-Glycine (AZG) Salts" by Dr. Allan H. Rosenberg (Cosmetics and Toiletries Worldwide, Fondots, D. C. ed., Hertfordshire, UK: Aston Publishing Group, 1993, pages 252, 254-256).

[0005] Attempts to activate antiperspirant salts to produce materials having improved efficacy have included developing processes for obtaining composition having large amounts of Peak 4.

[0006] The Applicant's earlier WO-A- 2009/076591 discloses, inter alia, an antiperspirant composition having a composition with little or no Peak 3 and optionally little or no Peak 5. However, there is still a need for yet further improved antiperspirant compositions.

[0007] Solutions of partially neutralized aluminum are known to contain a variety of hydro lytic Al species. The identity and distribution of these various forms depends on the hydrolysis ratio (i.e. the OH:Al molar ratio), the Al precursor and the choice of the reaction condition. In the field of antiperspirant (AP) technology, SEC chromatography is the traditional method used for elucidating the distribution of these Al species. Conventional SEC physically separates Al species into domains which are subsequently measured using a concentration detector. It is generally recognized that at least five domains of Al species can be differentiated by size- exclusive chromatography. These domains are commonly referred to Peak 1, Peak 2, Peak 3, Peak 4, and Peak 5, where increasing peak number indicates smaller relative size of the eluting species. Peak 4 and Peak 5 have been implicated as highly efficacious Al domains for antiperspirants. Monomeric Al and low oligomers, are known to elute under Peak 5. Oligomeric polyhydroxyoxoaluminum cations elute under Peak 4.

[0008] It is well known in the art that such a variety of hydro lytic Al species exists and that it is possible to distinguish large aqueous aluminum hydroxide molecules using spectroscopic methods such as 27 Al NMR which elucidates the structural environment surrounding Al atoms which are embodied in various forms (Casey WH, "Large Aqueous Aluminum Hydroxide Molecules", Chem. Rev. 2006, 106 (1), pages 1 to 16).

[0009] There are two regions in a 27 Al NMR spectrum that represent Al nuclei which are octahedrally coordinated (0 ppm - 60 ppm) and tetrahedrally coordinated (60 ppm - 90 ppm). The octahedral region is exemplified by the hexa-aqua Al species, i.e. monomeric Al, which resonates sharply at 0 ppm. The tetrahedral region is exemplified by sharp resonance at 62.5 ppm from the AI13 polyhydroxyoxoaluminum cation. AI13 is composed of 12 octahedrally coordinated Al atoms surrounded by one centrally-cited Al atom which is tetrahedrally coordinated. The AI30 polyhydroxyoxoaluminum cation is essentially a dimer of the AI13 polyhydroxyoxoalummum cation and contains 2 tetrahedrally coordinated Al atoms which resonate at 70 ppm.

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[0010] It is known that Al NMR spectroscopy may not fully elucidate the chemical

composition of a partially neutralized Al salt solution, since there may be a variety of Al species that do not give rise to sharp and unambiguous resonance peaks. These species can be considered

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as effectively NMR-invisible. Unless the Al NMR spectroscopy is carried out quantitatively, the relative concentration of these NMR-invisible species cannot be determined and must be inferred from SEC chromatography.

[0011] The state of the art discloses a number of methods for synthesizing and purifying the AI13 polyhydroxyoxoalummum cation (for example Fu G, et al, "Aging Processes of Alumina Sol-

27

Gels; Characterization of New Aluminum Polycations by Al NMR Spectroscopy" Chem.

Mater. 1991, 3(4), pages 602 to 610).

[0012] It is known that the AI13 polyhydroxyoxoalummum cation may be converted to obtain the AI30 polyhydroxyoxoalummum cation by heating a solution of the AI13

polyhydroxyoxoalummum cation (Roswell J et al, "Speciation and Thermal Transformation in

18+

Alumina Sols; Structures of the Polyhydroxyoxoalummum Cluster [Al₃₀ Og (OH)₅₆ (Η₂0)₂6] and its δ-Keggin Moiete", J. Am. Chem. Soc. 2000, 122, pages 3777 to 3778; Chen Z et al, "Effect of thermal treatment on the formation and transformation of Keggin AI13 and AI30 species in hydrolytic polymeric aluminum solutions", Colloids and Surfaces A: Physiochem. Eng.

Aspects, 292 (2007) pages 110 to 118; and Allouche L et al, "Conversion of AI13 Keggin ε into AI30: a reaction controlled by aluminum monomers", Inorganic Chemistry Communications, 6 (2003) pages 1167-1170).

[0013] Heating an AI13 solution is the only synthetic pathway to achieving AI30 which has been described in the literature. As well as the references identified above, WO-A-2006/103092 and Shafran KL et al, "The static anion exchange method for generation of high purity aluminum polyoxocations and monodisperse aluminum hydroxide nano-particles", J. Mater. Chem., 2005, 15, pages 3415 to 3423, disclose the use of an ion-exchange process to synthesize AI13 to achieve greater than 90% purity, and disclose heating the thus-formed AI13 solution to form AI30.

[0014] Partial neutralization of Al salts have been shown to yield trace quantities of the polyhydroxyoxoalummum cation detectable at 76 ppm by 27 Al NMR. There is a need in the art for a high-yield synthetic route to the polyhydroxyoxoalummum cation detectable at 76 ppm by Al NMR. The small quantities obtained, lack of purity, and lack of method of making has prevented science from isolating this polycation in sufficient quantity and purity so that its structure could be determined.

[0015] There is a need in the art for aluminum antiperspirant actives which have high antiperspirant efficacy.

[0016] There is also a need in the art for aluminum antiperspirant actives which have high stability.

[0017] There is also a need in the art for aluminum antiperspirant actives which have the combination of high antiperspirant efficacy and high stability.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a 27 Al NMR spectrograph of material 1 from the examples before heating.

[0019] Figure 2 is a 27 Al NMR spectrograph of material 1 from the examples after heating.

[0020] Figure 3 is a 27 Al NMR spectrograph of material 2 from the examples before heating.

[0021] Figure 4 is a 27 Al NMR spectrograph of material 2 from the examples after heating.

