These catalysts are respectively shown in FIGS. Specific catalysts are, for convenience, herein referred to by their molecular weights, some of which are the rounded off and shown below each structure in the figures.
They are also tabulated by FIG. Many of these catalysts are commercially available, but they are not generally thermally stable, and they generally cannot be used to synthesize trisubstituted olefins. Synthesis of Catalyst is described in U. Patent No. Catalyst is commercially available at a purity of greater than 95 percent from Boulder Scientific of Boulder, Colorado. Bis tricyclohexylphosphine dichloro ruthenium II 3-methyl-l,2-butadiene, Catalyst , and bis tricyclopentylphosphine dichloro ruthenium II 3-methyl-l,2- butadiene, Catalyst , are shown respectively in FIGS.
Catalysts and are commercially available from Strem of Newburyport, MA and are also preferred metathesis catalysts. Preferred Class II metathesis catalysts include, but are not limited to, Catalysts , , , , , and These catalysts are shown respectively in FIGS. These catalysts tends to be more thermally stable and more active than the Class I catalysts, but Class II catalysts are not commercially available or readily synthesized. In addition, the Class II catalysts cannot generally synthesize trisubstituted olefins.
Preferred Class III metathesis catalysts include, but are not limited to, Catalysts , , , , , , , , , , , and The Class III catalysts are not commercially available and are not readily synthesized. However, unlike Class I and Class II catalysts, Class III catalysts can be used to synthesize selected trisubstituted olefins, but cannot generally synthesize tetrasubstituted olefins. Preferred Class IV metathesis catalysts include, but are not limited to, Catalysts , , , , , , , , , , , and Reactions employing the Class IV catalysts generally need about 8 to 10 times less catalyst, particularly , compared to the amounts of Class I catalysts, particularly or , needed for the same reaction to obtain about the same yields.
Furthermore, the Class IV catalysts, particularly , complete a reaction in less than one hour while the Class I catalysts complete the same reaction in about 19 to 24 hours. Some of the Class IV catalysts specified above are or will be commercially available from Strem or can be synthesized as described by Scholl et al. The Class IV catalysts are especially preferred because they can be used to synthesize tetrasubstituted olefins as well as trisubstituted olefins.
Some of these catalysts of the formula where L'is it is selected from cycloalkyl, or alkyl-substituted cycloalkyl wherein the number of carbon atoms in the ring is from 4 to 12, or Cyclic NRw [ CHh Rt][ CHh Rv ] NRt C: wherein h is from 0 to 9 and Rw, Rs, Rt, and Rv are selected from hydrogen, aryl and alkyl, and where Rj and Rj have been described above.
This family of l,3-dimesityl-4,5-dihydro-imidazolylidene-substituted ruthenium-based complexes are preferred, such as Catalyst , shown in FIG. Catalysts , , and can be synthesized as described by Scholl et al Catalysts and are synthesized by adding two equivalents of ethyl vinyl ether to catalyst , stirring at room temperature for about three hours and isolating by precipitation.
Catalysts and have very interesting properties as they initiate the metathesis reactions in well defined temperature profiles. Other metathesis catalysts such as "well defined catalysts "could be alternatively be employed. Such catalysts include, but are not limited to, Schrock's molybdenum metathesis catalyst, 2,6-diisopropylphenylimido neophylidenemolybdenum VI bis hexafluoro-t-butoxide , described by Grubbs et al. Basset's catalyst is not presently commercially available, is sensitive to air, water, and a variety of functional groups, and is expensive to synthesize.
Other metathesis catalysts such as "non-well defined catalysts" could also be employed, but their activity depends on co-catalysts, which are typically heavy metals such as tetraalkyl tin or tetraalkyl lead compounds and present a waste disposal issue.
These non-well defined catalysts also require for activation the presence of strong Lewis acids, which may cause undesirable double bond migration. In Scheme A, two similar terminal olefins are self metathesized to yield an internal olefin. In Scheme B, an internal olefin is cross-metathesized with itself to yield two new internal olefins. In Scheme C, two dissimilar terminal olefins are cross metathesize to yield a new internal olefin.
In Scheme D, a terminal olefin and an internal olefin are cross metathesized to yield a new internal olefin. In Scheme E, two different internal olefins are cross metathesized to yield a new internal olefin. In Schemes F and G, the cross-metathesis products are hydrogenated under normal hydogenation conditions to yield corresponding saturated alkyl products. The following reactions, figures, and examples are shown herein only by way of example to the above-described type of metathesis syntheses and should not be considered as limiting the scope of the invention.
In particular, FIG. The reaction favors 5-decene formation because ethylene is removed from the reaction as it is formed. Running the reaction under vacuum removes 1-hexene and results in high conversions of 5-hexenyl acetate to 5-decenyl acetate and an trans: cis ratio of isomeric products. The following examples demonstrate the preparation of the PTB pheromone, but should not be regarded as a limitations to the scope of the invention.
The flask was sparged with nitrogen for 10 minutes. Catalyst 2. The evolution of ethylene gas from the reaction was observed. The spent catalyst was removed by filtering the reaction through g of J.
Baker Silica Gel mesh in a 1. The solvent and unreacted 1-hexene were removed under reduced pressure to yield g 0. This product was used in the next reaction without further purification. The flask was sparged with nitrogen for 5 minutes, Catalyst 1. After 16 hours, the vacuum pump was removed and the reaction was stirred for an additional 12 hours under a nitrogen atmosphere.
