Podbielniak column

The checkers used an 18-in. Podbielniak column with simple wire spiral, heated jacket, and partial-reflux head. 

If no separation of isomers is required, as when the mixture is to be hydrogenated, the mixed esters may be obtained by distillation yield, 75-90 g. (71-85%, based on starting aldehyde). It is extremely difficult to separate the A2- from the A3-ester by fractional distillation, as the two boil only 7° apart however, by careful fractionation and refractionation through an 0.8 X 125-cm. simple Podbielniak column with partial-reflux head,4 it is possible to obtain 3 pure ethyl 4-ethyl-2-methyl-2-octenoate, b.p. 102-103°/4.8 mm., o 1.4478, and a nearly pure sample of ethyl 4-ethyl-2-methyl-3-octenoate, b.p. 94-95°/4.8 mm., ng 1-4393. 

When the checkers distilled the product through a simple type of Podbielniak column of 65-cm. length, with heated jacket and partial reflux head, the boiling range was 1°, 74-75°/6 mm., but the yields and index of refraction were the same as those reported by the submitters. 

Purification. a-Methylstyrene was purified by distillation through a 6-foot, Heli-grid-packed, modified Podbielniak column under a reduced pressure of dry helium. Purity of the distillate was established by vapor phase chromatographic analysis, using flame ionization detection and an appropriate column. Sample purity generally ranged from 99.90 to 99.98%. 

Irone (6-methyl-ionone, -trans-(a)-4/-[2,5,6,6-tetramethyl-cyclohex-2-yl]but-3z-en-2-one) [79-69-6] M 206.3, b 85-86°/0.05mm, 109"/0.7mm, dj 0.9340, n, 1.4998. If large amounts are available then fractionate through a Podbielniak column or an efficient spinning band column, but small amounts are distilled using a Kiigelrohr apparatus. The 4-phenyl-semicarbazone has m 174-175° (165-165.5°). [IR Seidel and Ruzocka HCA 35 1826 1952-, Naves HCA 31 1280 1948. Lecomte and Naves J Chimique Physique 53 462 1956]. 

The checkers employed a Podbielniak column, 0.8 x 125 cm., with tantalum wire spiral and partial reflux head.3... 

The submitters used a 24-cm. jacketed Vigreux column for this distillation. The checkers used a simple type of Podbielniak column, 50 cm. in length, with heated jacket and partial reflux head after the last of the benzene had been distilled through the column, the following fractions were received ... 

Dissolve in Et20, dry (CaCl2), evap and distil through a short column. Distillation through a Podbielniak column led to decomposition. Store in the dark under N2, preferably in sealed ampoules. Even at -10° it slowly decomposes. [JACS 76 6054 1954. ... 

A simplified Podbielniak column was employed.3 Other columns of comparable efficiency should be suitable. 

The submitters used a simple type of Podbielniak column.3 The checkers used a 122-cm. column of similar design. 

A 50 cm. by 8 mm. simple Podbielniak column 2 with partial-reflux head is adequate for this and subsequent distillations. 

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