Copolymerization Behavior of β-Angelica Lactone and Styrene in the Presence of Organoaluminum Chlorides

Abstract

In order to synthesize polymers containing lactone units in the backbone chains and use them as membranes, copolymerization of /3-angelica lactone (/3-AL) with styrene was carried out. Using 0(,0('-azobisisobutyronitrile at 60°C, /3-AL did not copolymerize readily. In the presence of ethylaluminum sesquichloride or diethylaluminum chloride as a complexing reagent in toluene at 20°C, however, /3-AL copolymerized much more readily. Spontaneous initiation took place and a copolymer containing about 50 mol% of /3-AL units was obtained under the most favorable conditions. Nevertheless, it seemed unlikely that regular, highly alternating sequences could be achieved in this manner, in contrast to the well-known Lewis acid-complexed copolymerization of acrylic esters and styrene. NMR studies demonstrated that, while the binary complex between /3-AL and ethylaluminum sesquichloride was formed almost instantly and completely, the ternary complex between styrene, /3-AL and ethylaluminum sesquichloride had a rather low stability constant (,;:; 0.05 dm 3 mol-1) which accounts for the imperfectly alternating sequences.

Lignocellulosic biomass: a sustainable platform for the production of bio-based chemicals and polymers

“…They carried out radical copolymerization of β-ANL with styrene in order to obtain polymers containing lactone units in the backbone chains. 347 2-Butanone (methyl ethyl ketone, MEK) (Fig. 23) is commonly used as an industrial solvent.…”

Angelica Lactones: From Biomass‐Derived Platform Chemicals to Value‐Added Products

“…In this context, Hirabayashia nd Yokota have investigated the use of organoaluminum chlorides for the preparation of a b-AL-styrene copolymer. [38] Although aperfectly alternating copolymerc ould not be achieved, copolymers containing moderate amountso fl actone units in their structure have been obtained. The presenceo faLewis acid is crucial for achieving the alternating copolymerization product (Scheme 16).…”

Production and Polymerization of Biobased Acrylates and Analogs

“…Dehydration of levulinic acid leads to a mixture of α‐angelica lactone (α‐AL) and β‐AL that can be isolated prior to further hydrogenation to GVL ( Figure ). [ 204 ] The isomerization of α‐AL to β‐AL is catalyzed under acidic [ 204 ] or basic [ 205 ] conditions with moderate heating, facilitated by the conjugation of the double bond in β‐AL. Enantioselective isomerization has also been reported, [ 206 ] although the polymerization of the chiral monomer has never been described.…”

“…In 1982, Hirabayashi and Yokota described the free radical copolymerization of β‐AL with styrene (a reactive, electron‐rich comonomer). [ 205 ] This reaction, however, required the stoichiometric addition of aluminum chloride complexes to successfully incorporate β‐AL. The copolymer was not perfectly alternated, although it is expected when copolymerizing polar electron‐rich and electron‐poor comonomers.…”