Crotonic acid anhydride

To evaluate the effects on biological activity of variations in structure of the ester moiety, several semisynthetic esters of maytansinol were prepared. The propionate (230), bromoacetate (231), crotonate (232), and trifluoroacetate (233) esters of maytansinol (229) were made by procedures involving either anhydride-pyridine (230-232) or anhydride-acid (233) treatment. Fig. (58). TTie esters 228, and 230-232 were found to show antileukemic activity comparable to those of the naturally occurring substituted alanyl esters. The trifluoroacetate ester 233 showed no antileukemic activity, possibly because of ready solvolysis in vivo to inactive maytansides. 

Crotonic anhydride, (CH3CH-=CHC0)20. Mol. wt. 154.16, b.p. 246-248. This reagent is prepared by treatment of crotonic acid with DCC in THF. 

CHa CHlCH CHO. Colourless lachrymatory liquid with a pungent odour. B.p. 104 "C. Manufactured by the thermal dehydration of aldol. May be oxidized to crotonic acid and reduced to crolonyl alcohol and 1-butanol oxidized by oxygen in the presence of VjOj to maleic anhydride. It is an intermediate in the production of l-butanol from ethanol. 

The hydiobiomides of /3-y unsaturated acids like /S-phenyl-crotonic acid beha e Cjuite differently. On l oiling with water, lactones are formed, i.e., inner anhydrides of o. y-acids,... 

The synthesis of key intermediate 12, in optically active form, commences with the resolution of racemic trans-2,3-epoxybutyric acid (27), a substance readily obtained by epoxidation of crotonic acid (26) (see Scheme 5). Treatment of racemic 27 with enantio-merically pure (S)-(-)-1 -a-napthylethylamine affords a 1 1 mixture of diastereomeric ammonium salts which can be resolved by recrystallization from absolute ethanol. Acidification of the resolved diastereomeric ammonium salts with methanesulfonic acid and extraction furnishes both epoxy acid enantiomers in eantiomerically pure form. Because the optical rotation and absolute configuration of one of the antipodes was known, the identity of enantiomerically pure epoxy acid, (+)-27, with the absolute configuration required for a synthesis of erythronolide B, could be confirmed. Sequential treatment of (+)-27 with ethyl chloroformate, excess sodium boro-hydride, and 2-methoxypropene with a trace of phosphorous oxychloride affords protected intermediate 28 in an overall yield of 76%. The action of ethyl chloroformate on carboxylic acid (+)-27 affords a mixed carbonic anhydride which is subsequently reduced by sodium borohydride to a primary alcohol. Protection of the primary hydroxyl group in the form of a mixed ketal is achieved easily with 2-methoxypropene and a catalytic amount of phosphorous oxychloride. 

DIHYDROFURAN DIVINYL ETHER METHACROLEIN 2-BUTYNE-1,4-DIOL ganna-BUTYROLACTONE cis-CROTONIC ACID trans-CROTONIC ACID METHACRYLIC ACID METHYL ACRYLATE VINYL ACETATE ACETIC ANHYDRIDE SUCCINIC ACID DIGLYCOLIC ACID MALIC ACID TARTARIC ACID n-BUTYRONITRILE ISOBUTYRONITRILE ACETONE CYANOHYDRIN... 

With the allylic intermediates, the introduction of oxygen is also possible and crotonaldehyde is one of the first oxygenated products to be formed. This molecule is not very stable, certainly not under reaction conditions, and will be further oxidized to crotonic acid or the relatively more stable furan. More severe oxidation will then result in the generation of maleic acid and its anhydride. 

SYNS ANHYDRIDKYSELINYKROTONOVE 2-BUTENOIC ACID, ANHYDRIDE (9CI) CROTONIC ACID ANHYDRIDE... 

A new acidic esterification has been reported in which a carboxylic silyl ester is condensed with an alcohol under the action of p-trifluoromethylbenzoic anhydride and a combination of HfCU and AgOTf as catalyst (Eq. 15). The esters are obtained in high yields even if almost equimolar amounts of substrates are employed. The method is applicable to the esterification of a,j8-enoic acids, such as crotonic acid, which is often hampered by side reactions, e.g. E Z isomerization, deconjugation, and the Michael reaction [21a,b]. 

