Manuel M. Baizer

Electrocarboxylation. I. Mono- and dicarboxylation of activated olefins

Aus den aktivierten Olefinen (I) wie Acrylester, Vinylmethylketonoder Acrylnitril erhalt man bei der elektrolytischen Reduktion an der Quecksilber-Kathode uber das Radikal-Anion (II) mit Kohlendioxid das Radikal-Anion (IV), das zum Dianion (V) reduziert und mit Kohlendioxid in das Bis-carboxylat (VI) ubergefuhrt wird.

Electrolytic Reductive Coupling II . Derivatives of Mono‐Olefinic α, β‐Unsaturated Acids

Electrolytic hydrodimerization of a variety of derivatives of α, β‐unsaturated acids is reported, e.g., methacrylonitrile, cinnamonitrile, ethyl acrylate, ethyl maleate, di‐2‐ethylhexyl fumarate, N, N‐diethylacrylamide, acrylamide. The double bond may be endocyclic, as in 1‐cyano‐1‐cyclopentene. The relationship of structure to hydrodimerizability is discussed. Evidences of stereo‐preference in electrolytic hydrodimerization are presented.

Electrolytic Reductive Coupling XVIII . Hydrodimerization of Activated Olefin A vs. Cross‐Coupling with Activated Olefin B as a Function of Cathode Voltage

It is shown that in mixed reductive coupling of activated olefins A and B, in which A is reduced at the more anodic voltage, the ratio of cross‐coupled product HABH to self‐coupled product HAAH rises substantially as the controlled potential is made more negative. Diethyl maleate (DEM) was chosen as an example of A and ethyl acrylate (EA) and acrylonitrile (AN) as examples of B. Previously reported fluctuations of voltage along the cathode surface are confirmed and may lead to unexpected formation of HBBH. The results of cyclic voltammetry of DEM in the presence of EA or AN and of a kinetic study of the addition of a carbanion to these same acceptors in bulk are interpreted to indicate that the reductive coupling of DEM with the acceptors occurs largely but not exclusively at the electrode surface.

Paired Electro‐Organic Syntheses I . Cathodic Adipate with Anodic Bimalonate

A procedure is reported for the co‐electrolysis of ethyl acrylate and diethyl malonate using as solvent/electrolyte system to yield diethyl adipate and tetraethyl ethane‐1,1,2,2‐tetracarboxylate in high (95%) yield and good (60%) current efficiency. A convenient cell which allows experimentation in the 2–5g range was fabricated from a hollowed‐out graphite cylinder (optionally lined with lead) which served as one electrode and a graphite rod machined and held so as to be counterelectrode and mechanical stirrer. General aspects of paired organic syntheses are discussed as well as the specific problems that are involved when the paired reactions are hydrodimerization‐dehydrodimerization.

Electrolytic Reductive Coupling XVII . A Study of 1,2‐Diactivated Olefins. Part II . Macro‐electrolyses

The electrolytic reductive coupling of a variety of diactivated olefins, , has been studied. The reduced dimeric products have been isolated and carefully identified. Both symmetrical and unsymmetrical dimers were observed. The dimeric products are formed by two paths: the first involves the attack of the electrochemically generated anion radical on unreduced olefin; the second involves the protonation of the anion radical followed by reduction to an anion and subsequent attack on the olefin. The isomer distribution in the dimeric product obtained by the first route is rationalized on the basis of the relative anion stabilizing ability of the activating groups in the acceptor molecule and the relative ability toward stabilizing a radical site in the donor molecule. The possibility of forming cross‐coupled products (between a diactivated olefin and a Michael acceptor) is limited to systems in which the electrochemically generated anion radical is relatively stable toward its parent olefin or in which the reduction potentials of the pair are similar, i.e., .

Electrolytic Reductive Coupling XIX. Effect of Counterions in Cathodic Reactions of 1,2‐Diactivated Olefins

Certain 1,2‐diactivated olefins XCH=CHY (I) in which X and Y are electron‐withdrawing groups not themselves reduced under the conditions used were electrolyzed in the presence of counterions (M+) chosen from the group Li+, Na+, K+, Rb+, . Cyclic voltammetric techniques permitted the measurement of the change in rate of decomposition of the anion radical as M+ was varied. Bulk electrolyses yielded reduced coupled products whose identity and distribution varied with changes in M+.

Electrolytic reductive coupling as a synthetic tool

Abstract The utility of electrolytic reductive coupling as a means for synthesizing a variety of polyfunctional compounds is discussed. Activated olefins function as acceptors towards donors generated by electrolytic induction of (a) other activated olefins, (b) other activated olefinic groups within the same molecule, (c) compounds containing “leaving groups” and (d) azo-compounds and Schiff bases.

Recent developments in electro-organic synthesis

ConclusionsThere has been no better time than the present to initiate or continue research in electro-organic synthesis. The past decade has seen truly gigantic advances in the organization of sources of information, in the development of equipment and techniques, in the elucidation of principles, and in the achievement of significant results. Much remains to be done.It may seem somewhat foolhardy for an industrial chemist to invite fierce competitors to enter the lists. But I have sure knowledge that only a finite number of people will be arrayed against an infinite number of challenges. It is not difficult for each combatant to choose a fresh, stubborn adversary and to avoid merely giving the coup de grâce to a problem that has already been mortally wounded.Electro-organic synthesis is becoming more of a science and less of an art. This need not detract from the glamour and mystery of working in this field. As in every scientific endeavour, the solution of a challenging problem brings with it a sense of aesthetic fulfillment.

NEWER METHODS FOR OLIGOMERIZING OLEFINIC MONOMERS

The past several years have seen intensive research and development on a number of novel methods for producing dimers and reduced dimers, oligomers and reduced oligomers from olefinic starting materials.’ The products have generally been desired as raw materials for the manufacture of wellestablished large-volume polymeric products; in some cases, the efficiency of the oligomerization process has economically produced dimeric products for which commercial outlets are still being sought; in a few instances the oligomers have been made for the purpose of elucidating the intermediate steps in a polymerization process. A complete survey of the newer methods under discussion would include at least: (a) alkali metal-amalgam reduction of activated olefins, (b) electrolytic reduction of activated olefins, (c) catalysis by tert-phosphines, (d) catalysis by organometallic intermediates, and (e) oligomerization by heat treatment, This review will deal with methods (a), (b), and (c), with which the writer is most familiar. This limitation is not meant to deprecate the importance of (d) and (e): The dimerization of propylene by potassium (via ally1 potassium) has yielded 4-methyl-l-pentene,’ raw material for very interesting new ’ polymers; the dimerization of ropylene to 2-methyl-1 -pentene3 using trialkyl-aluminum

Tetra-alkylammonium cyanides as nucleophilic and basic reagents

The title compounds catalyse the dimerization and polymerization of activated olefins, the Michael reaction, and other base-catalysed reactions. The mechanism of these reactions is discussed in relation to that of the similar tertiary-phosphine-catalysed reactions. Nucleophilic behaviour is inferred in the dimerization and polymerization reactions, and basic behaviour in olefin isomerization. Under comparable conditions the title compounds are more powerful nucleophiles (towards alkyl halides) than sodium cyanide.