Abstract: The present invention is directed to the process of preparing a peptide comprising reacting a first amino acid or peptide with an amino acid fluoride of the formula: ##STR1## or the acid fluoride salts thereof wherein BLK is an N-amino protecting groupAA is an amino acid residue andX is H or a protecting group useful,and the first amino and peptide have a free amino group and a blocked carboxy end.

Abstract: A compound of the formula ##STR1## or the acid fluoride salts thereof wherein BLK is an N-amino protecting group or hydrogenAA is an amino acid residue andX is H or a protecting group useful as a coupling agent in peptide synthesis.

Abstract: A perfluoroalkyl halogenide represented by the formula: ##STR1## wherein X stands for one element selected from the group consisting of iodine and bromine, R.sub.f for a perfluorohydrocarbon group, n for an integer in the range of 1 to 3, and m for an integer in the range of 1 to 3, provided that n and m satisfy the relationship, n.gtoreq.m, is produced by a method which consists essentially in subjecting a perfluorocarboxylic acid fluoride represented by the formula, ##STR2## wherein R.sub.f and n have the same meanings as defined above, to a thermal reaction with a lithium halogenide represented by XI, wherein X has the same meaning as defined above.

Abstract: Herbicidal bis-formyl-N-aryl-N'-alkyl ureas having the formula ##STR1## in which X and Y are the same or different and are selected from the group consisting of trifluoromethyl, chloro, bromo, fluoro, hydrogen, cyano, alkyl, thioalkyl, halothioalkyl, alkoxy and sulfonylalkyl, wherein the alkyl groups have from one to four carbon atoms; andR is alkyl wherein the alkyl groups have from one to four carbon atoms and methods of use are disclosed and claimed.