A unique two-step process is disclosed for the surprisingly high rate of amidation of vinyl chloride (VCl) with carbon monoxide and certain amines catalyzed by an effective amount of monodentate tertiary phosphonium complexes of Pd(0). The rate is orders of magnitude faster than that of other monochloroalkenes. When compared with the three chloropropenes, the simplest alkyl-substituted derivatives of VCl, rates differ by a factor of about 40 to 70 with ammonia as the amine. The reaction product with VCl is mainly the Michael adduct of the amine with the acrylamide produced. However, the chloroprenes give the propenamides with retention of configuration in the case of cis- and trans-1-chloropropene, and no adduct formation. The formation of this adduct has an important influence on catalyst stability since it can compete with the addition of the tertiary-phosphonium ligand from the catalyst complex. The latter reaction produces small amounts of a phosphonium chloride, and the resulting loss of ligand causes palladium metal to separate, thereby deactivating the catalyst. This understanding enables one to choose the best ligand/amine combination to suppress this catalyst deactivation mechanism. Triphenylphosphine and dimethylamine is a particularly effective combination.
The present invention is directed to a process for preparing an aromatic amide. More specifically, the process involves reacting carbon monoxide, an amine and an aromatic chloride in the presence of an iodide or bromide salt, a catalyst, and a base.
A continuous process for making N,N-dimethylacrylamide (NNDMA) is disclosed which uses a commodity chemical, namely vinyl chloride (VCl), which is amidated with dimethylamine (DMA) and carbon monoxide in the presence of a supported palladium(O) triorganophosphine catalyst used under conditions where the ratio of P/Pd is critical. The continous process unexpectedly provides the catalyst with long life because the reaction can be carried out in a moving bed of catalyst in the presence of enough acetonitrile solvent to prevent deposition of DMA.HCl, formed during the reaction, in the pores of the catalyst support.
A process for the preparation of arylamides of heteroaromatic carboxylic acids of the formula: ##STR1## in which each A.sup.n is nitrogen or CR.sup.n (n=1 to 5), with the proviso that at least one of the ring members is nitrogen and that two nitrogen atoms are not bonded directly to one another; R.sup.1 to R.sup.5, if present, independently of one another are hydrogen, C.sub.1-4 -alkyl or aryl, one of the substituents R.sup.1 to R.sup.5 being a group of the formula --OR, in which R is an optionally substituted aromatic or heteroaromatic radical; R.sup.6 is hydrogen or C.sub.1-4 -alkyl; and R.sup.7 is an optionally substituted aromatic or heteroaromatic radical. The amides are obtained from the corresponding heteroaromatic halogen compounds, the corresponding aromatic amines and carbon monoxide in the presence of a palladium phosphine complex. Compounds of this class are important herbicides.
A process for the preparation of arylamides of heteroaromatic carboxylic acids of the formula: ##STR1## in which each A.sup.n is nitrogen or CR.sup.n (n=1 to 5), with the proviso that at least one of the ring members is nitrogen and that two nitrogen atoms are not bonded directly to one another; R.sup.1 to R.sup.5, if present, independently of one another; C.sub.1-4 -alkyl or aryl, one of the substituents R.sup.1 to R.sup.5 being a group of the formula --OR, in which R is an optionally substituted aromatic or heteroaromatic radical; R.sup.6 is hydrogen or C.sub.1-4 -alkyl; and R.sup.7 is an optionally substituted aromatic or heteroaromatic radical. The amides are obtained from the corresponding heteroaromatic halogen compounds, the corresponding aromatic amines and carbon monoxide in the presence of palladium diphosphine complex. Compounds of this class (Formula I) are important herbicides.
A process for the preparation of arylamides of heteroaromatic carboxylic acids of the formula: in which each A.sup.n is nitrogen or CR.sup.n (n=1-5), with the proviso that at least one of the ring members is nitrogen and that two nitrogen atoms are not bonded directly to one another; R.sup.1 to R.sup.5, if present, independently of one another are hydrogen, C.sub.1-4 -alkyl or aryl, also one of the substituents R.sup.1 to R.sup.5 can be a group of the formula --OR, in which R is an optionally substituted aromatic or heteroaromatic radical; R.sup.6 is hydrogen or C.sub.1-4 -alkyl; and R.sup.7 is an optionally substituted aromatic or heteroaromatic radical. The amides are obtained from the corresponding heteroaromatic halogen compounds, the corresponding aromatic amines and carbon monoxide in the presence of a palladium diphosphine complex. Compounds of this class, especially those in which one of the substituents R.sup.1 to R.sup.5 is an aryloxy group, are important herbicides.