BRIEF SUMMARY OF THE INVENTION

[0022] The present invention is based on modifying the composition from the inventors' earlier work, which was filed as PCT/US2010/55030 on 2 November 2011. It has been discovered that the AI30 in antiperspirant salt can be converted to a species of polyhydroxyoxoaluminum cation

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detectable at 76 ppm by Al NMR. This species also will elute at Peak 4 on a SEC

chromatogram.

[0023] The previous material can be aged for a sufficient time at sufficient temperature to convert the Al₃₀. In one embodiment, the material can be aged at about 100°C for a sufficient period of time, such as about 10 days or greater, or about 30 days or greater. In another embodiment, the material can aged by supercritical heating in an isochoric reaction vessel or under hydrothermal reaction at sufficient temperature and time, such as at 100°C for 5 days. In another embodiment, the material can be aged at ambient conditions (such as 15°C to 60°C) for a period of time of several months, such as at least 6 months, to more than one year.

[0024] The present invention accordingly provides antiperspirant active composition comprising an aluminum salt, the aluminum salt (i) having an aluminum to chloride molar ratio of 0.3: 1 to

3: 1; and (ii) having a species of polyhydroxyoxoaluminum cation detectable at 76 ppm by 27 Al NMR that is present in a relative abundance on a Al NMR spectrograph that is greater than any other polyhydroxyoxoaluminum cation detectable by 27 Al NMR.

[0025] In other embodiments, the species of polyhydroxyoxoaluminum cation detectable at 76 ppm by 27 Al NMR is present in an amount that is a majority of a total amount of all species of

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polyhydroxyoxoaluminum cations detectable by Al NMR. In other embodiments, the species of polyhydroxyoxoaluminum cation detectable at 76 ppm by 27 Al NMR is present in an amount that is at least 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 96, 97, 98, 99, 99.5, 99.9, 99.99, or 99.999% of a total amount of all species of polyhydroxyoxoaluminum cations detectable by 27 Al NMR.

[0026] Optionally, the aluminum salt exhibits a SEC chromatogram having a SEC Peak 4 area of at least 90% of a total area of Peaks 1, 2, 3, 4 and 5 in the SEC chromatogram.

[0027] In this specification, the SEC chromatogram is measured using an aqueous solution of the aluminum salt.

[0028] In some embodiments, the 27 Al NMR spectrum has a species distribution including at most 5% 27

Ali₃ polyhydroxyoxoaluminum cation in the species detectable by A1NMR within the aluminum salt. In some embodiments, the 27 Al NMR spectrum has a species distribution including no 27

AI13 polyhydroxyoxoaluminum cation in the species detectable by A1NMR within the aluminum salt. In some embodiments, the 27 Al NMR spectrum has a species distribution including at most 5% Al_m, Al_m comprising an aluminum-and chloride-containing monomer, in

27

the species detectable by A1NMR within the aluminum salt.

[0029] In some embodiments, the aluminum salt has an OH to Al ratio of at most 2.6: 1, and in other embodiments 2: 1 to 2.6: 1 , optionally an OH to Al ratio of 2: 1 to 2.5 : 1 , or 2.3 : 1 to 2.5 : 1.

[0030] The antiperspirant active composition may optionally further comprise a buffer, wherein a molar ratio of buffer to aluminum is at least 0.1 :1. In other embodiments, the molar ratio is 0.1 : 1 to 3 : 1. The buffer may be at least one buffer chosen from an amino acid, betaine, and quat. Optionally, the buffer is an amino acid and a molar ratio of amino acid to aluminum is at least 0.1 :1. In some embodiments, the amino acid is glycine.

[0031] In some embodiments, the composition has a SEC Peak 4 area of at least 95% of a total area of Peaks 1, 2, 3, 4 and 5 in the SEC chromatogram. In some embodiments, the composition has a SEC Peak 3 area of less than 5% of a total area of Peaks 1, 2, 3, 4 and 5 in the SEC chromatogram, and most preferably has no SEC Peak 3 area in the SEC chromatogram. [0032] In some embodiments, the composition has a SEC Peak 5 area of less than 5% of a total area of Peaks 1, 2, 3, 4 and 5 in the SEC chromatogram, and most preferably has no SEC Peak 5 area in the SEC chromatogram.

[0033] In some embodiments, the antiperspirant active composition has a SEC Peak 4 area of 95 to 100%, no SEC Peak 3 area, and a SEC Peak 5 area of from 0 to 5% of a total area of Peaks 1, 2, 3, 4 and 5 in the SEC chromatogram.

[0034] The antiperspirant active composition may further comprise zirconium, and optionally a molar ratio of aluminum to zirconium is 5 : 1 to 10:1.

[0035] A method of making an antiperspirant active composition comprising:

I) heating an aqueous solution containing i) a first aluminum salt containing an AI30

polyhydroxyoxoaluminum cation and having an aluminum to chloride molar ratio of 0.3: 1 to 3: 1, ii) an inorganic salt, and iii) a buffer, wherein the buffer is at least one of an amino acid, betaine, and quat and a molar ratio of buffer to aluminum is at least 0.1 : 1, wherein the heating is one of

a) at a temperature of 100°C to 250°C in an isochoric reactor or under hydrothermal reaction for a time sufficient to form a species of polyhydroxyoxoaluminum cation detectable at 76 ppm by 27 Al NMR; or

b) at 100°C at reflux for about 10 days or greater, optionally about 30 days or greater to form a fourth aluminum salt.

