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The alkenyl succinic anhydrides are prepared with an excess of isoalkene at temperatures >200 °C under nitrogen atmosphere for more than 3 hours; the excess iso-alkene is distilled off at reduced pressure. Synthesis of ASA from maleic anhydride and alkene.
Succinic anhydride hydrolyzes readily to give succinic acid: (CH 2 CO) 2 O + H 2 O → (CH 2 CO 2 H) 2. With alcohols (ROH), a similar reaction occurs, delivering the monoester: (CH 2 CO) 2 O + ROH → RO 2 CCH 2 CH 2 CO 2 H. Succinic anhydride is used in acylations under Friedel-Crafts conditions, as illustrated by the industrial route to the ...
Starch is the most common sizing agent. Cationic starch and hydrophilic agents are also applied, including alkenyl succinic anhydride (ASA) and alkyl ketene dimers (AKD). [5] Cationic starch increases strength because it binds to the anionic paper fibers. [6] The amount added is usually between ten and thirty pounds per ton.
At several places AKD (alkyl ketene dimer) and ASA (alkenyl succinic anhydride) are used. Latest development is to use surface size, [5] which is applied using a size press. The advantage of surface sizing is that it does not interfere with the backend water chemistry.
In chemistry, 3,3,4,4-tetramethyltetrahydrofuran-2,5-dione is a heterocyclic compound with the formula C 8 H 12 O 3, or (CH 3) 2 (COC 2 COO)(CH 3) 2.It is a white crystalline solid with a pungent camphoraceous odor.
Anhydrides experience even weaker resonance stabilization, since the resonance is split between two carbonyl groups, and are more reactive than esters and amides. In acid halides, there is very little resonance, so the energetic penalty for forming a tetrahedral intermediate is small.
In 1901, Edgar Wedekind published the synthesis of alkyl ketene dimers by the reaction of carboxylic acid chlorides with tertiary amines: [5] [6] RCH 2 COCl + R 3 N → RCH=C=O + R 3 NHCl The molecular weight determined by the early researchers indicated (CH 3) 2 CH=C=O) n where n > 1 for the dehydrohalogenation of isobutyryl chloride with triethylamine.
Isopropyl group Methyl group. In organic chemistry, an alkyl group is an alkane missing one hydrogen. [1] The term alkyl is intentionally unspecific to include many possible substitutions.