Europaisches Patentamt (19) European Patent Office Office europeeneen des brevets EP 0 905 115 A1 (12) EUROPEAN PATENT APPLICATION (43) Date of publication: (51) |nt CI * C07C 41/56, C07C 43/303, 31.03.1999 Bulletin 1999/13 C1 1 D 3/50 (21) Application number: 98870194.2 (22) Date of filing: 16.09.1998 (84) Designated Contracting States: (72) Inventors: AT BE CH CY DE DK ES Fl FR GB GR IE IT LI LU • Masami, Ono MC NL PT SE Higashinada-ku, Kobe 658 (JP) Designated Extension States: • Masahiro, Ishida AL LT LV MK RO SI Nagata-ku, Kobe 653 (JP) (30) Priority: 26.09.1997 US 17289 (74) Representative: Engisch, Gautier et al BVBA Procter & Gamble Europe SPRL, (71) Applicant: THE PROCTER & GAMBLE COMPANY Temselaan 100 Cincinnati, Ohio 45202 (US) 1853 Strombeek-Bever (BE) (54) Method for making acetal compounds (57) A method for making an acetal compound is ed from the group consisting of an aldehyde, a ketone, disclosed, comprising the steps of: (a) adding a carbonyl and mixtures thereof; and (b) pressurizing the mixture compound, an alcohol, and a dehydrating agent to an of step (a), wherein the pressurization causes the carb- environment wherein the carbonyl compound is select- onyl compound and the alcohol to react and form the acetal compound. < o O) o a. LU Printed by Jouve, 75001 PARIS (FR) EP0 905 115 A1 Description FIELD 5 [0001] The present invention relates to a method for making acetal compounds. BACKGROUND [0002] Acetal compounds are known in the art and have been widely used in many industries, for example, in the 10 manufacture of pharmaceutical products and detergent products, and in the fragrance and lacquer industries. The term "acetal compound" is widely used to encompass both acetals derived from an aldehyde and an alcohol, and ketals derived from a ketone and an alcohol. Certain methods for making acetal compounds are also known in the art. [0003] Conventional methods for making acetal compounds derive the acetal compound from an aldehyde and an alcohol with an acidic catalyst under reflux. The use of dehydrating agents (e.g., molecular sieves) for removal of water is during such a reaction is also known in the art. Removal of water obtained from such a dehydration reaction tends to shift the reaction equilibrium to the right, meaning that the reaction proceeds to derive the resulting acetal compounds from the starting compounds. Generally, Dean-Stark apparatus is used for carrying out the dehydration reaction in the formation of esters or acetals. See Synthesis, vol.7, pages 501-522, 1981, "Methods for the Preparation of Acetals from Alcohols or Oxiranes and Carbonyl Compounds," issued by Frans A.J. Meskens. 20 [0004] Certain alcohols such as low boiling point alcohols and unstable alcohols, however, may not be suitable for such known methods using the dehydration reaction (e.g., acetal formation by Dean-Stark apparatus). Alcohols having low boiling points tend to volatilize during a reaction under reflux. The loss of the alcohol by such volatilization results in a much lower yield of the acetal compound as compared to the theoretical yield of acetal compound. [0005] Herein, "unstable alcohol" means an alcohol which tends to decompose or degrade at high temperature in 25 the acetal formation, especially in the existence of acidic catalysts under reflux. Generally, the harsher the condition (e.g., high temperature, high pressure, etc.), the shorter the time required for the reaction, thereby the reaction can proceed more effectively, with high yield. However, if the reaction for the acetal formation using conventional methods (e.g., by Dean-Stark apparatus) is carried out under harsh conditions, the use of unstable alcohols may cause unde- sirable chemical reaction between components, and/or decomposition or degradation of the starting components during 30 the reaction under reflux, especially in the existence of an acidic catalysis. [0006] In the use of such alcohols for acetal formation, two-step reactions may be considered instead of one-step reactions. The term "one-step" reaction means that the proposed compound is derived from starting components di- rectly; in a "two-step" reaction, the proposed compound can not be directly derived. For example, a dialkyl acetal (e. g., dimethyl acetal) wherein the alkyl unit has a short carbon chain length (e.g., methyl) is obtained by the first step. 35 The alkyl unit obtained is then substituted during the second step to obtain the proposed acetal. However, due to the need for multiple steps and much longer the reaction time, two-step reactions are generally less desirable than one- step reactions. [0007] Consequently, the use of unstable alcohols in conventional methods for acetal formation typically result in undesirable low purity and yields of acetal compounds, or the acetal compounds may not be obtainable at all. 40 [0008] Based on the foregoing, there is a need for a method to obtain acetal compounds directly from carbonyl compounds and alcohols, including unstable alcohols, with high purity and yield of the acetal compound. There is also a need to facilitate the reaction, such as by reducing the number of reaction steps and the reaction time. None of the existing art provides all the benefits of the present invention. 