[0036] The present invention also provides a method of making an antiperspirant active composition comprising:

I) heating an aqueous solution containing a first aluminum salt having an aluminum to chloride molar ratio of 0.3 : 1 to 3 : 1 and a buffer, wherein the buffer is at least one of an amino acid, betaine, and quat and a molar ratio of buffer to aluminum is at least 0.1 : 1 , at a temperature of 50°C to 100°C for a period of time of 1 hour to 6 hours to obtain a first aluminum salt solution;

II) adding to the first aluminum salt solution an aqueous solution of an inorganic base to obtain a second pH adjusted aluminum salt solution having an OH:Al molar ratio of at most 2.6: 1 , or optionally 2: 1 to 2.6: 1 , and a pH of 2 to 5; III) heating the second pH adjusted aluminum salt solution at a temperature of 50°C to 100°C for a period of time of at least 6 hours to obtain a third aluminum salt solution containing an AI30 polyhydroxyoxoalummum cation;

IV) heating the third aluminum salt solution at one of

a) at a temperature of 100°C to 250°C in an isochoric reactor or under

hydrothermal reaction for a time sufficient to form a species of polyhydroxyoxoalummum cation detectable at 76 ppm by 27 Al NMR; or b) at 100°C at reflux for about 10 days or greater, optionally about 30 days or greater;

to form a fourth aluminum salt; and

V) optionally adding an aqueous solution containing a zirconium compound to the second pH adjusted aluminum salt solution to thereby obtain a second pH adjusted aluminum-zirconium salt solution having a molar ratio of aluminum to zirconium of 5: l to 10: 1.

[0037] The present invention also provides a method of making a polyhydroxyoxoalummum cation detectable at 76 ppm by 27 Al NMR comprising storing an aqueous solution containing i) the aluminum salt containing an AI30 polyhydroxyoxoalummum cation and having an aluminum to chloride molar ratio of 0.3 : 1 to 3 : 1 , ii) an inorganic salt, and iii) a buffer, wherein the buffer is at least one of an amino acid, betaine, and quat, and a molar ratio of buffer to aluminum is at least 0.1 :1 at a temperature of 15°C to 60°C for a period of time until the

polyhydroxyoxoalummum cation detectable at 76 ppm by 27 Al NMR that is present in a relative abundance on a 27 Al NMR spectrograph that is greater than any other polyhydroxyoxoalummum cation detectable by ²⁷ Al NMR.

[0038] In some embodiments, the buffer is glycine. In some embodiments, the inorganic salt is at least one chloride salt chosen from calcium chloride, magnesium chloride, strontium chloride, barium chloride, stannous chloride, and yttrium chloride. In some embodiments, the inorganic base includes at least one member chosen from calcium hydroxide, magnesium hydroxide, strontium hydroxide, barium hydroxide, stannous hydroxide, yttrium hydroxide, calcium oxide, magnesium oxide, strontium oxide, barium oxide, stannous oxide, yttrium oxide, calcium carbonate, magnesium carbonate, strontium carbonate, barium carbonate, stannous carbonate, and yttrium carbonate. Typically, the inorganic base is calcium hydroxide. In some embodiments, the aluminum salt solution has an OH to Al molar ratio of 2.0: 1 to 2.5 : 1 or 2.1 : 1 to 2.5: 1.

[0039] In some embodiments, the first aluminum salt is an aluminum chloride compound chosen from aluminum trichloride, aluminum chlorohexahydrate, aluminum dichlorohydrate, and aluminum monochlorohydrate. Optionally, the composition further comprises zirconium. The zirconium compound may be ZrOCl₂-8H₂0 or Oxo-Hexameric Zirconium-Octaamino Acid.

[0040] In some embodiments, the fourth aluminum salt has a SEC Peak 4 area of at least 95% of a total area of Peaks 1, 2, 3, 4 and 5 in the SEC chromatogram. In some embodiments, the fourth aluminum salt has a SEC Peak 3 area of less than 5% of a total area of Peaks 1, 2, 3, 4 and 5 in the SEC chromatogram, and preferably the fourth aluminum salt has no SEC Peak 3 area in the SEC chromatogram. In some embodiments, the fourth aluminum salt has a SEC Peak 5 area of less than 5% of a total area of Peaks 1, 2, 3, 4 and 5 in the SEC chromatogram.

[0041] In some embodiments, in step III) the period of time is at least 12 hours, or in some embodiments at least 24 hours.

[0042] The present invention further provides the use of a heating step to convert AI30

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polyhydroxyoxoalummum cations in the species detectable by Al NMR within an aqueous aluminum salt solution into a species of polyhydroxyoxoalummum cation detectable at 76 ppm by 27 Al NMR, the aqueous aluminum salt solution i) having an aluminum to chloride molar ratio of 0.3:1 to 3: 1; ii ) an inorganic salt, and iii) a buffer, wherein the buffer is at least one of an amino acid, betaine, and quat, and a molar ratio of buffer to aluminum is at least 0.1 : 1 ; an OH: Al molar ratio of at most 2.6: 1, or optionally, 2: 1 to 2.6: 1; and the heating step is one of:

a) at a temperature of 100°C to 250°C in an isochoric reactor or under hydrothermal

reaction for a time sufficient to form a species of polyhydroxyoxoalummum cation detectable at 76 ppm by ²⁷ Al NMR; or

b) at 100°C at reflux for about 10 days or greater, optionally about 30 days or greater.

[0043] In some embodiments, the heating step converts all the AI13 polyhydroxyoxoalummum cation species present in the aqueous aluminum salt solution into the AI30

polyhydroxyoxoalummum cation species. In some embodiments, the heating step reduces a SEC Peak 5 area in the SEC chromatogram. Optionally, the period of time is at least 12 hours or, in other embodiments, at least 24 hours. In some embodiments, the buffer is glycine. [0044] In some embodiments, the OH:Al molar ratio has been achieved by adding to the aqueous aluminum salt solution an inorganic base including at least one member chosen from calcium hydroxide, magnesium hydroxide, strontium hydroxide, barium hydroxide, stannous hydroxide, yttrium hydroxide, calcium oxide, magnesium oxide, strontium oxide, barium oxide, stannous oxide, yttrium oxide, calcium carbonate, magnesium carbonate, strontium carbonate, barium carbonate, stannous carbonate, and yttrium carbonate. Typically, the inorganic base is calcium hydroxide. Optionally, the OH to Al molar ratio is 2.0: 1 to 2.5 : 1 or 2.1 : 1 to 2.5 : 1.

[0045] In some embodiments, the aluminum salt is an aluminum chloride compound chosen from aluminum trichloride, acidified aluminum chlorohexahydrate, aluminum dichlorohydrate, and aluminum monochlorohydrate.

