Abstract: o,o'-Dithiodibenzamides of the formula ##STR1## where R.sup.1 and R.sup.2 are each hydrogen, alkyl or phenyl, R.sup.3 is hydrogen, halogen, nitro, methyl or methoxy, and R.sup.4 has the same meanings as R.sup.3, are prepared by nitrosating an anthranilamide of the formula ##STR2## and reacting the product with sulfur dioxide in the presence of copper or a copper salt.

Abstract: 3-Hydroxy-.alpha.-cyclocitral derivatives of the general formula I ##STR1## where R.sup.1 is ##STR2## wherein R.sup.2 and R.sup.3 can be identical or different and are each straight-chain or branched alkyl of 1 to 6 carbon atoms, or R.sup.2 and R.sup.3 together form an ethylene or propylene group which can be substituted by methyl or ethyl, processes for their preparation and their use for the preparation of safranal and 3-hydroxy-.beta.-cyclocitral, as well as optically active - cyclocitral derivatives of the general formulae A and B ##STR3## where R.sup.1 is ##STR4## if X is hydrogen and Y is OH, but is otherwise ##STR5## where R.sup.2 and R.sup.3 have the above meanings, and X and Y together are oxygen, or X is hydrogen if Y is OH, and a process for the preparation of optically active 3-oxo-.alpha.-cyclocitral acetals, wherein a mixture of the corresponding racemic 3-oxo-.alpha.-cyclocitral acetals is separated into the optically active compounds by chromatography over a suitable chiral adsorbent.

Abstract: o,o'-Dithiodibenzoic acids are prepared by a process wherein a diazotized anthranilic acid or anthranilate is reacted with sulfur dioxide in the presence of an acid, water and a copper salt, and if desired in the presence of an alkali metal iodide, in a 1st stage at from 20.degree. to 50.degree. C. and then in a 2nd stage at from 80.degree. to 100.degree. C.The o,o'-dithiodibenzoic acids obtainable by the process of the invention are useful starting materials for the preparation of crop protection agents, dyes and drugs.

Abstract: A process for the preparation of saccharin by reacting an aqueous hydrochloric acid solution of o-methoxycarbonylbenzenediazonium chloride with sulfur dioxide, wherein(a) the aqueous diazonium salt solution is reacted with sulfur dioxide at from 0.degree. to 100.degree. C. in the presence of a water-immiscible or only partially water-miscible inert organic solvent,(b) in order to decompose the diazonium salt, the reaction mixture is treated simultaneously or subsequently with a diazonium salt decomposition catalyst,(c) the aqueous organic reaction mixture, or the organic phase obtained after removing the aqueous phase, is treated with an oxidizing agent at from 0.degree. to 100.degree. C. and(d) the organic phase is reacted with aqueous ammonia at from 0.degree. to 50.degree. C. and the saccharin is isolated from the aqueous phase in a conventional manner by acidifying with a strong acid.

Abstract: A process for the preparation of aromatic sulfohalides by reacting an aqueous solution, containing a hydrogen halide, of an aromatic diazonium halide with sulfur dioxide, wherein(a) the aqueous solution, containing the hydrogen halide, of a diazonium salt which is derived from the corresponding aromatic amine and the halogen of the desired sulfohalide is reacted with sulfur dioxide in the presence of an inert organic solvent which is immiscible or only partially miscible with water,(b) the diazonium salt is decomposed, simultaneously or subsequently, by means of a catalyst for diazonium salt decomposition and(c) the resulting reaction mixture, or the organic phase thereof after removal of the aqueous phase, is treated with an oxidizing agent.

Abstract: A process for the preparation of 6-membered cyclic acetals of trans-4-chloro-3-methyl-but-2-en-1-al by reacting the corresponding acetals of 3-methyl-but-2-en-1-al (prenal), in a halohydrocarbon, with sulfuryl chloride and for their subsequent oxidation to trans-3-methyl-but-2-ene-1,4-dial-1-monoacetals (3-methyl-fumarodialdehyde-1-monoacetals). The trans-3-methyl-but-2-ene-1,4-dial-1-monoacetals are of great importance in terpene syntheses, since they make it possible to carry out successive Wittig reactions giving a very large number of compounds of biological and pharmacological importance.

Abstract: A process for the preparation of polyene-aldehydes, derived from 2,6-dimethyl-2,4,6,8-nonatetraen-1-al by substitution in the 9-position, by means of the Wittig ylide synthesis. The process is based on the observation, contrary to all expectation, that on reacting 2,6-dimethyl-octa-2,4,6-triene-1,8-dial with an equimolar amount of an ylide, it is exclusively the 8-al group of the dialdehyde which reacts. This specificity of the reaction is of particular importance for the preparation of the food dye .beta.-apo-8'-carotinal.

Abstract: 3-Chloro-3-methyl-butane-1,4-dial-bis-acetals and 3-methyl-but-2-ene-1,4-dial-bis-acetals are obtained by reacting a six-membered cyclic acetal of 3-methyl-but-3-en-1-al with an alkyl nitrite in the presence of methanol and hydrogen chloride and, if desired, eliminating HCl in the conventional manner.The butanedial-bis-acetals and butenedial-bis-acetals are valuable intermediates through which the trans-3-methyl-but-2-ene-1,4-dial-1-acetals, which are sought-after products for terpene syntheses, can be obtained in an industrially particularly advantageous manner.

Abstract: Process for the manufacture of canthaxanthin by oxidizing .beta.-carotene, retro-dehydro-carotene or echinenone with a salt of chloric or bromic acid in the presence of a catalyst and of an inert diluent or solvent.

Abstract: A process for introducing an allyl-positioned carbonyl group into a 2,6,6-trimethylcyclohexene ring which carries a polyenyl radical in the 1-position, by oxidizing the ring with a halogen(V)-oxyacid or a salt of such an acid, and the new oxo compounds obtainable by the said process, which may be used as dyes for foodstuffs or cosmetics. The oxidation is carried out in the presence of a catalyst and of an inert diluent or solvent, in an acid medium. Suitable catalysts are bromine and iodine and the oxides of elements of groups Va, VIa, VIIa and VIII of the periodic table.

Abstract: New acetals, containing a 6-membered ring, of 2-methyl-2,4-dialkoxy-3-buten-1-al, are obtained by reacting the corresponding 2-methyl-2-alkoxy-3-butyn-1-al-acetals with a mixture of the appropriate alcohol and an alkali metal alcoholate of the said alcohol at from 100.degree. to 200.degree. C. The acetals are intermediates for the preparation of carotinoid-based physiologically safe food dyes.

Abstract: Echinenone is produced by oxidizing .beta.-carotene or retro-dehyro-carotene with iodic acid or a salt of iodic acid in the presence of a catalyst and of an inert diluent or solvent.