Cuprous bromide catalyst

Oxidation of a mixture of equivalent weights of the two low-molecular-weight homopolymers at 25°C with a diethylamine-cuprous bromide catalyst yielded a copolymer that formed stable solutions in methylene chloride and could not be caused to crystallize by stirring with a 3 1 methanol/toluene mixture, a procedure that results in crystallization of DMP homopolymer or of the DMP portion of DMP-DPP block copolymers. The NMR spectrum was identical with that of the polymer obtained by simultaneous oxidation of the two monomers. 

DMP homopolymer at the time the second monomer was added consisted of dead molecules, incapable of redistribution or of further normal polymerization. When the same procedure was followed, but with the less active diethylamine-cuprous bromide catalyst, only random copolymer was obtained, identical to that obtained by oxidation of the two monomers together. The same result was observed when DMP was oxidized with the diethylamine-cuprous bromide catalyst and tetramethyl-butanediamine-cuprous bromide was added along with DPP to increase the polymerization rate (Figure 5). 

Block copolymers were also produced by oxidizing mixtures of the two homopolymers. A summary of the effect of polymerization conditions on the structures of polymers prepared using equimolar amounts of the two monomers is presented in Table III. The preformed blocks used in these examples were a DMP homopolymer prepared with a diethylamine-cuprous bromide catalyst and a DPP polymer prepared with tetramethyl-butanediamine-cuprous bromide at 60°C. Each had an average degree of polymerization of approximately 50 units. 

Another way to get citronellol is by the reductive dimerization of isoprene with formic acid and triethylamine using a 1% pcdladium phosphine catalyst [32]. The two head-to-tail dimers are formed in up to 79% yields, which can easily be separated from the head-to-head and tail-to-tail dimers by conversion with aqueous hydrochloric acid, yielding 7-chloro-3,7-dimethyl-l-octene. Hydroboration and pyrolysis of this chloro derivative produces a 1 3-mixture of a- and jS-citronellol. The mono-chloro compound can also be oxidized with tert- mty peracetate and a cuprous bromide catalyst to the chloroacetate, which is reduced with LiAJH4 and pyrolyzed to linalool in 64% overall yield. 

The success of the Bart reaction when applied to nuclear- substituted anilines is often much affected by the pH of the reaction-mixture. Furthermore, the yields obtained from some m-substituted anilines, which under the normal conditions are usually low, arc considerably increased by the modifications introduced by Scheller, and by Doak, in which the diazotisation is carried out in ethanolic solution followed by reaction with arsenic trichloride in the presence of a cuprous chloride or bromide catalyst. 

Cuprous bromide, 44,12 Cuprous M-butylmercaptide, 42,22 Cuprous chloride as catalyst for 1,4 addition of Grignard reagents to <, (5-unsaturated esters, 41,63 Cyanoacetic acid, terl-butyl ester, 41,5... 

The cuprous bromide was used as obtained from E. H. Sargent Co. One instance of an ineffective batch of cuprous bromide from another source has been reported to the submitters. Cuprous bromide is only slightly soluble in the benzene solution. Greater amounts of catalyst have no effect on the yield of product. 

The reactivity of each of the phenols in homopolymerization was determined by following the rate of oxygen absorption in a closed system. In each case, a plot of oxygen absorption against time was linear over at least 80 of the total reaction. Measurements were made at 25°C with a cuprous chloride-pyridine catalyst ai d at 60°C with a more active catalyst, cuprous bromide-tetramethylethylenediamine (TMEDA). Relative rates, from the slope of the linear portion of the oxygen absorption curves, are summarized in Table I. DMP is about 30 times more reactive than DDP at 25° C and five times more reactive at 60° C. MPP is intermediate in reactivity (as expected from its structure) at both temperatures but is comparable at the lower temperature with DMP and at 60°C with DPP (about a third slower than DMP at 25°C and 50 faster than DPP at 60°C). 

The NMR spectra of copolymers prepared by simultaneous oxidation of the two phenols and those prepared by sequential oxidation, in either order, are almost identical. The methyl peak is broadened, as is the peak caused by the protons of the pendant phenyl rings centered at 8 7.20 ppm, and all show the same peaks for aromatic backbone protons in about the same intensity ratios. The polymer obtained by oxidizing a mixture of DMP and the separately prepared homopolymer of MPP with a cuprous bromide-tetramethylbutanediamine catalyst, the procedure considered to have the best chance of producing a block copolymer, was completely random. 

Oxidation of Mixtures of Monomers. The method most likely to yield random copolymers of DMP and DPP is the simultaneous oxidation of a mixture of the two phenols, although this procedure may present problems because of the great difference in reactivity of the two phenols. The production of high molecular weight homopolymer from DPP is reported to require both a very active catalyst, such as tetramethylbutane-diamine-cuprous bromide, and high temperature, conditions which favor carbon-carbon coupling and diphenoquinone formation (Reaction 2) from DMP (II). With the less active pyridine-cuprous chloride catalyst at 25 °C the rate of reaction of DMP, as measured by the rate of oxygen... 