[0046] In some embodiments, the heating increases the AI30 polyhydroxyoxoaluminum cation

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species in the A1NMR spectrum from at least 90% to at least 95% of the species detectable by ²⁷A1NMR within the aluminum salt.

[0047] In some embodiments, after the heating step the aluminum salt has a SEC Peak 4 area of at least 95% of a total area of Peaks 1, 2, 3, 4 and 5 in the SEC chromatogram. In some embodiments, after the heating step the aluminum salt has a SEC Peak 3 area of less than 5% of a total area of Peaks 1, 2, 3, 4 and 5 in the SEC chromatogram, and preferably has no SEC Peak 3 area in the SEC chromatogram. In some embodiments, after the heating step the aluminum salt has a SEC Peak 5 area of less than 5% of a total area of Peaks 1, 2, 3, 4 and 5 in the SEC chromatogram.

[0048] The present invention further provides an antiperspirant active composition including an aluminum salt produced by the method of the invention or the use of the invention.

DETAILED DESCRIPTION OF THE INVENTION

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[0049] In this specification, the use of Al NMR data is not quantitative but considers only NMR- visible Al species and in particular resonances at 0 ppm, 62.5 ppm, 70 ppm, and 76 ppm.

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Octahedrally coordinated nuclei are detected via Al NMR. The Al monomer resonance at 0 ppm is octahedrally coordinated. Octahedral bands in AI13 and AI30 are broad and overlapping, so they're not useful when identifying Al species. The breadth of octahedral bands in AI13 & AI30 is due to structural and environmental variation. Because the Al nuclei in monomeric Al exist structurally in one form, the signal is narrow, and easily identified. Tetrahedrally coordinated nuclei in AI13 and AI30 also feature minimal variation, which leads to narrow, identifiable NMR signals. Al NMR data do not indicate the amount of undetected Al embodied in NMR-invisible species.

[0050] When calculating the relative amounts of Al embodied in compositions containing

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Al NMR visible species that have known structures, such as Ali₃ and Al ₀

polyhydroxyoxoalummum cations, the tetrahedral resonance peak of the aluminum is integrated and multiplied by a scaling factor to account for other octahedrally coordinated Al present in the structure. In the Ali₃ polyhydroxyoxoalummum cation, there is one tetrahedral resonance peak in the structure. In the Al₃o polyhydroxyoxoalummum cation, there are two tetrahedral resonance peaks in the structure. To convert, the resonance from the Ali₃

polyhydroxyoxoalummum cation is multiplied by 13, whereas the resonance from the Al₃₀ polyhydroxyoxoalummum cation is multiplied by 15. When the structure of the 76 ppm material is identified, a scaling factor can be determined.

[0051] For now, the amounts of each species of polyhydroxyoxoalummum cation in a composition will be characterized by the relative abundance of tetrahedral aluminum resonance peaks on a 27 Al NMR spectrograph. This means that the area of the tetrahedral aluminum resonance peak for a polyhydroxyoxoalummum cation is compared to the area of the tetrahedral aluminum resonance peaks for other polyhydroxyoxoalummum cations. The 27 Al NMR spectrograph should be collected at sufficient enough field strength so that all relevant signals

27

can be integrated. One procedure for operating a Al NMR is described in the examples below. In the current state of the art, the resonance frequency is at least 104.2 Mhz to provide a sufficient field strength.

[0052] The present invention is directed to antiperspirant active composition comprising an aluminum salt, the aluminum salt (i) having an aluminum to chloride molar ratio of 0.3 : 1 to 3 : 1 ; and (ii) having a species of polyhydroxyoxoalummum cation detectable at 76 ppm by 27 Al NMR that is present in a relative abundance on a 27 Al NMR spectrograph that is greater than any other polyhydroxyoxoalummum cation detectable by 27 Al NMR.

[0053] In certain embodiments, the species of polyhydroxyoxoalummum cation detectable at 76 ppm by ²⁷ Al NMR is present in an amount that is at least 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 96, 97, 98, 99, 99.5, 99.9, 99.99, or 99.999% of a total amount of all species of

polyhydroxyoxoalummum cation detectable by 27 Al NMR. In other embodiments, the species of polyhydroxyoxoalummum cation detectable at 76 ppm by 27 Al NMR is present in an amount that is a majority of a total amount of all species of polyhydroxyoxoalummum cations detectable by ²⁷ Al NMR.

[0054] The species of polyhydroxyoxoalummum cation detectable at 76 ppm by 27 Al NMR can be made by heating an aqueous solution containing i) a first aluminum salt containing an AI30 polyhydroxyoxoalummum cation and having an aluminum to chloride molar ratio of 0.3: 1 to 3: 1, ii) an inorganic salt, and iii) a buffer, wherein the buffer is at least one of an amino acid, betaine, and quat, and a molar ratio of buffer to aluminum is at least 0.1 : 1, wherein the heating is one of a) at a temperature of 100°C to 250°C in an isochoric reactor or under hydrothermal

[0055] The reaction in the isochoric reactor is conducted at 100°C to 250°C. As the temperature increases, the time need to convert AI30 polyhydroxyoxoalummum cation to the

polyhydroxyoxoalummum cation detectable at 76 ppm by 27 Al NMR decreases. Below are some examples of temperature and time:

i) at 100°C for about 5 days,

ii) at 120°C for about 12 hours, or

iii) at 150°C for about 20 minutes.

[0056] The inorganic salt and buffer help to stabilize the species of polyhydroxyoxoalummum

27

cation detectable at 76 ppm by Al NMR. In certain embodiments, the inorganic salt is at least one chloride salt chosen from calcium chloride, strontium chloride, barium chloride, magnesium chloride, stannous chloride, and yttrium chloride. In one embodiment, the salt is calcium chloride. In certain embodiments, the buffer is glycine. In certain embodiments, the inorganic salt is calcium chloride and the buffer is glycine.