45 SUMMARY [0009] The present invention is directed to a method for making an acetal compound comprising the steps of: (a) adding a carbonyl compound, an alcohol, and a dehydrating agent to a sealable environment wherein the carbonyl compound is selected from the group consisting of an aldehyde, a ketone, and mixtures thereof; and (b) pressurizing so the mixture of step (a), wherein the pressurization causes the carbonyl compound and the alcohol to react and form the acetal compound. [0010] These and other features, aspects, and advantages of the present invention will become better understood from a reading of the present disclosure. 55 DETAILED DESCRIPTION [0011] While the specification concludes with claims particularly pointing out and distinctly claiming the invention, it is believed that the present invention will be better understood from the following description. 2 EP0 905 115 A1 [0012] The following is a list of definitions for terms used herein. [0013] "Acetal compound" includes a compound derived from a starting carbonyl compound and an alcohol; acetals derived from aldehydes and alcohols; and ketals derived from ketones and alcohols. [0014] "Carbonyl compound" means a compound having at least one carbonyl unit, including aldehydes, ketones, 5 and carboxylic acids having -COOR unit; preferably, aldehydes or ketones. [0015] "Alkyl" means a carbon-containing chain, which may be straight, branched, saturated, or cyclic; substituted (mono- or poly-) or unsubstituted. [0016] "Alkenyl" means a carbon-containing chain, which may be straight, branched, unsaturated, or cyclic; substi- tuted (mono- or poly-) or unsubstituted. 10 [0017] "Aryl" means an aromatic; substituted (mono- or poly-) or unsubstituted. [0018] "Aralkyl" means arylalkyl which has the structure Ft' -Ft"-, wherein Ft' is an aryl and Ft" is an alkyl. [0019] "Alkoxyl" means alkyloxy which has the structure R-O-. [0020] "Polyalkoxylate" means -(R-0)n-, wherein n is an integer. [0021] "Amine" means R-NH2. 15 [0022] "Amide" means R'-CONH2 or R'-CONH-R", wherein Ft' and Ft" is independently alkyl or aryl. [0023] "Ester" means R'-COO-R", wherein Ft' and Ft" is independently alkyl or aryl. [0024] "Ether" means R'-O-R", wherein Ft' and Ft" is independently alkyl or aryl. [0025] "Comprising" means that other steps and other components which do not affect the end result can be added. This term encompasses the terms "consisting of and "consisting essentially of." 20 [0026] All percentages and ratios used herein are by weight of total composition, unless otherwise indicated. [0027] All measurements referred to herein are made at 25°C unless otherwise specified. [0028] All percentages, ratios, and levels of ingredients referred to herein are based on the actual amount of the ingredient, and do not include solvents, fillers, or other materials with which the ingredient may be combined as a commercially available product, unless otherwise indicated. 25 [0029] All publications, patent applications, and issued patents mentioned herein are hereby incorporated in their entirety by reference. Citation of any reference is not an admission regarding any determination as to its availability as prior art to the claimed invention. [0030] The present invention relates to a method for making an acetal compound comprising the steps of: (a) adding a carbonyl compound, an alcohol, and a dehydrating agent to a sealable environment wherein the carbonyl compound 30 is selected from the group consisting of an aldehyde, a ketone, and mixtures thereof; and (b) pressurizing the mixture of step (a), wherein the pressurization causes the carbonyl compound and the alcohol to react and form the acetal compound. [0031] The method of the present invention can be used for the formation of acetal compounds wherein conventional methods [e.g., using Dean-Stark apparatus) have been useful, but have typically required longer reaction times and/ 35 or typically have resulted in low purity and lower yields of acetal compounds. The acetal compounds derived from the method of the present invention can be used for a variety of the products in different industries, and are particularly useful as pro-fragrance acetals in detergent compositions, which are designed to readily disperse in aqueous solution, deposit on fabrics, and release perfume. Herein, "pro-fragrance" compound means a compound which may or may not be odoriferous in itself but which, upon hydrolysis, produces a desirable odor which is characteristic of one or more 40 of its hydrolysis products. ACETAL COMPOUNDS [0032] The acetal compounds of the present invention, including a acetal and a ketal, have following general formula: 45 V R2— C— X I Y 50 [0033] R1 and R2 are independently, alkyl, alkenyl, aryl, or aralkyl.