Now in bead form for chromatography of biologic substances...
Birch reduction produces dimers
Sephadex Ion Exchangers Because of its advantages—stability and inertness—Sephadex has been used to produce a new class of ion exchangers: DEAE-, CM- and SE-Sephadex. Since their introduction they have been used extensively, particularly in the biochemical and clinical field. In the new bead form they will be more useful both for laboratory and manufacturing scale processes. Their spherical shape gives increased mechanical strength and leads to easier column packing. More uniform particles result in improved hydrodynamic properties. All Sephadex Ion Exchangers have a high capacity and low nonspecific adsorption. They are available in two types that differ in porosity, thus offering flexibility for your specific requirements. Sephadex Ion Exchangers are of analytic grade purity and are produced under rigorous quality control, thus ensuring uniform products to give accurate and reproducible results. ng/ml lOOr
Pril , en,%T2537A Hexose mono phosphates " u - ^ o - r * . ^
Various dimeric products may accompany the amines which are made via the Birch reduction of certain polynuclear hydrocarbons, Dr. E. J. Eisenbraun, of Oklahoma State University, told the ACS Southwest Regional Meeting at Albuquerque, N.M. He said that reductive amination occurs in the reaction of substances such as naphthalene with sterically unhindered amines in the presence of sodium. But he also isolated some dimeric hydrocarbons from the reaction mixtures in his studies. The Birch conditions—sodium in liquid ammonia—reduced naphthalene primarily to 1,2-dihydronaphthalene and 1,2,3,4-tetrahydronaphthalene. Dr. Eisenbraun explains that he began to use higher-molecular-weight amines to study the role of the N—H bond and to keep the reaction conditions near room temperature instead of having to condense large volumes of ammonia. As a result, Dr. Eisenbraun, along with Dr. R. C. Bansal of Oklahoma State University and Dr. P. W. Flanagan of Continental Oil Co., Ponca City, Okla., obtained 5 5 % of N-(l,2,3,4-tetrahydro-2-naphthyl) perhydroazepine from the Birch reduction of naphthalene with hexamethylenimine and sodium. Only 13% of 1,2-dihydronaphthalene and 20% of 1,2,3,4-tetrahydro-
naphthalene were obtained. But they got some dimeric hydrocarbons from the reaction mixture. Dr. Eisenbraun says that the amine could arise by one of two possible routes: The amine could add to the aromatic system followed by reduction of the aminated ring, or partial reduction of the aromatic hydrocarbon followed by addition of the amine. The Oklahoma group found the partial reduction course to be correct because the aminated product arose from the reaction with 1,4-dihydronaphthalene itself. By deuterium studies, the Oklahoma chemists determined the source of protons in the reduction to be the amine function. The generally accepted mechanism for metal-amine reductions, according to Dr. Eisenbraun, is that naphthalene is first reduced to 1,2-dihydronaphthalene. This product is attacked by the amine ion to yield the reductive amination product. In turn, the dihydronaphthalene may be further reduced to 1,2,3,4-tetrahydronaphthalene. The overall reaction sequence is a competition between a Birch-type reduction and reductive amination. Some of the factors regulating the course of the Birch reduction are the temperature of the reaction mixture, the degree of alkylation of the polynu-
AMP
glycogen
Type of amine determines products of Birch reduction of naphthalene
glucose
~0
100
/ >J.i\i, w 200
300
Ethylenediamine gives higher yield of dimers
400 ml
Model experiment with glycogen, glucose, sugar phosphates and adenosine phosphates on a column of DEAE-Sephadex A-25. (From Biochim. Biophys. Acta 7 4 (1963) 5 8 8 , by permission of the author)
Anion Exchangers (Bead Form) Grade
Type
Ionic Form
Capacity (meq/g)
Ethylenediamine Metallic sodium
Bed Volume' (ml/g)
DEAESephadex A-25
40-1 20M
ci-
35 ±0.5
5-9
DEAESephadex A-50
40-120M
ci-
3.5 ± 0 . 5
25-33
Cation Exchangers (Bead Form) Type
Grade
lonic Form
Capacity (meq/g)
Bed Volume 2 (ml/g)
Na*
4.5 ± 0 . 5
6-10
CMSephadex C-25
40-120/x
CMSephadex C-50
40-120ft
Na*
4.5 ± 0 . 5
32-40
1 SESephadex C-25
40-120|i
Na*
2.3±0 3
5-9
SE[ Sephadex C-50 40-120^
Na*
2.3 ± 0 . 3
30-38
Hexamethylenimine results mainly in reductive amination product J
Hexamethylenimine ^
1. In Trls^HCl buffer, pH = 8.3. ionic strength = 0.05. 2. In sodium phosphate buffer*i>H = 6. Ionic s t r e n g t h = 0 . 0 6 .