[0057] The present invention can provide an antiperspirant active composition having a high SEC peak 4 in aqueous solution. The composition is obtained by a stepwise procedure to neutralize aluminum chloride in a solution (optionally buffered) using inorganic bases. In some embodiments, the antiperspirant active compositions obtained by this stepwise procedure include aluminum salts having an aluminum to chloride molar ratio of 0.3: 1 to 3: 1, optionally, the aluminum salt exhibits a SEC chromatogram having a SEC Peak 4 area of at least 90% of a total area of Peaks 1, 2, 3, 4 and 5 in the SEC chromatogram in aqueous solution. The composition may optionally include zirconium.

[0058] The description below describes methods of obtaining an Al₃₀ polyhydroxyoxoaluminum cation containing composition.

[0059] The Al₃₀ containing compositions may be made in a variety of ways involving a stepwise procedure to neutralize aluminum chloride in solution (optionally buffered) using inorganic basic salts. The procedure generally includes the step of heating an aqueous solution containing an aluminum chloride compound (optionally with a buffer agent) at a temperature of 50°C to 100°C, optionally 50°C to 95°C, for a period of time of 1 hour to 6 hours. The heating may be under stirring, such as vigorous stirring, or under reflux. In one such embodiment, an aqueous solution containing an aluminum chloride compound and a buffer agent is heated at a temperature of 75°C to 95°C to reflux for a period of time of 2 hours to 4 hours. In one embodiment, the temperature is 95°C under vigorous stirring for a period of time of 2.5 hours.

[0060] To adjust the pH of the aluminum salt solution, an aqueous solution of an inorganic base is added to the heated solution to thereby obtain a pH adjusted aluminum salt solution having a hydroxide to aluminum molar ratio of 1 : 1 to 4 : 1 , and a pH of 2 to 5. In one such embodiment, the hydroxide to aluminum molar ratio of 2: 1 to 3 : 1. In another such embodiment, the hydroxide to aluminum molar ratio is 2.1 : 1 to 2.6: 1.

[0061] In one embodiment, the inorganic base can be at least one base chosen from metal hydroxides, calcium hydroxide, magnesium hydroxide, strontium hydroxide, barium hydroxide, stannous hydroxide, yttrium hydroxide, calcium oxide, magnesium oxide, strontium oxide, barium oxide, stannous oxide, yttrium oxide, calcium carbonate, magnesium carbonate, strontium carbonate, barium carbonate, stannous carbonate, and yttrium carbonate.

[0062] Optionally, a buffer can be included. Buffers that can be used can be chosen from amino acids, such as glycine, and betaine, such as betaine monohydrate, or quats. The buffer to aluminum molar ratio in certain embodiments can be at least 0.1 : 1 , or 0.1 : 1 to 3 : 1. In another embodiment, the buffer to aluminum molar ratio is 0.1 : 1 to 2: 1.

[0063] In one embodiment, the inorganic base is calcium hydroxide. In one such embodiment, the addition of calcium hydroxide provides an aqueous solution having a Ca(OH)₂: glycine molar ratio of at least 0.1 : 1. [0064] When a buffer is absent, significant Peak 3 species in the SEC chromatogram begin to form when the total Al concentration is above 0.2M. When a buffer is present, the total Al concentration can reach up to 2.5M while maintaining a predominant Peak 4 in the SEC chromatogram. In one embodiment, an aqueous aluminum chloride salt solution is buffered with glycine and held at 50°C to 95°C under vigorous stirring for a period time of 1 to 6 hours. To the heated solution, an aqueous solution of an inorganic base is added dropwise over a period of time of 1 to 3 hours while maintaining the aluminum-glycine solution at 50°C to 95°C under vigorous stirring. In one such embodiment, the solution has a glycine to aluminum molar ratio of 1.5. In another such embodiment, the solution has a glycine to aluminum molar ratio of 0.5.

[0065] In some embodiments, a zirconium salt may also be added to the pH adjusted aluminum salt solution. In one other such embodiment, the molar ratio of Al : Zr is 5 : 1 to 10 : 1. The zirconium salt may be simple Zr salts: ΖΓ0Ο₂·8Η₂0 or Oxo-Hexameric Zirconium-Octaamino Acid. In one such embodiment, the molar ratio of Al: Zr is 8. In another such embodiment, the molar ratio of Al: Zr is 7. In one other such embodiment, the molar ratio of Al: Zr is 9.

[0066] For the above methods, the aluminum chloride salt and inorganic base may be obtained from a variety of sources. In one embodiment, the aluminum chloride salt includes aluminum trichloride, acidified aluminum chlorohexahydrate, aluminum dichlorohydrate, and aluminum monochlorohydrate. In one such embodiment, the aluminum chloride salt is aluminum chlorohexahydrate .

[0067] The present invention provides for aluminum antiperspirant active compositions and/or aluminum-zirconium antiperspirant active compositions having high levels of low molecular weight Al and Zr species. The high levels of low molecular weight Al and Zr species is reflected in a SEC trace that has an intense Peak 4 and low Peaks 1, 2, 3 and 5. The polymerization of the antiperspirant actives in aqueous solutions and the correspondent gelation process were followed by monitoring the molecular weight profile of the polyoxohalides in time by SEC. The relative retention time ("Kd") for each of these peaks varies depending on the experimental conditions, but the peaks remain relative to each other. The SEC data for the examples was obtained using an SEC chromatogram using the following parameters: Waters® 600 analytical pump and controller, Rheodyne® 77251 injector, Protein-Pak® 125 (Waters) column, Waters 2414

Refractive Index Detector. 5.56mM nitric acid mobile phase, 0.50ml/min flow rate, 2.0 microliter injection volume. Data was analyzed using Waters® Empower software (Waters Corporation, Milford, Mass.). The concentration of the antiperspirant in aqueous solution does not affect the retention time in the machine.

[0068] The design of modern antiperspirant (AP) salts aims at actives with high levels of low molecular weight Al and Zr species, which is reflected in a SEC trace that has intense Peak 4 and low Peaks 1 , 2, and 3, and optionally low Peak 5. Throughout the present study, the levels of the species corresponding to these peaks are estimated based on the following ratios (or

percentages):

Pi

fpi = ττ-. i = 1 , 2, 3, 4, 5; j = 2, 3, 4, 5

where fpi is the fraction of peak i, and Pi or Pj are the intensity of peaks Pi or Pj, respectively. The amount of low molecular weight Al species will be correlated with the fraction, fp₄, or percentage, fp₄ xlOO, of SEC-Peak 4. In brief, a preferred antiperspirant salt would have a very low fpi , fp2, fp3, and/or f_P5, and a high f_P4.