Alfrey and Goldfinger (24) have shown that eqs. (7) cannot be employed if the system contains one or more components that cannot homopolymerize resp. add to a growing chain ending in a monomer unit of their own type, e.g. diethyl maleate, maleic anhydride, crotonic acid, sywm-dichlorethylene if monomer is of such type, and all the... 

An analogous methodology can be seen in the proposal to use chloroformamidinium salts as dehydrating agents. A A A /V -Tetramethylchloroformamidinium chloride, used as the condensation agent, is easily available by the reaction of A A A A -tetramethylurea and oxalyl dichloiide. The reaction of carboxylic acids (equation 33) can be achieved at -30 C in the presence of tiiethylamine. Thus, for instance, 2-furoic acid, cinnamic acid and crotonic acid yield e anhydrides in 84%, 83% and 83%, respectively. 

Oleic acid undergoes an interesting transformation when treated with a small quantity of nitrous anhydride. In a few minutes it is converted into a solid substance, which appears from its reactions to have a structure identical with that given above for oleic acid. The compound formed, called elaidic acid, is considered to be a stereoisomer of oleic acid, the relation between the two being similar to that between crotonic and... 

Poly(N-vinylpyrrolidone), P(NVP), is a nonionic, water-soluble polymer with high thermal and hydrolytic stability (7-9). Copolymers of N-vinylpyr-rolidone (NVP) with various carboxylate and carboxylate-precursor monomers (e.g., acrylic acid, sodium acrylate, crotonic acid, itaconic acid, and maleic anhydride) are also well-known (10). In addition, the homo- and copolymerization kinetics of these monomers are well-established. On the other hand, reports of copolymerizations of NVP with sulfonate monomers are sparse 11, 12). This chapter describes the synthesis, kinetics, and reactivity ratios for the copolymerization of NVP and some of the newer sulfonate monomers. A comparison of some of the solution properties for such copolymers is also included. 

Among the carboxylic acid and anhydride functional monomers that have been employed in the synthesis of these thickener polymers are acrylic acid, methacrylic acid, itaconic acid, citraconic acid, maleic acid, fumaric acid, crotonic acid, maleic anhydride, and citraconic anhydride. The copolymers containing maleic and citraconic anhydride monomers are either hydrolyzed or partially esterified to obtain the required carboxyl functionality. Among these carboxylic monomers, maleic anhydride and particularly methacrylic acid are most frequently favored. Carboxylic homopolymers, where they can be formed, might be considered the simplest examples of ASTs were it not for the fact that they are not copolymers as defined, and some are water soluble in their un-ionized states. Examples of carboxylic homopolymers are the un-ionized free-radical-polymerized atactic forms of polyacrylic acid (i) and polymethacrylic acid (2), which are both readily soluble in water. 

A. N. Dey (174) has described an independent synthesis of the alkaloids. Michael condensation of ethyl 7-ethoxy- or 7-phenoxy-crotonate (LI, R = OEt, R = Et or Ph) with ethyl malonate or cyan-acetate, followed by ethylation and hydrolysis, furnished a mixture of the two racemic forms of the glutaric acid, LII, which were separated by virtue of their different ease of anhydride formation. On treatment with hydrobromic acid, they gave rise to dl-homopilopic acid and dl-homo-isopilopic acid (LIII, R = OH), respectively. Corresponding methyl ketones (LIII, R = Me) were obtained by a similar synthesis from... 

Refluxing 4-(5-aryl-2-oxo-4-pyrrolinyl-3-idene)butyric acids with acetic anhydride gave the corresponding pyrrolo-3,4-dihydro-2-oxepinones, while similarly substituted crotonic acids gave pyr-rolo-2-oxepinones <87AKZ189>. 

Tallow Tallow alcohol Tosylamide/formaldehyde resin VA/crotonates copolymer Vinyl acetate/butyl acrylate copolymer Vinyl acetate/crotonic acid copolymer Vinylidene chloride/acrylonitrile copolymer Vinylidene chloride/methyl acrylate copolymer Vinylidene chloride/vinyl chloride copolymer Zinc laurate paper/paperboard, dry food-contact Acrylamides copolymer Acrylates copolymer Alkenyl succinic anhydride Ammonium maleic anhydride/diisobutylene copolymer Ammonium nitrate... 

---