Crotonate compounds

Maleate Surfmers were found to outperform methacrylic and crotonic compounds in the copolymerization of styrene, butyl acrylate and acrylic acid in seeded and nonseeded semicontinuous processes [17]. The maleate Surfmer achieved high conversion without homopolymerization in the aqueous phase which can result in emulsion instability. The methacrylate Surfmer was too reactive as opposed to the crotonate which was not sufficiently reactive. The reported dependence of the maleate Surfmer conversion on the particle diameter is consistent with a reaction at the particle surface. 

Recently, this kind of surfmer was studied in more detail [43] in the copolymerization of styrene, butylacrylate, and acrylic acid (49 49 2) in semi-continuous (seeded or nonseeded) protocols at 30% or 50% solid contents recipes, on the basis of kinetics (both overall and instantaneous whole conversion), evaluation of the surface tension, and amount of coagulum produced. The reactivity ratios with the comonomer have also been measured for the reaction that took place in water phase, and a two-phase titration technique has been developed to analyze the conversion of the surfmers. The behavior of these surfactants was compared to that of a methacrylic compound and a crotonic compounds (IX and X of Table 3). 

Karathane A trade name for 2,4-dinitro-6-( 1 -methylheptyl)phenyl crotonate, CJ8H24N2O6, a compound which has both acaricidal and fungicidal activity. It is a red-brown oil of high boiling point, insoluble in water but soluble in most organic solvents. Karathane is used for the control of powdery mildew, and is nontoxic to mammals. 

The carbonylation of some alkyl halides such as iodocyclohexane (911) can be carried out under neutral conditions in the presence of N,N,N.N-tetre,-methylurea (TMU), which is a neutral compound, but catches generated hydrogen halide. Molecular sieves (MS-4A) are used for the same pur-pose[768]. Very reactive ethyl 3-iodobutyrate (912) is carbonylated to give ethyl methylsuccinate (913) in the presence of TMU. The expected elimination of HI to form crotonate, followed by carbonylation, does not occur. 

A number of activated olefinic compounds react very weU in this scheme including methacrylates, crotonates, acrylonitrile, and vinyl ketones. These reactions are typicaHy mn in an etherial solvent and can be mn without the complications of undesirable side reactions leading to trialkylated tin species. 

Primary fatty amines also add (Michael addition) to esters of acryUc acid, H2C=CHCOOH, methacrylic acid, H2C=C(CH2)COOH, or crotonic acid, CH2CH=CHC00H. Hydrolysis of the Michael ester forms an amphoteric surfactant. Crotonic acid can be used to form the amphoteric compound... 

Chemically, wood tar is a complex mixture that contains at least 200 individual compounds, among which the foUowing have been isolated (1) 2-methoxyphenol, 2-methoxy-4-ethylphenol, 5-meth5i-2-methoxyphenol, 2,6-x5ienol, butyric acid, crotonic acid, 1-hydroxy-2-propanone, butyrolactone, 2-methyl-3-hydroxy-4JT-pyran-4-one, 2-methyl-2-propenal, methyl ethyl ketone, methyl isopropyl ketone, methyl furyl ketone, and 2-hydroxy-3-methyl-2-cyclopenten-l-one. 

Cyclic g-haloacetals and -ketals have been prepared by variations on two basic methods. The most frequently used method involves the combination of an a,B-unsaturated carbonyl compound (acrolein, methyl vinyl ketone, croton-aldehyde, etc.) a diol, and the anhydrous hydrogen halide. All possible sequences of combining these three have been used. In most cases the... 

More serious limitations and precautions apply to compounds in which not all three R, R, and R" groups are aromatic. Autocondensation of benzylideneacetone (111) yields an unstable chloroferrate which may be 113 or 115, according to whether a Michael addition to 112 or a crotonic condensation to 114 is first involved. Since compound 113 could readily be prepared from 2,6-dimethyl-4-phenylpyrylium and benzaldehyde, the structure of the reaction product should be easily soluble. Another equivocal product is formed from two moles of benzylideneacetone, but a definite structure (116) results from chalcone and benzylideneacetone. ... 

Michael addition reaction of 1-hydroxytryptamines to Q ,/3-unsaturated carbonyl compounds is worthy of note (99H2815). Addition of Ab-acetyl- 1-hydroxy-tryptamine (39) to methyl acrylate and methyl crotonate in the presence of... 

The propensity for polymerisation is given by codes 1 or 2 of the NFPA reactivity code. The risk related to polymerisation is given in the transport regulations of dangerous compounds. The table below gives the available data. Crotonic acid is added, which has a surprising low NFPA code. 

Aliphatic compounds Several water-soluble simple organic acids and alcohols are cannon plant and soil constituents. They include methanol, ethanol, n-propanol and butanol (40), and crotonic, oxalic, formic, butyric, lactic, acetic and succinic acids (41, 42), all of which inhibit seed germination or plant growth. Under aerobic conditions, however, aliphalic acids are metabolized in the soil and therefore, should not be considered a major source of allelopathic activity (40). 

Poly(vinyl alcohol) has the structure 10.67. Poly(vinyl acetate) is the fully esterified derivative of polyfvinyl alcohol), in which the -OH groups are replaced by -OCOCH3 groups. As indicated in Table 10.5, commercial polyvinyl sizes are effectively copolymers of polyfvinyl acetate) and polyfvinyl alcohol) that vary in the degree of saponification of the ester groups. These products may comprise 100% of either polymer, or combinations of the two monomers in any proportions. Crotonic acid (2-butenoic acid), widely used in the preparation of resins, may also be a component. This compound exhibits cis-trans isomerism (Scheme 10.17). The solid trans form is produced readily by catalysed rearrangement of the liquid cis isomer. 