[0069] In certain embodiments, the ratio of Peak 4 to Peak 3 is at least 8, 9, 10, 1 1 , 12, 13, 14, 15, 16, 17, 18, 19, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, or any number up to infinity. Preferably, Peak 3 is so low as to be undetectable.

[0070] In one embodiment, an aluminum salt and/or aluminum-zirconium salt, in aqueous solution, exhibit a SEC profile wherein the SEC Peak 4 to Peak 3 intensity ratio is even as high as infinity, because the Peak 3 is undetectable. In some embodiments, the percentage of SEC Peak 4 of a total area of Peaks 1 , 2, 3, 4 and 5 in the SEC chromatogram is: at least at least 90%; at least 95%, or 95 to 100%. In another such embodiment, the SEC Peak 4 area is 100%.

[0071] In another embodiment, the aluminum salt and/or the aluminum-zirconium salt, in aqueous solution, exhibits a SEC profile which exhibits low percentage of SEC Peak 3. In such embodiments, the composition has the percentage of SEC Peak 3 area of a total area of Peaks 1 , 2, 3, 4 and 5 in the SEC chromatogram is: less than 5 %; less than 2 %; less than 1 %; less than 0.9 %; less than 0.8 %; less than 0.7 %; less than 0.6 %; of less than 0.5 %; less than 0.4 %; less than 0.3 %; less than 0.2 %; or less than 0.1 %. In another such embodiment, the composition has no SEC Peak 3 area.

[0072] In another embodiment, the aluminum salt and/or the aluminum-zirconium salt, in aqueous solution, exhibits a SEC profile which exhibits low percentages of SEC Peak 5. In such embodiments, the percentage of SEC Peak 5 area of a total area of Peaks 1, 2, 3, 4 and 5 in the SEC chromatogram is: less than 5 %; or less than 1 %. In another such embodiment, the composition has no SEC Peak 5 area.

[0073] In other embodiments, the aluminum salt and/or the aluminum-zirconium salt, in aqueous solution, exhibits a SEC profile which exhibits a low percentage of SEC Peak 1 and a low percentage of SEC Peak 2. In such embodiments, the percentage of SEC Peak 1 area of a total area of Peaks 1, 2, 3, 4 and 5 in the SEC chromatogram is less than 5 %; less than 2 %; or less than 1 %, or the salt has no SEC Peak 1 area. In other embodiments, the percentage of SEC Peak 2 area of a total area of Peaks 1, 2, 3, 4 and 5 in the SEC chromatogram is less than 5 %; less than 2 % or less than 1 %; or the salt has no SEC Peak 2 area. Preferably, the salt has no Peak 1 area and no Peak 2 area. More preferably, the salt has no Peak 1 area, no Peak 2 area and no Peak 3 area. Yet more preferably, the salt has no Peak 1 area, no Peak 2 area, no Peak 3 area and no Peak 5 area.

[0074] The aluminum antiperspirant active compositions and/or aluminum-zirconium

antiperspirant active compositions may be used in a variety of antiperspirant products. If the product is used as a solid powder, the size of the particles of antiperspirant active of the invention can be any desired size, and may include conventional sizes such as in the range of 2 to 100 microns, with selected grades having an average particle size of 30-40 microns; finer sized grades having an average particle size distribution of 2-10 microns with an average size of 7 microns as made by a suitable dry-grinding method; and micronized grades having an average particle size of less than or equal to 2 microns, or less than or equal to 1.5 microns.

[0075] The compositions of this invention may be used to formulate antiperspirants having improved efficacy. Such antiperspirants include solids such as sticks and creams (creams sometimes being included in the term "soft solid"), gels, liquids (such as are suitable for roll-on products), and aerosols. The forms of these products may be suspensions or emulsions. These antiperspirant actives can be used as the antiperspirant active in any antiperspirant composition. Examples of formulations can be found in WO2009/076591.

[0076] The present invention is exemplified by the following non-limiting Examples.

EXAMPLES [0077] Two materials prepared in accordance with PCT/US2010/55030 are provided. The materials are aqueous systems that contain the glycine buffer and the calcium chloride byproduct of the manufacturing process.

27

[0078] The raw integration values for Al NMR spectroscopy peaks for these materials are listed below in Table 1, and Table 2 shows the relative abundance. The materials are analyzed by taking a 1 M solution and diluting in a 1 :4 ratio using D₂0. The final Al concentration for all

27

samples is 0.25M. The samples are analyzed at a Al resonance frequency of 104.2 MHz at 90°C. A coaxial insert containing NaA10₂ is included to provide a reference resonance peak at 80ppm. The instrument collects 1500 transients, with a pulse width of 6.4μ8 and a delay time of 2 seconds. The data for the relevant peaks are shown in the tables below. The full spectrographs can be seen in Figures 1 to 4.

[0079] Materials 1 is held at reflux for 30 days at 100°C. Material 2 is subjected to 100°C for 5 days in an isochoric reaction vessel. For comparative purposes, the following discussion relates only with the relative integrations instead of raw data.

[0080] For Material 1, the AI30 signal (encompassing 96.10% of the total visible tetrahedral Al) is converted to a signal at 76 ppm (97.76% Td Al). Also, the amount of AI13 is reduced from 3.90% to 2.24%.

[0081] For Material 2, the AI30 signal at 70 ppm (encompassing 98.44% of the total visible tetrahedral Al) is converted to a signal at 76 ppm (99.37% Td Al). Also, the amount of AI13 is reduced from 1.56% to 0.63%.

TABLE 1

Table 2

[0082] As used throughout, ranges are used as shorthand for describing each and every value that is within the range. Any value within the range can be selected as the terminus of the range. In addition, all references cited herein are hereby incorporated by referenced in their entireties. In the event of a conflict in a definition in the present disclosure and that of a cited reference, the present disclosure controls.

