Methylidene malonate process

Abstract

Novel improved processes for the production and isolation of methylidene malonates via direct and indirect adduct processes.

Description

RELATED APPLICATION[0001]This application is a continuation of pending U.S. patent application Ser. No. 12 / 774,831, filed May 6, 2010 which claims the benefit of U.S. Provisional Patent Application Ser. Nos. 61 / 215,610 and 61 / 215,578, both of which were filed on May 7, 2009 and entitled Improved Methylidene Malonate Process, and the benefit of U.S. Provisional Patent Application Ser. No. 61 / 291,898, filed Jan. 3, 2010; entitled Methylidene Malonate Process, all of which are hereby incorporated herein by reference in their entirety.FIELD OF THE INVENTION[0002]The present invention relates to improved processes for the production of methylidene malonates as well as the methylidene malonates produced thereby and the use thereof.STATE OF THE ART[0003]Methylidene malonates are compounds having the general orwherein R1 and R2 may be the same or different and represent H or a C1 to C18 hydrocarbon group or heterohydrocarbon group having one or more nitrogen, halogen, or oxygen atoms; provi...

AI Technical Summary

Benefits of technology

This approach achieves consistent yields exceeding 25% with high purity, often above 80%, reducing impurities and byproducts, and stabilizes the products for bulk storage, thereby improving the commercial feasibility of methylidene malonates.

Problems solved by technology

Yet, despite all the promise, these compounds have found limited commercial success owing to the difficulty of their production; the poor, though improving, yet still erratic, yields, and the general instability of these compounds and their production.

The former was unsatisfactory due to very low yield and expensive starting materials.

The latter, though periodically giving better yields than the iodide process, gave relatively poor yields and, more critically, was widely inconsistent from batch to batch, even under the same conditions.

D'Alelio (U.S. Pat. No. 2,330,033), on the other hand, alleged that such processes were erratic and more often produced yields that averaged 10 to 12 per cent.

The resultant mass was then subjected to vacuum distillation at low temperature to separate an allegedly high purity methylidene malonate, though with a low yield.

In discussing the critical need for high purity materials, Coover et. al. draw particular attention to the extreme sensitivity of their monomers to the presence of even small amounts of acidic and basic impurities, the former inhibiting polymerization leading to sluggish and ineffective adhesive activity and the latter accelerating polymerization leading to unstable and useless products.

Unfortunately, other than discussing its limitations with respect to the acidic and basic impurities, and despite its contention of high purity materials, Coover et. al. never provide any data pertaining to the purity of their materials.

These efforts, despite their gains in yield and / or purity, still failed to achieve commercial success.

Citing numerous disadvantages of the foregoing processes, which disadvantages were said to make them difficult, if not impossible, to adapt to industrial scale, Bru-Magniez et. al.

Based on conversations with the successors to the Bru-Magniez technology, efforts to commercially produce the material have met with great difficulty owing to the high instability of the overall production process and final products.

Indeed, they reported a high failure rate: of the limited batches that actually survived through crude distillation, the resultant products had to be stored in a freezer even after stabilizing with upwards of 50,000 ppm SO2 due to their high instability and spontaneous polymerization.

Indeed, our own attempts to follow the prior art processes, including the Bru-Magniez process, most often resulted in failure owing to sublimation of the paraformaldehyde, a failure to produce the desired product (as evidenced by a lack of double bonds in the reaction product), and, more frequently, polymerization of the reaction mix and / or the crude yield.

Even when a successful run was realized, it has now been found that the purity of the materials was quite low.

Consequently, though yields were presumably higher than achieved by other methods, purity was not as high as hoped and, as found through subsequent effort, repeatability was erratic at best.

While the use of intermediate adducts promoted higher yields and allowed greater versatility, particularly with respect to the broader variety of methylidene malonates capable of being produced, lingering problems persisted, namely batch-to-batch inconsistency and the general instability of the process as well as the so-formed crude and final products, especially in bulk storage, and of formulated products, such as adhesives, made with the same.

Additionally, the adduct routes involve considerable added expense, particularly in light of the need for the additional reactants and other materials, added production steps and time, new energy requirements and environmental concerns, and the like.

Furthermore, despite their advances, these processes have yet to fully or even adequately address, particularly from a commercial viability standpoint, the underlying and critical problems evidenced by the continuing inconsistency in the production of the methylidene malonates, particularly as reflected by the ongoing instability of the reaction mix particularly during the distillation and recovery of the desired product as well as of the recovered product.

It is this erratic nature of the production process and resultant product and the attendant costs associated therewith that compromises and overshadows the commercial value and opportunity for these products.

However, it has also been found that yield alone is not sufficient.

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