Method of making a dialdeyhde

Description

FIELD OF THE INVENTION

This application relates to chemistry generally. In particular, this application relates to a novel method of making dialdehydes from diepoxides.

BACKGROUND OF THE INVENTION

Mono-epoxide to mono-aldehyde rearrangements are well known in the chemical arts. However, di-epoxide rearrangement to di-aldehyde processes are less known. For example, common Lewis acids and Bronsted acids lead to oligomerization and the production of complex mixtures of products when a difunctional rearrangement is attempted.

Di-aldehydes are particularly useful as chemical intermediates to make material such as enol ethers. It would be desirable to have an efficient process to make dialdehydes from diepoxides. The invention disclosed herein describes a two-step process to make a dialdehyde wherein a diepoxide is first hydrolyzed with an alcohol solvent to an intermediate which is then subjected to a double-Pinacol rearrangement to obtain a dialdehyde.

SUMMARY OF THE INVENTION

The Invention is set forth in the appended claims.

In an embodiment this invention comprises a method for making dialdehydes from diepoxides comprising:

• • a) combining an alcohol with a diepoxide in the presence of a base to form a first mixture;
  • b) heating said first mixture to form a second mixture;
  • c) adding an acid to the second mixture to form a third mixture; and
  • d) separating dialdehyde from the third mixture.

DETAILED DESCRIPTION

Definitions

In this specification and in the claims that follow, reference will be made to a number of terms, which shall be defined to have the following meanings.

“Alcohol” means a chemical containing one or more hydroxyl groups.

“Aldehyde” means a chemical containing one or more —C(O)H groups.

As used herein, the terms “a,” “an,” and “the” mean one or more.

As used herein, the term “and/or,” when used in a list of two or more items, means that any one of the listed items can be employed by itself or any combination of two or more of the listed items can be employed. For example, if a composition is described as containing components A, B, and/or C, the composition can contain A alone; B alone; C alone; A and B in combination; A and C in combination, B and C in combination; or A, B, and C in combination.

As used herein, the terms “comprising,” “comprises,” and “comprise” are open-ended transition terms used to transition from a subject recited before the term to one or more elements recited after the term, where the element or elements listed after the transition term are not necessarily the only elements that make up the subject.

As used herein, the terms “having,” “has,” and “have” have the same open-ended meaning as “comprising,” “comprises,” and “comprise” provided above.

As used herein, the terms “including,” “includes,” and “include” have the same open-ended meaning as “comprising,” “comprises,” and “comprise” provided above.

Presented herein is a process to directly convert a diepoxide to a dialdehyde via a novel synthesis method.

Mono-epoxide to mono-aldehyde rearrangements are well known. However, when attempting to extend scope to di-aldehyde to di-epoxide rearrangement, there are few chemistry options. For example, common Lewis acids and Bronsted acids lead to oligomerization and the production of complex mixtures of products when a difunctional rearrangement is attempted. The inventors tested tritylium tetrafluorborate, boron trifluoride, zinc chloride, methanesulfonic acid, solid supported acids (e.g. Amberlyst™ 15, Nafion™ NR50)—all of which led to oligomerization. Other catalysts that have were screened include kaolinte, bentonite, Zeolite Y, acidic aluminum oxide, and silica gel. These processes all resulted in no reaction.

We have discovered a two-step process employing methanolysis of an aromatic diepoxide to a dicarbinol followed by an acid-catalyzed rearrangement to successfully produced dialdehydes.

The method comprises:

• • a) combining an alcohol with a diepoxide in the presence of a base to form a first mixture;
  • b) heating said first mixture to form a second mixture;
  • c) adding an acid to the second mixture to form a third mixture; and
  • d) separating dialdehyde from the third mixture.

Di-epoxides suitable for the method include 1,3-bis(2-methyloxiran-2-yl)benzene, 1,4-bis(2-methyloxiran-2-yl)benzene, 1,3-di(oxiran-2-yl)benzene, 1,4-di(oxiran-2-yl)benzene 4,4′-bis(2-methyloxiran-2-yl)-1,1′-biphenyl, and 2,6-bis(2-methyloxiran-2-yl)naphthalene and mixtures thereof.

Acids suitable for the method include acetic acid, formic acid, chloroacetic acid, dichloroacetic acid, trichloroacetic acid, and trifluoroacetic acid and mixtures thereof.

Alcohols suitable for the method include methanol, ethanol, n- and iso-propanol, n-butanol, and sec-butanol and mixtures thereof.

This invention can be further illustrated by the following examples thereof, although it will be understood that these examples are included merely for purposes of illustration and are not intended to limit the scope of the invention unless otherwise specifically indicated.

Abbreviations

wt % is weight percent; hrs or h is hour(s); mm is millimeter; m is meter; GC is gas chromatography; ° C. is degree Celsius; min is minute; t_R is retention time; g is gram; mmol is millimole; mol is mole; mL is milliliter; L is liter; μL is microliter.