[0083] Unless otherwise specified, all percentages and amounts expressed herein and elsewhere in the specification should be understood to refer to percentages by weight. The amounts given are based on the active weight of the material.

Claims

WHAT IS CLAIMED IS:

1. An antiperspirant active composition comprising an aluminum salt, the aluminum salt (i) having an aluminum to chloride molar ratio of 0.3 : 1 to 3 : 1 ; and (ii) having a species of polyhydroxyoxoaluminum cation detectable at 76 ppm by 27 Al NMR that is present in a relative abundance on a 27 Al NMR spectrograph that is greater than any other polyhydroxyoxoaluminum cation detectable by 27 Al NMR.

2. The antiperspirant active composition of claim 1, wherein the species of

polyhydroxyoxoaluminum cation detectable at 76 ppm by 27 Al NMR is present in an amount that is at least 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 96, 97, 98, 99, 99.5, 99.9, 99.99, or 99.999% of a total amount of all species of polyhydroxyoxoaluminum cation detectable by ²⁷ Al NMR.

3. The antiperspirant active composition of any foregoing claim, wherein the species of polyhydroxyoxoaluminum cation detectable at 76 ppm by 27 Al NMR is present in an amount that is a majority of a total amount of all species of polyhydroxyoxoaluminum cations detectable by ²⁷ Al NMR.

4. The antiperspirant active composition of any foregoing claim, wherein the aluminum salt exhibits a SEC chromatogram having a SEC Peak 4 area of at least 90% of a total area of Peaks 1, 2, 3, 4 and 5 in the SEC chromatogram

5. The antiperspirant active composition of any foregoing claim, wherein the 27 Al NMR spectrum has a species distribution including at most 5% AI13 polyhydroxyoxoaluminum cation in the species detectable by 27 Al NMR within the aluminum salt.

6. The antiperspirant active composition of any foregoing claim, wherein the 27 Al NMR spectrum has a species distribution including no AI13 polyhydroxyoxoaluminum cation in

27

the species detectable by A1NMR within the aluminum salt.

7. The antiperspirant active composition of any foregoing claim, wherein the aluminum salt has an OH to Al ratio of at most 2.6: 1, or 2: 1 to 2.6: 1.

8. The antiperspirant active composition of any foregoing claim, wherein the aluminum salt has an OH to Al ratio of 2: 1 to 2.5 : 1 , or optionally 2.3 : 1 to 2.5 : 1.

9. The antiperspirant active composition of any foregoing claim, further comprising a buffer, wherein a molar ratio of buffer to aluminum is at least 0.1 : 1 , or optionally 0.1 : 1 to 3: 1.

10. The antiperspirant active composition of claim 10, wherein the buffer is at least one buffer chosen from an amino acid, betaine, and quat.

11. The antiperspirant active composition of claim 11 , wherein the buffer is an amino acid and a molar ratio of amino acid to aluminum is at least 0.1, optionally the amino acid is glycine.

12. The antiperspirant active composition of any foregoing claim, wherein the composition has a SEC Peak 4 area of at least 95% of a total area of Peaks 1, 2, 3, 4 and 5 in the SEC chromatogram.

13. The antiperspirant active composition of any foregoing claim, wherein the composition has a SEC Peak 3 area of less than 5% of a total area of Peaks 1, 2, 3, 4 and 5 in the SEC chromatogram, optionally no SEC Peak 3 area in the SEC chromatogram.

14. The antiperspirant active composition of any foregoing claim, wherein the composition has a SEC Peak 5 area of less than 5% of a total area of Peaks 1, 2, 3, 4 and 5 in the SEC chromatogram, optionally no SEC Peak 5 area in the SEC chromatogram.

15. The antiperspirant active composition of any foregoing claim, wherein the composition has a SEC Peak 4 area of 95 to 100%, no SEC Peak 3 area, and a SEC Peak 5 area of from 0 to 5% of a total area of Peaks 1, 2, 3, 4 and 5 in the SEC chromatogram.

16. The antiperspirant active composition of any foregoing claim, wherein the composition further comprises zirconium.

17. The antiperspirant active composition of claim 17, wherein a molar ratio of aluminum to zirconium is 5 : 1 to 10: 1.

18. A method of making an antiperspirant active composition comprising:

I) heating an aqueous solution containing i) a first aluminum salt containing an AI30 polyhydroxyoxoaluminum cation and having an aluminum to chloride molar ratio of 0.3:1 to 3: 1, ii) an inorganic salt, and iii) a buffer, wherein the buffer is at least one of an amino acid, betaine, and quat, and a molar ratio of buffer to aluminum is at least 0.1 : 1, wherein the heating is one of a) at a temperature of 100°C to 250°C in an isochoric reactor or under hydrothermal reaction for a time sufficient to form a species of polyhydroxyoxoaluminum cation detectable at 76 ppm by 27 Al NMR; or b) at 100°C at reflux for about 10 days or greater, optionally for about 30 days or greater,

to form a fourth aluminum salt.

A method of making an antiperspirant active composition comprising:

I) heating an aqueous solution containing a first aluminum salt having an aluminum to chloride molar ratio of 0.3 : 1 to 3 : 1 and a buffer, wherein the buffer is at least one of an amino acid, betaine, and quat, and a molar ratio of buffer to aluminum is at least 0.1 : 1 , at a temperature of 50°C to 100°C for a period of time of 1 hour to 6 hours to obtain a first aluminum salt solution;

II) adding to the first aluminum salt solution an aqueous solution of an inorganic base to obtain a second pH adjusted aluminum salt solution having an OH:Al molar ratio of at most 2.6: 1 , or optionally 2: 1 to 2.6: 1 , and a pH of 2 to 5;

III) heating the second pH adjusted aluminum salt solution at a temperature of 50°C to 100°C for a period of time of at least 6 hours to obtain a third aluminum salt solution containing an AI30 polyhydroxyoxoaluminum cation;

IV) heating the third aluminum salt solution at one of

a) at a temperature of 100°C to 250°C in an isochoric reactor for a time sufficient to form a species of polyhydroxyoxoaluminum cation detectable at 76 ppm by ²⁷ Al NMR; or

b) at 100°C at reflux for about 30 days or greater;

to form a fourth aluminum salt; and

The method of claim 18, wherein the inorganic salt is at least one chloride salt chosen from calcium chloride, strontium chloride, barium chloride, and yttrium chloride.