Herein, the stereogenic center in 2-12 controls the stereochemistry in the way that the Michael addition occurs from the less-hindered a-face of the enolate to the si-side of the crotonate 2-13 according to transition structure 2-16. The second Michael addition occurs from the same face, again under chelation control, followed by an axial protonahon of the formed enolate to give the cis-compound 2-14a. It should be noted that after the usual aqueous work-up procedure an inseparable... 

Palladium(II) acetate was found to be a good catalyst for such cyclopropanations with ethyl diazoacetate (Scheme 19) by analogy with the same transformation using diazomethane (see Sect. 2.1). The best yields were obtained with monosubstituted alkenes such as acrylic esters and methyl vinyl ketone (64-85 %), whereas they dropped to 10-30% for a,p-unsaturated carbonyl compounds bearing alkyl groups in a- or p-position such as ethyl crotonate, isophorone and methyl methacrylate 141). In none of these reactions was formation of carbene dimers observed. 7>ms-benzalaceto-phenone was cyclopropanated stereospecifically in about 50% yield PdCl2 and palladium(II) acetylacetonate were less efficient catalysts 34 >. Diazoketones may be used instead of diazoesters, as the cyclopropanation of acrylonitrile by diazoacenaph-thenone/Pd(OAc)2 (75 % yield) shows142). 

The Michael-type reaction of an anion (generated from compound 77) with ethyl crotonate yielded the corresponding ester 78 in 82% yield (Scheme 19). Alkylation of compound 77 with benzyl bromide afforded derivative 79 in 85% yield. The attempted reactions of the anion with oxiranes and trimethylsilyl chloride did not lead to the expected substitution products and the starting oxadiazoles were recovered in 70-80% yields <2001ARK101>. 

Mironov et al. (26) also tried to cyclize acyloxysilanes with some success in making a series of silalactones. They used the series HMe2SiOOC(CH2) CH=CH2 (n = 0, 1, 2, 8). When n = 0, vinylpoly-merization of the acrylate occurred. This was also true for crotonic, cinnamic, and methacrylic esters to complicate and confuse the experiments, but with n = 1, 2, or 8, the compounds reacted readily. 

The absolute stereochemistry for 150 (entries 2 and 3) was determined by hydrolysis and conversion to known compounds. Assuming a tetrahedral or cis octahedral geometry for the magnesium [110], the product stereochemistry is consistent with si face radical addition to an s-cis conformer of the substrate. This is the same sense of selectivity as that obtained with oxazo-lidinone crotonates or cinnamates suggesting that the rotamer geometry of the differentially substituted enoates is the same. The need for stoichiometric amount of the chiral Lewis acid to obtain high selectivity with 148 in contrast to successful catalytic reactions with crotonates is most likely a reflection of the additional donor atom present in the substrate. 

NDGA also inhibits 5-LO in a variety of systems [65-68]. In vivo, antiinflammatory activity has been reported in lipopolysaccharide (LPS)-in-duced knee inflammation in rats [69] and in AAE and croton oil induced ear oedema [70,71]. However, in a 14-day clinical trial in psoriasis, no efficacy was seen following topical application of NDGA [72]. Although this compound has been used as an archetypal 5-LO inhibitor in many studies, the general antioxidant properties of this compound require caution in these interpretations. 

Another problem for the synthetic use of PFR is that the ortho-rearranged products may act as internal light filters, stopping the reaction. In synthetic routes leading to chromanones, chromones, and related compounds, this is of vital importance because the overall yield is limited by the photochemical step. Improved yields can be obtained if the a, 3-unsamrated orr/io-hydroxyphenones resulting from PFR are removed and cyclized to chromanones. This can be acomplished in one pot by irradiation in a two-phase system benzene/10% aqueous NaOH, whereby chromanones are directly obtained from phenyl crotonates in 80-90% yields [210]. 

Among the dihydro analogues of thiouracil, 2-mercapto-6-methyl-5,6-dihydro-uracil (LXXX) retains some of the antithyroid activity exhibited by 2-thiouracils [642] (see Part 1 of this review. Volume 6). This compound can be obtained either by the condensation of thiourea with ethyl crotonate or by the hydrogenation of 2-mercapto-6-methyluracil. 

The same authors (77) also investigated the Michael addition of nitromethane to a,/l-unsaturated carbonyl compounds such as methyl crotonate, 3-buten-2-one, 2-cyclohexen-l-one, and crotonaldehyde in the presence of various solid base catalysts (alumina-supported potassium fluoride and hydroxide, alkaline earth metal oxides, and lanthanum oxide). The reactions were carried out at 273 or 323 K the results show that SrO, BaO, and La203 exhibited practically no activity for any Michael additions, whereas MgO and CaO exhibited no activity for the reaction of methyl crotonate and 3-buten-2-one, but low activities for 2-cyclohexen-l-one and crotonaldehyde. The most active catalysts were KF/alumina and KOH/alumina for all of the Michael additions tested. 

The benzenic extract from leaves of Croton pyramidalis was highly inhibitory. From this extract we isolated a flavone and a diterpene (Figure 1) but there are other compounds not yet identified in this extract that are much more toxic (11). 

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