EXAMPLES

Example 1: Preparation of 2,2′(1,4-phenylene)bis(1-methoxypropan-2-ol) [2]

KOH (49.2 g, 788 mmol) was dissolved in MeOH (400 mL) contained within a 1 L, 4-necked round-bottom flask fitted with thermocouple, overhead stirrer, and nitrogen inlet atop a reflux condenser. During the addition of KOH, internal temperature reached 60° C. and was maintained there by heating mantle. 1,4-bis(2-methyloxiran-2-yl)benzene [1] was added over the course of 1.5 hrs. The reaction was monitored by ¹H NMR (aliquot was taken and dissolved in DMSO-d₆. Once the di-epoxide was completely consumed, the reaction was cooled to ambient temperature, and acetic acid (47.3 g, 788 mmol) was added dropwise. Once addition was complete, the volatiles were removed under reduced pressure using a rotary evaporator. The residue was taken up in 250 mL of toluene and then washed with 250 mL of water. The aqueous layer was back-extracted with 250 mL of EtOAc using a separatory funnel. The organics were combined, dried with MgSO₄ and simultaneously treated with 5 g of activated carbon. The mixture was filtered, and volatiles were removed under reduced pressure using a rotary evaporator. 2,2′-(1,4-phenylene)bis(1-methoxypropan-2-ol) [2] was isolated as a white solid [LC-MS (Column A) t_R: 3.80 min (Exact mass: 254.15 m/z, found 254.2 m/z)]/.

Example 2: Preparation of 2,2′-(1,4-phenylene)dipropanal [3]

The 2,2′-(1,4-phenylene)bis(1-methoxypropan-2-ol) [2] then dissolved in formic acid (88%, 98.0 g) contained within a 500 mL, 4-necked round-bottom flask fitted with thermocouple, overhead stirrer, and nitrogen inlet atop a reflux condenser. The mixture was heated to 100° C. After 6 hrs, additional formic acid was added (98.0 g). After an additional 2 hrs, GC indicated >99% conversion to 2,2′-(1,4-phenylene)dipropanal [3]. The volatiles were then removed under reduced pressure using a rotary evaporator. The residue was taken up in 250 mL of toluene and then washed with a saturated solution of NaHCO₃. After layer separation, the organics were dried with MgSO₄, filtered, and then concentrated. The crude material was then Kugelrohr—distilled at 150° C./1 mm Hg to isolate the 2,2′-(1,4-phenylene)dipropanal [3] as a colorless oil. GC-MS t_R: 14.47 min (Exact mass: 190.10 m/z, found: 190.1 m/z).

Example 3: Preparation of 2,2′-(1,3-phenylene)bis(1-methoxypropan-2-ol) 5 and 2,2′-(1,3-phenylene)dipropanal [6]

2,2′-(1,3-phenylene)bis(1-methoxypropan-2-ol) [5] was prepared in a similar manner to 2,2′-(1,4-phenylene)bis(1-methoxypropan-2-ol) [2] using the dicarbinol preparation procedure described herein above. [LC-MS (Column B) t_R: 4.55 min, 4.68 min (Exact mass: 254.15 m/z, found 254.2 m/z)]. 2,2′-(1,3-phenylene)dipropanal [6] was prepared using the di-aldehyde preparation procedure described herein above. [GC-MS t_R: 14.22 min (Exact mass: 190.10 m/z, found: 190.1 m/z)].

Instrument Parameters—Agilent 6890N GC with Agilent 5975B VL MSD

Sample Prep: 100 μL sample diluted to 1 mL with toluene; Column: DB-5 30 m×0.25 mm×0.25 μm; Oven Ramp: 0-4.5 mins at 40° C.; Ramp 20 C/min to 280 C, Hold up to 85 mins; Injector: Temperature—250° C.; Split Flow—65 mL/min; Carrier Flow Rate—1.3 mL/min; Volume—1.0 μL; MS: Transfer Line—280° C.; Ion Source Temp—230° C.; Mass Range—34-700 amu.

Conditions—Agilent 1100 LC

• • Sample Prep: 2-3 mg/mL in DMSO
  • Column A: Zorbax™ XDB-C18×4.6 mm, 5 μm
  • Column B: Poroshell™ EC-C18 50×4.6 mm, 2.7 μm
  • Column Temp: 40° C.
  • Injection Volume: 2 μL
  • DAD: 190-600 nm collection
  • Pump Conditions: Initial—97% water (2.5 mM NH₄OAc) (Solvent A) and 3% acetonitrile (Solvent B)
  • Gradient:

• • Mass spectra were acquired with a Micromass LCT mass spectrometer, which was coupled to the LC. Mass spectra were collected using electrospray ionization in both the positive-ion and negative ion modes. Ammonium acetate (50 mM in MeOH) was added post column (0.1 mL/min) to enhance ionization efficiency. ES₊/ES₋ scan range was 60-3300 amu (25 and 75V).

The invention has been described in detail with reference to the embodiments disclosed herein, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.