The method of claim 18, wherein the buffer is glycine.

22. The method of claim 18, wherein the inorganic salt is calcium chloride and the buffer is glycine.

23. The method of claim 18 or 19, wherein heating in the isochoric reactor or under

hydrothermal reaction is one of

i) at 100°C for about 5 days,

ii) at 120°C for about 12 hours, or

iii) at 150°C for about 20 minutes.

24. The method of any one of claims 18 to 23, wherein the aluminum salt exhibits a SEC chromatogram having a SEC Peak 4 area of at least 90% of a total area of Peaks 1, 2, 3, 4 and 5 in the SEC chromatogram.

25. The method of claim 19 or 24, wherein the buffer is glycine.

26. The method of any one of claims 19 or 23 to 25, wherein the inorganic base includes at least one member chosen from calcium hydroxide, strontium hydroxide, barium hydroxide, calcium oxide, strontium oxide, barium oxide, calcium carbonate, barium carbonate, strontium carbonate, yttrium hydroxide, yttrium oxide, and yttrium carbonate.

27. The method of claim 26, wherein the inorganic base is calcium hydroxide.

28. The method of any one of claims 19 or 23 to 27, wherein the second pH adjusted

aluminum salt solution has an OH to Al molar ratio of 2: 1 to 2.5 : 1 , or optionally 2.3 : 1 to 2.5: 1.

29. The method of any one of claims 19 or 23 to 28, wherein the first aluminum salt is an aluminum chloride compound chosen from aluminum trichloride, aluminum

chlorohexahydrate, and aluminum dichlorohydrate.

30. The method of any one of claims 19 or 23 to 29, wherein the composition further

comprises zirconium and step V) is present in the method.

31. The method of claim 31 , wherein the zirconium compound is ZrOCl₂-8H₂0.

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32. The method of any one of claims 18 to 31 , wherein the Al NMR spectrum has a species distribution including at most 5% AI13 polyhydroxyoxoaluminum cation in the species detectable by 27 Al NMR within the fourth aluminum salt, optionally no AI13

polyhydroxyoxoaluminum cation.

33. The method of any one of claims 18 to 32, wherein the fourth aluminum salt has a SEC Peak 4 area of at least 95% of a total area of Peaks 1, 2, 3, 4 and 5 in the SEC

chromatogram.

34. The method of any one of claims 18 to 33, wherein the fourth aluminum salt has a SEC Peak 3 area of less than 5% of a total area of Peaks 1, 2, 3, 4 and 5 in the SEC

chromatogram, optionally no SEC Peak 3 area in the SEC chromatogram.

35. The method of any one of claims 19 or 23 to 34, wherein the third aluminum salt has a SEC Peak 5 area of less than 5% of a total area of Peaks 1, 2, 3, 4 and 5 in the SEC chromatogram.

36. The method according to any one of claims 19 or 23 to 35, wherein in step III) the period of time is at least 12 hours, or optionally at least 24 hours.

37. A method of making a polyhydroxyoxoaluminum cation detectable at 76 ppm by 27 Al NMR comprising storing an aqueous solution containing i) the aluminum salt containing an AI30 polyhydroxyoxoaluminum cation and having an aluminum to chloride molar ratio of 0.3:1 to 3: 1 , ii) an inorganic salt, and iii) a buffer, wherein the buffer is at least one of an amino acid, betaine, and quat, and a molar ratio of buffer to aluminum is at least 0.1 : 1 at a temperature of 15°C to 60°C for a period of time until the polyhydroxyoxoaluminum cation detectable at 76 ppm by ²⁷ Al NMR that is present in a relative abundance on a ²⁷ Al NMR spectrograph that is greater than any other polyhydroxyoxoaluminum cation detectable by ²⁷ Al NMR.

38. Use of a heating step to convert AI30 polyhydroxyoxoaluminum cations in the species detectable by 27 Al NMR within an aqueous aluminum salt solution into a species of polyhydroxyoxoaluminum cation detectable at 76 ppm by 27 Al NMR, the aqueous aluminum salt solution i) having an aluminum to chloride molar ratio of 0.3 : 1 to 3 : 1 ; ii ) an inorganic salt, and iii) a buffer, wherein the buffer is at least one of an amino acid, betaine, and quat, and a molar ratio of buffer to aluminum is at least 0.1 : 1 ; an OH:Al molar ratio of at most 2.6: 1, or optionally, 2: 1 to 2.6: 1; and the heating step is one of: a) at a temperature of 100°C to 250°C in an isochoric reactor for a time sufficient to form a species of polyhydroxyoxoaluminum cation detectable at 76 ppm by 27 Al NMR; or

b) at 100°C at reflux for about 30 days or greater.

39. The use according to claim 38, wherein the buffer is glycine.

40. The use according to any one of claims 38 to 39, wherein the OH:Al molar ratio has been achieved by adding to the aqueous aluminum salt solution an inorganic base including at least one member chosen from calcium hydroxide, strontium hydroxide, barium hydroxide, calcium oxide, strontium oxide, barium oxide, calcium carbonate, barium carbonate, strontium carbonate, yttrium hydroxide, yttrium oxide, and yttrium carbonate.

41. The use of claim 40, wherein the inorganic base is calcium hydroxide.

42. The use of any one of claims 38 to 41, wherein the OH to Al molar ratio is 2: 1 to 2.5: 1, or optionally 2.3: 1 to 2.5 : 1.

43. The use of any one of claims 38 to 42, wherein the aluminum salt is an aluminum

chloride compound chosen from aluminum trichloride, aluminum chlorohexahydrate, and aluminum dichlorohydrate.

44. An antiperspirant active composition including an aluminum salt produced by the method of any one of claims 18 to 37 or the use of any one of claims 38 to 43.