A solution of 24 g of 4-(N,N-dimethylaminoethoxy)bromobenzene was added dropwise over 45 min to magnesium in 90 ml of anhydrous tetrahydrofuran. 2 ml of 1,2-dibromoethane were added as catalyst. After the addition, the mixture was stirred at 25°C for one hour to obtain a solution of 0.7 M of 4-(N,N-dimethylaminoethoxy)-benzene magnesium bromide which was then added to a solution of 6.16 g of dimethylsulfide-cuprous bromide complex in 20 ml of tetrahydrofuran. The mixture was stirred at room temperature for 20 min and a solution of 3.7 g of 3,3-[l,2-(ethanediyl-bisoxy)]-5a,10a-epoxy-17a-prop-l-ynyl-8(9(1 L))-estrene-17p-ol in 50 ml of tetrahydrofuran was added thereto dropwise over a few minutes. The mixture was stirred under an inert atmosphere for one hour and was then poured into a solution of 15 g of ammonium chloride in 20 ml of iced water. The mixture was extracted with ether and the organic phase was washed with aqueous saturated sodium chloride solution, was dried and evaporated to dryness under reduced pressure. The 18.3 g of oil were chromatographed over silica gel and eluted with chloroform to obtain 4.5 g of 3,3-[l,2-ethanediyl-bisoxy]-lip-[4-(N,N-dimethylaminoethoxy)phenyl]-17a-(prop-l-ynyl)-89-estrene-5a,17p-diol with a specific rotation of [a]D20 =-44(+/-)1.5° (c = 1% in chloroform). 

An additional functional group may be present in one of the reactants. Alkylation of vinylacetylene gives low yields of l-alken- ynes. - Cuprous halide catalyst is required for alkylations by allyl bromide the yields of l-alken-4-ynes are about 88%. Both halogen atoms of dibromides can be induced to take part in alkylation if the halogens are not on the same or adjacent carbon atoms. The yields of diynes are 46-85%. Diynes in... 

Birch and Smith found that cupric acetate is superior to the usuaUy used cuprous bromide as catalyst for the 1,4-addition of Grignard reagents to aj3-unsaturated ketones. Thus 19-nortestosterone (1) in the presence of cupric acetate adds methyl-magnesium iodide to give 2, derived from 1,4-addition, in high yield. 

Catalyst for 1,4-Grignard addition. With cuprous bromide as catalyst, methyl-magnesium bromide reacts with A < -octalone-2 exclusively by 1,4-addition to give 9-methyl-cH-decalone-2."... 

Grignard reaction catalysts Cobaltous chloride. Cupric acetate. Cuprous bromide. Cuprous chloride. 

In an improved process for the synthesis of tropilidene (5) by E. Muller, a solution of diazomethane in benzene is added gradually to refluxing benzene containing cuprous bromide as catalyst. Benzene is used in large excess, and the product is isolated most easily by filtering the solution from the catalyst and adding it to a solution of phosphorus pentachloride in carbon tetrachloride. The tropylium chloride which separates is dissolved in water and treated with perchloric acid to afford tropylium perchlorate in 85% yield. The success of the method is attributed to formation of the intermediate (3), a deactivated electrophilic carbon metal complex. Tropilidene... 

Copper bromide (CuBr) Copper monobromide Copper(l-i-) bromide Copper(l) bromide Cuprous bromide EINECS 232-131-6 HSDB 270. Used as a catalyst in organic reactions. Solid mp = 504° bp B 1345° d = 4.72 slightly soluble in H2O. Atomergic Chemetals Cerac Hoechst Celanese Sigma-Aldrich Fine Chem. 

Bromobenzene in methanol containing sodium methoxide in the presence of the catalysts sodium formate and cuprous bromide gave anisole in 56% yield after refluxing at 70°C for 7 hours (ref.65). 

Allenediynes. These compounds can be synthesized by coupling of allenic halides with butadiynyl(trimethyl)silane, with cuprous bromide as catalyst (equation I). This method was used for synthesis of a natural allenediynol... 

The various aspects of oxidative polymerization of phenols have been thoroughly reviewed. Most commonly PPEs are produced by the self-con-densation of a monovalent phenol in the presence of oxygen and a metal-amine-complex catalyst. Manganese, copper and cobalt can be used as the metal in the catalyst. Cu+ is most commonly utilized. For example, the preparation of the catalyst can be achieved by stirring cuprous bromide and di-n-butyl amine in toluene. ... 

Another early development of the Bart procedure was the use of diazonium fluoroborates instead of the more usual chlorides 144, 145). Subsequently Doak and Freedman 146) found that dry diazonium fluoroborates react with arsenic trichloride in dry ethanol to give both arsonic and arsinic acids. Under these conditions maximum yields of the arsonic acid are obtained using a cuprous chloride catalyst. In 80% ethanol quite high yields of the arsinic add are obtained using cuprous bromide as catalyst. These workers later found that fluorozincates and fluorosilicates give similar results 147). 

Ethynyl-ferf-butylmethylcarbinol allowed to react witb coned. HBr in tbe presence of a cuprous bromide-copper catalyst - l-bromo-3-ferf-butyl-3-metbylallene. Y 81-85%. F. e. s. D. K. Black et al., Tetrab. Let. 1963, 483. 

The reaction with ammonia or amines, which undoubtedly proceeds by the SNAr mechanism, is catalyzed by copper8" and nickel105 salts, though these are normally used only with rather unreactive halides.106 This reaction, with phase transfer catalysis, has been used to synthesize triarylamines.107 Copper ion catalysts (especially cuprous oxide or iodide) also permit the Gabriel synthesis (0-58) to be applied to aromatic substrates. Aryl bromides or iodides are refluxed with potassium phthalimide and Cu 0 or Cul in dimethylacetamide to give N-aryl phthalimides, which can be hydrolyzed to primary aryl amines.108... 

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