GC analysis indicated 87 percent 5-decenyl acetate, 12 percent l,diacetoxydecene, and less than one percent 5-hexenyl acetate. A purified sample of 5-decenyl acetate was obtained by filtering about half of the reaction mixture through g of J. Baker silica gel in a 1. The column was rinsed with 1 L of petroleum ether, followed by rinsing with 1 L of 10 percent diethyl ether in petroleum ether.
Two hundred-milliliter fractions were collected. The data are summarized below. GC Results Fraction Number 5-decene 5-decenyl acetate 1, diacetoxydecene 1 0 0 0 2 0 0 3 91 9 0 4 0 0 5 0 0. Das, Siddhartha Ghosh and Arthur F. Chemistry of Materials , 21 23 , Chemistry of Materials , 0 proofing DOI: Journal of the American Chemical Society , 42 , David J.
Michaelis, Michael A. Ischay and Tehshik P. Journal of the American Chemical Society , 20 , The Journal of Organic Chemistry , 73 8 , Stuart G. Leach,, Christopher J. Cordier,, Daniel Morton,, Gordon J.
The Journal of Organic Chemistry , 73 7 , Hrib,, Peter G. Jones, and, Matthias Tamm. Organic Letters , 10 5 , Olivier Debleds and, Jean-Marc Campagne. Journal of the American Chemical Society , 5 , Organometallics , 26 22 , Zhuqing Liu and, Jon D. An Entry into Perhydroindolines. Organic Letters , 8 3 , Organic Letters , 7 7 , Julia-Christina Wasilke,, Stephen J. Obrey,, R. Tom Baker, and, Guillermo C. Concurrent Tandem Catalysis.
Chemical Reviews , 3 , Shown below are some of these catalysts, which tolerate more functional groups and are more stable and easy to handle. The Schrock catalysts are more active and are useful in the conversion of sterically demanding substrates, while the Grubbs catalysts tolerate a wide variety of functional groups.
The second generation Grubbs catalysts are even more stable and more active than the original versions.
Some of these are depicted: K.Santiago, Christopher P. Market visit report ppt Michaelis, Basil A. References 1. Dennis G. Of these, the Grubbs ruthenium-based offerings have been particularly successful. Older, Peng Liu, Tara Y. Otieno et al. Remote image in new window Fig. The naughty time of 18 to 25 never does not include the educational for the final distillation.
When precisely spaced alkyl groups are placed every 7th carbon or closer, the resulting polymers are amorphous.
Osgood, C. Ethylene copolymers The advent of ADMET polymerization not only promoted modeling of polyethylene, but also stimulated the understanding of numerous classes of polymers. The flask was sparged with nitrogen for 10 minutes.
Jason K. In a general embodiment, R is selected from hydrogen, alkyl, aryl, or derivatives thereof. Although the 20 percent cisdecenyl acetate does not affect the efficacy of the PTB pheromone in lures and mating disruption applications, the low yield and the long completion time make the process expensive. Olivier Debleds and, Jean-Marc Campagne. Preferred syntheses of mosquito oviposition attractant pheromone involve the cross-metathesis of commercially available materials, such as meadowfoam oil, hexenoic acid derivatives, hexenal derivatives, or hexenol derivatives with 1-dodecene or docosene, followed by oxidation of the double bond and lactonization. Andreana,, Daesung Lee, and, Stuart L.
Various copolymers of ethylene and polar vinyl intermediates were scrutinized and compared to commercial samples.
In a general embodiment, g, k, m, and n are each selected from zero and an integer less than or equal to Ahmed, Chen Xu, Brian M. Precision alkyl-branched polyethylenes were found to possess enhanced thermal properties due to higher crystallinity, leading to sharper melting transitions at lower temperatures and greater heats of fusion.
However, perfectly linear ethylene—vinyl acetate copolymers can be prepared by means of ADMET polymerization [ 56 ]. Louis encephalitis virus and other arboviruses in the United States. On the other hand, Grubbs did not rule out the possibility of a tetramethylene intermediate. The Journal of Organic Chemistry , 73 8 ,
Investigation of a degenerate olefin metathesis reaction.
Despite the presence of the three inactive and unnatural stereoisomers of 5, 6 acetoxyhexadecanolide [ i. The reaction favors 5-decene formation because ethylene is removed from the reaction as it is formed. In Scheme E, two different internal olefins are cross metathesized to yield a new internal olefin.
The introduction of branches leads to less-ordered crystalline structures, of which there are several examples in the literature [ 47 , 48 ]. By varying the size and interval of alkyl branches on polyethylene, the resulting morphological effects are delineated. In a preferred embodiment, the improvements include: 1 a technique to obtain higher conversion of starting materials to products from 40 percent to greater than 75 percent ; 2 an increase in the metathesis transxis ratio from to between to 16; 3 only two reaction steps; and 4 a production time of less than a week.
If these side products are volatile, they can easily be removed under vacuum pressure or under high temperature. In a general embodiment, R is selected from hydrogen, alkyl, aryl, or derivatives thereof. The significant insolubility of the poly ethylene-co-vinylsulfonic acid s promotes premature precipitation of the material and prevents complete deprotection. The same ratio is found with the higher oligomers.