Formylation process for producing aldehydes

Details Formylation process for producing aldehydes Formylation process for producing aldehydes

1987-04-10

1988-07-05

Reamer, James H.

Organic compounds -- part of the class 532-570 series

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

568347, C07C30119

Patent

active

047556137

DESCRIPTION:

BRIEF SUMMARY
The invention relates to a process for preparing aromatic or heteroaromatic aldehydes by formylation of compounds comprising one or more aromatic or heteroaromatic rings. This invention relates to starting compounds in which the aromatic ring is functionalized by at least one hydroxyl function (in particular phenol compounds) or in which the heteroaromatic ring is nitrogenous (in particular pyrrole compounds).
The Reimer-Tiemann formylation reaction has been known since 1876 and provides for production of phenolic aldehydes from phenols. Interest in this reaction is considerable because the aldehydes so obtained (parahydroxybenzaldehyde or salicylaldehyde) are industrial synthesis intermediates employed in many fields (fine chemistry, pharmacology . . . ); in particular, salicylaldehyde is the forerunner of aspirin.
This reaction comprises placing the initial phenolic compound and chloroform in the presence of an aqueous alkaline hydroxide solution. Since its discovery, this reaction has been modified several times, but its performance has not been significantly improved thereby. Thus, the yield of this reaction is, in the absence of the specific catalyst, about 30% by weight of formed aldehyde with respect to the initial phenol; the best present-day yields are about 50% and have been achieved in the presence of very costly specific catalysts such as ammonium salts or cyclodextrins; (it should be noted that some authors indicate the yield by referring the formed aldehyde to the phenol consumed rather than to the initial phenol, thereby arriving at a higher but spurious value disregarding the substantial residual amounts of phenol). The drawback of low yields achieved to date in the Reimer-Tiemann reaction is accentuated by the fact that the residual phenol is difficult to extract and to recycle, and represents a very serious pollution factor of the aqueous effluents. Moreover, a major drawback of this reaction when applied industrially is its production of substantial amounts of tars which complicates aldehyde extraction. Reference is made to the literature below showing the development of this reaction from its origin to the present: with data on the reaction fundamentals, addition of methanol or ethanol for improving the yield and directing the reaction toward the para-/form, phase-transfer catalyst (quaternary ammonium salt), 39, p 3753, questioning the effects of some phase transfer catalysts, pressurization at high temperature, Co., Ltd), suggesting the use of a phase transfer catalyst combined with an inert solvent, 1-33, survey of this reaction in 1982, 790, stating the extreme difficulty in formylating pyrrole and its derivatives.
These publications together describe a reaction in an aqueous two-phase liquid-liquid medium; the alkaline hydroxide always is added as a more or less concentrated aqueous solution.
Furthermore, the following literature covers the growth of the reaction in an anhydrous solid/liquid medium:
The authors add alkaline hydroxide in solid form and seek the rigorously anhydrous nature of the medium as the mandatory operative condition. To achieve acceptable reaction performance, they add specific catalysts such as N--N dimethylformamide in the case of patent (9) or a surfactant ("Tween 80", "Span 85") for patent (10). However these procedures incur three serious drawbacks: on one hand pollution of the product obtained by the catalyst, and on the other hand a comparatively low yield, and lastly a residue of the initial compounds in the final products.
Indeed, the progress made since 1876 relative to the Reimer-Tiemann reaction has been of little significance, so that the authors of publication (7) state on page 14:
"Even 105 years after its discovery, conditions for the Reimer-Tiemann reaction cannot be said to have been optimized. This is not too surprising for a reaction in which a quantitative yield has never been reported, and in which useful yields (of abnormal products) of 3-10% are not unusual."
The object of the present invention is to provide a new implementation of the

REFERENCES:
patent: 3206513 (1965-09-01), Budde
patent: 3365500 (1968-01-01), Ponty
patent: 3972945 (1976-03-01), Albright
patent: 4584410 (1986-04-01), Hamada et al.
Smith et al., J. Org. Chem., vol. 50, pp. 790-792 (1985).
Deshpande, Chem. Abst.; vol. 66, #55265H (1967).
Hine et al., J.A.C.S., vol. 81, pp. 6446-6449 (1959).

Affiliated with

Also associated with

Rating

Formylation process for producing aldehydes does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Formylation process for producing aldehydes, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Formylation process for producing aldehydes will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2333374