Acetal Metathesis: Mechanistic Insight

Alexander G. Pemba; Stephen A. Miller

doi:10.1055/s-0037-1611833

Synlett, Inhaltsverzeichnis

Synlett 2019; 30(17): 1971-1976
DOI: 10.1055/s-0037-1611833

cluster

Acetal Metathesis: Mechanistic Insight

Alexander G. Pemba

,

Stephen A. Miller *

The George and Josephine Butler Laboratory for Polymer Research, Department of Chemistry, 165 Buckman Drive, University of Florida, Gainesville, FL, 32611-7200, USA eMail: miller@chem.ufl.edu

› Institutsangaben

Abstract

Alle Artikel dieser Rubrik

Published as part of the Cluster Metathesis beyond Olefins

Abstract

The origins and recent applications of acetal metathesis are discussed in the context of synthesizing polyacetals via acetal metathesis polymerization (AMP). A kinetic study of the acid-catalyzed acetal metathesis reaction suggests the rate = k[H⁺][acetal]², with MeOCH₂OMe and EtOCH₂OEt interchanging to yield MeOCH₂OEt, achieving the statistical 1:2:1 equilibrium distribution in 4 hours at 80 °C and in 1 hour at 90 °C. Upon heating 1,10-decanediol and diethoxymethane, polydecylene acetal is formed with sequential distillation of ethanol, followed by diethoxymethane. A full mechanism for this polymerization is proposed, which begins with a transacetalization sequence to convert the diol into a bisacetal, followed by acetal metathesis to yield a high-molecular-weight polymer.

Key words

acetal - metathesis - transacetalization - polyacetal - acid catalysis - kinetic study - nucleophilicity

Volltext

Referenzen

References and Notes
1 Currently at: Intel Corporation, Ronler Acres Campus, 2501 NE Century Blvd., Hillsboro, OR 97124, USA.
2 Handbook of Olefin Metathesis, 2nd ed. Grubbs RH, Wenzel AG. Wiley-VCH; Weinheim: 2015
3 Google: https://www.google.com (accessed Jan 14, 2019).
4 IUPAC Gold Book, metathesis. https://goldbook.iupac.org/ html/M/M03878.html (accessed April 25, 2019).
5 Miller SA, Pemba AG. US Patent 9217058, 2015
6 Pemba AG, Flores JA, Miller SA. Green Chem. 2013; 15: 325

7a Chikkali S, Stempfle F, Mecking S. Macromol. Rapid Commun. 2012; 33: 1126
7b Rajput BS, Chander U, Arole K, Stempfle F, Menon S, Mecking S, Chikkali SH. Macromol. Chem. Phys. 2016; 217: 1396
7c Hufendiek A, Lingier S, Du Prez FE. Polym. Chem. 2019; 10: 9
7d Nguyen HT. H, Qi P, Rostagno M, Feteha A, Miller SA. J. Mater. Chem. A 2018; 6: 9298

8 Sahmetlioglu E, Nguyen HT. H, Nsengiyumva O, Göktürk E, Miller SA. ACS Macro Lett. 2016; 5: 466
9 Vanderhenst R, Miller SA. Green Mater. 2013; 1: 64
10 Garcia JJ, Miller SA. Polym. Chem. 2014; 5: 955
11 Miller SA. ACS Macro Lett. 2013; 2: 550

12a Coleman CG. Dissertation 1991
12b McInnes JM, Mountford P. Chem. Commun. 1998; 1669
12c Lee YH, Morandi B. Nat. Chem. 2018; 10: 1016

13a Hill JW, Carothers WH. J. Am. Chem. Soc. 1932; 54: 1569
13b Hill JW, Carothers WH. J. Am. Chem. Soc. 1933; 55: 5031

14 Hill JW, Carothers WH. J. Am. Chem. Soc. 1935; 57: 925

15a Bielawski CW, Grubbs RH. Prog. Polym. Sci. 2007; 32: 1
15b Trnka TM, Grubbs RH. Acc. Chem. Res. 2001; 34: 18
15c Grubbs RH. Tetrahedron 2004; 60: 7117
15d Schrock RR. Chim. Oggi 2009; 27: 2

16 Opper KL, Wagener KB. J. Polym. Sci., Part A: Polym. Chem. 2011; 49: 821

17a Gazizova LB, Imashev UB, Musavirov RS, Kantor EA, Zlotskii SS, Kuz’michev AA, Rakhmankulov DL. J. Org. Chem. USSR (Engl. Transl.) 1981; 17: 226
17b Schaper U.-A. Synthesis 1981; 794

18 Protocol for ¹H NMR Analysis of Acetal Metathesis between MeOCH₂OMe and EtOCH₂OEtAn equimolar stock solution was prepared containing 0.5000 mol (38.05 g) of MeOCH₂OMe and 0.5000 mol (52.08 g) of EtOCH₂OEt. Then, 0.20 mL of this stock solution was added to a J. Young NMR tube, followed by 0.8 mL of toluene-d ₈, and 1.9 mg (0.011 mmol) of p-TSA (0.5 mol%). The sample was equilibrated at 80 °C (or 90 °C) for 10 minutes before acquiring ¹H NMR spectra every 5 minutes for 345 (or 360) minutes. The acetal proton peaks at 4.49 ppm (EtOCH ₂OEt), 4.56 ppm (MeOCH ₂OEt), and 4.63 ppm (MeOCH ₂OMe) were automatically integrated for each spectrum.
19 Additional details for the distillate collection and analysis are found in the Supporting Information.
20 Čorić I, Vellalath S, List B. J. Am. Chem. Soc. 2010; 132: 8536
21 McIntyre D, Long FA. J. Am. Chem. Soc. 1954; 76: 3240
22 The pK _a values of protonated dimethoxymethane and protonated diethoxyethane have been indirectly measured to be –4.87 and –4.43, respectively. See: Kankaanperä A. Acta. Chem. Scand. 1969; 23: 1723
23 Wolford RK. J. Phys. Chem. 1964; 68: 3392
24 Trioxane is commonly proposed to be a nucleophile during its polymerization. See: Weissermel K, Fischer E, Gutweiler K, Hermann HD, Cherdron H. Angew. Chem., Int. Ed. Engl. 1967; 6: 526
25 Jaramillo P, Pérez P, Contreras R, Tiznado W, Fuentealba P. J. Phys. Chem. A 2006; 110: 8181
26 Moore JW, Pearson RG. Kinetics and Mechanism: A Study of Homogeneous Chemical Reactions, 3rd ed. John Wiley & Sons; New York: 1981: 16
27 Jones CM, Lewis WC. M. J. Chem. Soc., Trans. 1920; 117: 1120
28 Protocol for the Bisacetal SynthesisA 1 liter round-bottom flask was charged with 17.43 g (0.100 mol, 1 equiv) of 1,10-decanediol, 208.30 g (2.00 mol, 20 equiv) of diethoxymethane, 0.190 g (1 mol%) of para-toluenesulfonic acid, and 100 mL of toluene. Ethanol was exhaustively removed via distillation over 24 h, followed by refluxing for 48 h. Workup, as described in the Supporting Information, afforded the bisacetal as a colorless oil in 72% yield (21.03 g).

Zusatzmaterial

Supporting Information