Es wird die Darstellung eines Palladium‐Blei‐Katalysators und seine Anwendung für einige Partialhydrierungen unter Erhaltung aliphatischer Doppelbindungen beschrieben.

Palladium catalyst for partial reduction of acetylenes product: 0.10 g. of the palladium solvent: 15 ml. of olefin‐free petroleum ether

The industrial β‐carotene manufacturing procedure based on Inhoffen's synthesis C19 + C2 + C19 = C40 is described. β‐Ionone is first lengthened to β‐C14‐aldehyde as in our vitamin A‐synthesis. By acetalisation, condensation with vinyl ether and treatment with acid the new β‐C16‐aldehyde is obtained. Repetition of the same reactions with propenyl ether leads to the β‐C19‐aldehyde. For the final steps simple methods were developed giving high yields. All the chemical, physical and biological constants of synthetic β‐carotene are identical with those of the natural compound. Exact data on light absorption are given. Extensive experiments with the synthetic β‐carotene on rats and rabbits show that even very large doses have no toxic effects.

A simple and efficient synthesis of lycopene is described based on stepwise lengthening of a symmetrical C10‐dialdehyde as central component. This C10‐dialdehyde is lengthened at both ends, first with vinyl ether and then with propenyl ether, leading to a C20‐dialdehyde which is transformed into crocetin dialdehyde by partial hydrogenation of the central triple bond. By means of a new reaction devised by Wittig, crocetin dialdehyde is condensed at both ends with geranylidene‐triphenylphosphorane and lycopene is obtained according to the scheme C10 + C20 + C10 = C40. This synthetic pigment is identical with pure natural lycopene isolated from tomato juice. The Wittig reaction also allows a new β‐carotene synthesis using the components cyclogeranylidene‐triphenylphosphorane and 8,8′‐dehydro‐crocetin dialdehyde.

Voluineii XLII, Fasciculus VI (1950) -S o . 211-212 1045 ttre fractioiinCe B son tour par Cvaporation et cristallisation 5 3.4"; les deus fraction.;ainsi obtenues peuvent &re reintroduites dans les dries de fractionnement.Des essais de sCparation des terres cCriques par cristallisation fractionn6e des sels Na[R-Cdta] montrent cependant que l'yttrium contenu dans ces mClanges s'accumule dans les eaux-mkres avec le lanthane, ce qui provoque des complications4). Le pro-cCdC de fractionnement par cristallisation des sels Na[R-Cdta] est moins favorablc que le procCdC en cycle utilisant les conipos6s NH4[R-6dtai 5 ) .