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1. Seventeen cases of hepatic porphyria have been studied with respect to variations in isomer composition of the urinary Waldenström uroporphyrin complex. 2. Comparison was made of the effect of various isolation procedures on the isomer composition of the uroporphyrin complex, with special reference to the effect of preliminary heating of the urine. 3. Methods not employing heat, including the ethyl acetate extraction procedure of Waldenström, the talc adsorption of Grinstein et al., and a number of modifications, usually yielded relatively small amounts of a uroporphyrin complex, preponderantly Type I isomer. In two instances, however, the complex contained 60-70 per cent Type III. When separable on calcium carbonate, the Type III component was again shown to consist in the main of a 7-COOH porphyrin. Preheating of the urine regularly produced much larger amounts of a Waldenström type porphyrin, and larger proportions of Type III isomer in the complex. 4. The Waldenström porphyrin isolated following conversion of naturally occurring porphyrinogen, by irradiation with ultraviolet light, usually contained a marked preponderance of uroporphyrin I. In certain instances, however, the porphyrinogen was entirely that of the "208" Type III porphyrin. 5. While the large amount of Type III porphyrin found after heating the urine undoubtedly represents nonenzymatic conversion of porphobilinogen, the smaller amount of Type I isomer usually present in major proportion in the preformed uroporphyrin complex or its porphyrinogen may have intrinsic metabolic significance. In exceptional cases of acute porphyria, the uroporphyrin of the unheated urine is preponderantly the Type III isomer.

Enyne-hydrocarbons, -alcohols and -ethers with the system CH&=C-C=C< can be converted into the isomers with a terminal acetylenic group HC=C-C=C-C<, by treating them with an excess of potassium amide in liquid ammonia and hydrolysing the reaction mixture thus formed. In most cases yields are excellent. Enyne thioethers RC=C-CH=CH-SCeHs (R = alkyl) undergo an elimination of ethanethiol under these conditions. Hydrolysis affords the 1,3-diynes RC=C-C=CH in very good yields.The conversion of 1-propynyl compounds, CH3C = C-R, into the monosubstituted acetylene derivatives, HC = C-CHz-R, can be realized by the action of an equivalent quantity of alkali amide 112 in liquid ammonia or in an organic solvent, and subsequent hydrolysis of the reaction mixture:C H~C E C -R i-NaNHz (or KNHa) +. CHa-CIC-R +. CH=C=CH-R + .

Reaction of p-ionone with the dienynyl ether V under Neff conditions affords the CZO carbinol VI, from which vitamin A aldehyde VIII can be prepared by reduction with lithium aluminium hydride and subsequent hydrolysis of the complex of the reduced CZO carbinol with dilute acids.The dienynyl ether is synthesized from the acetal CH3COCHzCH(OCH& by addition of propynyl-lithium, subsequent reaction of the resulting C7 carbinol I1 with ethyl vinyl ether to yield the C7 diacetal Ill and treatment of the latter with alkali amide in liquid ammonia. The overall yield of the dienynyl ether V is about 75%, while vitamin A aldehyde is obtained in yields of 55-60%, calculated on 8-ionone. Among the syntheses of vitamin A derivatives * hitherto known there are few only in which the skeleton of the twenty carbon atoms is built up with good yields in a one step reaction from b-ionone.Applying the syntheses of 1,3-enyne derivatives recently developed in our laboratory 1 , 2 7 3 , 4 , we have succeeded in preparing easily the dienynyl ether The first step in the preparation of the dienynyl ether V is a Neff reaction between propynyl-lithium and the commercially available ketobutyraldehyde dimethylacetal (I) (yield 90 %):For a review on syntheses of vitamin A and carotene derivatives see: 0. Isler and P. Schudel, "Advances in

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