For additional technical Information, booklet on Sephadex Ion Exchangers,
©
including write to:
P H A R M A C I A FINE C H E M I C A L S I N C . 800 Centennial Avenue. Piscataway, N.J. 08854 Pharmacia (Canada) Ltd.. 110 Place Cremazie, # S u i t e 412. Montreal 11. P. Q.
(Inquiries outside U.S.A. or Canada should be directed to PHARMACIA FINE CHEMICALS. Uppsala. Sweden.) 70
C & E N DEC. 12, 1966
Metallic sodium
N (OH *) Z'6
OCT (^^Y^^V-
*•{- Small amount of dimers
BROMINE Strange and wonderful things are happening with it No more is it just an anti-knock gasoline additive. Coming up: fresh new applications for bromine and its compounds. As fire retardants in plastics, textiles, wood, and paper products. As antimicrobial agents as well as chemical intermediates. As gravity separation media in metallic and nonmetallic mining operations. And we still haven't finished the list. Maybe you can develop an idea or two of your own. Perhaps we can help. And if you like, we'll fill you in on new uses, technical developments and process improvements that we've uncovered for bromine and bromine compounds. Without a doubt, even its oldest friends wouldn't know bromine these days. The Dow Chemical Company, Midland, Michigan.
DOW
O 1966,Chemetron Corporation
0.001 RESOLUTION
throughout 0.000 to 2.000 ABSORBANCE RANGE
.with the Gilford Model 3 0 0 MICRO-SAMPLE SPECTROPHOTOMETER WAVELENGTH RANGE 340 to 700 mu
SIMPLIFIED SAMPLING
This instrument maintains a usable resolution of 0.001 absorbance unit over its entire measurement span- of zero to 2.000 A. Its long term stability is better than 0.005 A per hour, requiring only occasional zero setting on a reference. And it combines this uncommon performance with explicitly simple operation. The automatic time-impulse sampling system draws less than 0.5 ml per sample with no handling of cuvettes or pouring of fluids. Touch a bar, and in a few seconds, you flush out the previous sample, then introduce the next. The absorbance value appears immediately on the four-digit numerical indicator. Or, after a single calibration setting, you can get direct readings of concentration in any convenient units. Technicians find the compact Model 300 especially easy to use and maintain. Yet here is a true spectrophotometer with research accuracy and flexibility, filling a realistic need in busy laboratories.
OIRECT REA00UT IN ABSORBANCE OR CONCENTRATION
72 C&EN DEC. 12, 1966
Write to Dept. C for a brochure and quotation. NSTRU~NETT LABORATORIES INCORPORATED O B E R i I N
OHIO
440/4
clear aromatic hydrocarbon, the presence or absence of functional groups, and the type of amine used. The type of hydrocarbon used is also important since naphthalene is readily animated and phenathrene, for example, is not. In considering the type of amine used, Dr. Eisenbraun notes, the steric hindrance of the amine determines whether amination or reduction takes place. Pyrrolidine gives 65 % of the animated naphthalene, while 2-methylpyrrolidine and 2,5-dimethylpyrrolidine give no animated product. On the other hand, hexamethylenimine gives 5 5 % and dipropylamine gives 7% of reductive amination product. Dr. Eisenbraun reasons that dipropylamine with loosely flexing alkyl groups would be more hindered about the N—H bond than hexamethylenimine, in which these groups are pinned back. In contrast to the secondary amines used in the reaction, primary amines react to yield dimerization products as well as the expected reduction and reductive amination products. For example, the reduction of naphthalene with sodium and ethylamine gives l,l',2,2',3,3',4,4'-octahydro-2,2'binaphthyl. The amount of cyclodimerization with diamines seems to be related to the distance between the amine functions, the Oklahoma State chemist says. Ethylenediamine and sodium provide an even more "interesting" product from reaction with naphthalene, he finds. There is good evidence that the major product is the partly hydrogenated binaphthylene. He says this was demonstrated when he carried out a series of reactions using sodium metal and a homologous series of diamines. The placement of alkyl substituents on the naphthalene ring has an important bearing on whether reductive amination occurs. The reaction does not take place if alkyl groups are placed at the 2,6 or 2,7 positions. As far as the metal employed is concerned, the reductive amination reactions appear to be restricted to sodium, except that potassium gives 4% yield of reductive amination product and polymeric hydrocarbon. Lithium and calcium, however, give no reductive amination products. They cause Birch-type reductions of naphthalene— 93% yield with lithium and 8 1 % with calcium. Dr. Eisenbraun indicates that reductive amination is a good method of synthesizing a tetralin system substituted at the beta position with a secondary or tertiary amino group. He adds that this method may become a very useful way to prepare molecules of interest to the pharmaceutical industry or as a general method for synthesis of amines.
