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2- oxetanone, 4-Methylene

DimeriZa.tlon. A special case of the [2 + 2] cyclo additions is the dimerization of ketenes. Of the six possible isomeric stmctures, only the 1,3-cyclobutanediones and the 2-oxetanones (P-lactones) are usually formed. Ketene itself gives predominandy (80—90%) the lactone dimer, 4-methylene-2-oxetanone (3), called diketene [674-82-8], approximately 5% is converted to the symmetrical dimer, 1,3-cyclobutanedione [15506-53-3] (4) which undergoes enol-acetylation to so-called triketene [38425-52-4] (5) (44). [Pg.474]

Methylene-2-oxetanone, or diketene (37), does not decarboxylate on heating but cleaves to form ketene at 250 °C. A thermal rearrangement of 3-aryl-4-benzal-2-oxetanones (38) to form naphthalene derivatives appears to involve this type of pyrolysis, followed by a [ 2 + 4] cycloaddition (78JOC1146, 72LA(765)15>. [Pg.374]

A similar type of acid-catalyzed condensation of aldehydes with 4-methylene-2-oxetanone (diketene), giving 4-oxo-6-methyl-l,3-dioxins, has been patented (73GEP2149650). However, other work has established that <5-hydroxy-/3-keto acids or unsaturated keto acids are formed as the principal products (equation 24) (78CPB3877, 78CL409). The latter reaction probably involves electrophilic attack of the protonated aldehyde on the nucleophilic exocyclic methylene carbon atom of the diketone. A closely related reaction of acetals with diketene, catalyzed by titanium tetrachloride, gives the corresponding <5-alkoxy-/3-keto esters (74CL1189). [Pg.380]

Ketene dimerization is the principal synthetic route to 4-methylene-2-oxetanones. This reaction proceeds very satisfactorily for ketene and methylketene, but disubstituted ketenes dimerize only to cyclobutane-1,3-diones. The cycloaddition reaction of r-butylcyanoketene to ketene and to methylketene gives a-cyanoalkylidene-/3-lactones in about 40% yield in addition to the cyclobutane-1,3-dione dimer of f-butylcyanoketene. A mechanism has been proposed for the formation of both types of dimers from a common zwitterionic intermediate (equation 111), with the relative amount of each product determined by the configurational equilibrium of the intermediate (80JOC4483, 75JOC3417). [Pg.398]

Methylenemagnesium, 0401 f 4-Methylene-2-oxetanone, see Diketene, 1437 f Methyl ethanoate, see Methyl acetate, 1228... [Pg.2111]

The theoretical infrared (IR) spectra of diketene 4-methylene-2-oxetanone isomers (e.g., 2) and mono- and disulfur analogues such as 3 have been calculated at the MP2/6-311+- -G level to provide data on whether new analogues could potentially be prepared <2001JST433>. [Pg.323]

The chemistry of methylene-substituted 2-oxetanones, and in particular diketene, has attracted a vast amount of research over the years, so other alkylene-substituted oxetanes and oxetan-2-ones, including methylene oxetanes, are discussed separately in Section 2.05.7.4. Diketene is also known as 4-methylene-2-oxetanone and a notable difference between this and other 2-oxetanones is that it undergoes thermal decomposition by a cycloreversion reaction to give ketene, rather than forming allene and C02. CHEC-II(1996) refers to a series of comprehensive reviews of the chemistry of this compound <1996CHEC-II(1)721>. [Pg.338]

SYNS 3-BUTENO-p-LACTONE DIKETENE DIKETENE, inhibited (DOT) 4-METHYLENE-2-OXETANONE... [Pg.813]

METHYLENE-2-OXETANONE see KFAOOO METHYLENE OXIDE see FWOOO S,S -METHYLENE 0,0,0, 0 -TETRAETHYL PHOSPHORODITHIOATE see EEH600 8-METHYLENE-4,ll,ll-... [Pg.1773]

METHYLENE-2-OXETANONE (674-82-8) Forms explosive mixture with air (flash point 91°F/33 C). A strong reducing agent. Violent reaction with water, strong oxidizers. [Pg.779]

Beilstein Handbook Reference) Acetyl ketene BRN 0104541 But-3-en-3-olide 3-Buteno-p-lactone 3-Butenoic acid, 3-hydroxy-, p-lactone Diketene EINECS 211-617-1 Ethenone, dimer HSDB 2063 Ketene, dimer 4-Methylene-2-oxetanone NSC 93783 2-Oxetanone, 4-methylene- UN2521 Vinyl-aceto-p-lactone. Liquid mp = -6.5 bp = 126.1 d = 1.0877. [Pg.222]


See other pages where 2- oxetanone, 4-Methylene is mentioned: [Pg.491]    [Pg.626]    [Pg.379]    [Pg.379]    [Pg.562]    [Pg.491]    [Pg.379]    [Pg.491]    [Pg.2029]    [Pg.702]    [Pg.779]    [Pg.244]    [Pg.703]   
See also in sourсe #XX -- [ Pg.256 ]




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2-oxetanone

Diketene: 2-Oxetanone, 4-methylene

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