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公开(公告)号：DE50100896D1
公开(公告)日：2003-12-11
申请号：DE50100896
申请日：2001-08-25
Applicant: BASF AG
Inventor： THERRE DR , KAIBEL DR , AQUILA DR , WEGNER DR , FUCHS HARTWIG
IPC: C07C41/50 , C07B61/00 , C07C41/56 , C07C41/58 , C07C43/303
Abstract: Preparation of acetals by reaction of 1 mol. of an unsaturated aldehyde with 1 mol. of an unsaturated alcohol in presence of an acid as catalyst and with separation of the water of reaction is effected by partly reacting the reactants in a column, concentrating the obtained acetal in ≥ 2 sequential evaporation steps and then recycling the recovered reactants to the reaction column. Preparation of acetals (I) by reaction of 1 mol. of an unsaturated aldehyde (II) with 1 mol. of an unsaturated alcohol (III) in presence of an acid as catalyst and with separation of the water of reaction is effected by partly reacting the reactants in a column, concentrating the obtained acetal in ≥ 2 sequential evaporation steps and then recycling the recovered reactants to the reaction column. R - R = H or optionally substituted 1-6C alkyl; and R = H, an optionally mono- or poly-unsaturated, optionally substituted 1-12C alkyl or an optionally substituted 3-12-membered optionally mono- or poly-unsaturated carbon ring.
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公开(公告)号：DE59904210D1
公开(公告)日：2003-03-13
申请号：DE59904210
申请日：1999-09-17
Applicant: BASF AG
Inventor： THERRE DR , KAIBEL DR , AQUILA DR , WEGNER DR , FUCHS HARTWIG
IPC: B01J27/16 , C07B61/00 , C07C41/28 , C07C43/15 , C07C45/37 , C07C45/51 , C07C45/54 , C07C45/67 , C07C47/21 , C07C49/203
Abstract: Preparation of citral (I) comprises thermal decomposition of 3-methyl-2-buten-1-al-diprenylacetal and rearrangement of obtained intermediates cis/trans-prenyl-(methyl-butadienyl)-ether (IV) and 2,4,4-trimethyl-3-formyl-1,5-hexadiene (V). (IV) and (V) are continuously distilled off and converted into (I) before or after removal of by-product prenol. Preparation of 3,7-dimethyl-2,6-octadien-1-al (citral) of formula (I) comprises: (1) thermal decomposition of 3-methyl-2-buten-1-al-diprenylacetal of formula (II) optionally in the presence of an acid catalyst to split off 3-methyl-buten-1-ol (prenol) of formula (III) and form cis/trans-prenyl-(methyl-butadienyl)-ether of formula (IV); (2) Claisen rearrangement of (IV) to give 2,4,4-trimethyl-3-formyl-1,5-hexadiene of formula (V); and (3) Cope rearrangement of (V) to form (I). The transitionally formed (IV) and (V) and the desired citral as well as the prenol (III) are continuously distilled out of the reaction mixture and (IV) and (V), before or after distillative separation of (III) and optional by-products, are subjected to rearrangement to form (I) at 100-200 degrees C.
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