The present invention relates to the field of herbicides, in particular to a preparation method for a 2-chloro-4-fluoro-5-(3-methyl-2,6-dioxo-4-(trifluoromethyl)-3,6-dihydropyrimidin-1(2H)-yl) benzoate compound of formula (I). The present invention constructs a uracil ring under an acidic condition, and the intermediate prepared by this method can be used to prepare a novel high-efficiency uracil herbicide of structural formula (I), which has stable chemical properties and better herbicidal activity. The synthesis route is simple, and has broad application prospects in agriculture. The present invention further provides intermediate compounds used in the method, as well as methods for producing the intermediate compounds.

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The present invention relates to a method for preparing primary amides from tertiary or secondary amides substituted with various alkyl groups through a transamidation reaction without a metal catalyst in room-temperature conditions by adding ammonium carbonate ((NH.sub.4).sub.2CO.sub.3), wherein the method is eco-friendly since various secondary and tertiary amides that are not toxic or corrosive are used as starting materials and ammonium carbonate ((NH.sub.4).sub.2CO.sub.3) that is neither a strong acid nor a strong base is used, and the method is economical since various primary amides can be synthesized with an excellent yield at room temperature without a metal catalyst.

The present invention relates to a method for preparing primary amides from tertiary or secondary amides substituted with various alkyl groups through a transamidation reaction without a metal catalyst in room-temperature conditions by adding ammonium carbonate ((NH.sub.4).sub.2CO.sub.3), wherein the method is eco-friendly since various secondary and tertiary amides that are not toxic or corrosive are used as starting materials and ammonium carbonate ((NH.sub.4).sub.2CO.sub.3) that is neither a strong acid nor a strong base is used, and the method is economical since various primary amides can be synthesized with an excellent yield at room temperature without a metal catalyst.