2.6-Dialkyl-phenols exhibit little steric hindrance on reaction with phosphoryl chloride unless the alkyl substituent is bulky (i.e. t-butyl). Where bulky substituents are present reaction with phosphoryl chloride occurs only in the presence of Friedel-Crafts type catalysts after either a dealkylation or a rearrangement of the ortho-placed alkyl groups, followed by U-phosphorylation, has occurred. DIALKYLANILINES react with phosphoryl chloride and phosphorus trichloride by C-phosphorylation a t the @ava-position both in the presence specific Friedel-Crafts type catalysts to give mixtures of products containing from One to three phosphorust Present address:
Vol. 67 rate distilled at 195-200°(2 mm.) as a colorless oil; yield 145 g. or 44%.; «" 1.4797; d-st 0.955; sapn. no., 167 ; caled. 169).The 2-ethyl hexoate, benzoate and furcate (see Table I ) were prepared in a manner similar to the laurate. The yields were between 50 and 65%.Dihydro-nor-dicyclopentadienyl Isothiocyanate (E or F).-A mixture of 132 g. of dicyclopentadiene, 75 g. of water, and 76 g. of ammonium thiocyanate was rapidly stirred and heated at 90-95°under a reflux condenser.To the hot, stirred solution, 100 g. of concentrated hydrochloric acid (37% HC1) was added dropwise during the course of one hour while the reaction mixture was maintained at 90-95°and rapidly agitated. The mixture was then stirred for three hours longer at 90-95°, filtered hot by suction to remove traces of polythiocyanic acid, and the dear, filtered oil layer was separated, washed with water and distilled in vacuo. The product distilled at 127-132°1 2 mm.) as a pale yellow oil, having a characteristic odor; yield 120 g. or 62%. The analytical sample boiled at 140-142°( 6 mm.); «"d 1.
Synthesis of tetramethylene-and trimethylene-phosphiic acid was accomplished by organometallic routes. These acids and the previously reported pentamethylenephosphinic acid were shown to possess acidic dissociation constants indicative of stronger acidic properties than shown by analogous dialkylphosphinic acids.IN continuation of a study of acidic properties of acids of phosphorus,l we prepared and examined tetramethylene-and trimethylene-phosphinic acid (I ; n = 2 'CH'\PO*oH and 1, respectively), as progressively more strained cyclic analogues of [CH2'fl'cH2'(1) the previously reported pentamethylenephosphinic acid.2 The yield of tetramethylenephosphinic acid, prepared as described for the pentamethylene analogue,2 was only 0.1% and, although models show no steric strain to account for this, they do account for the still smaller yield of the trimethylene analogue: which was prepared by ring closure of 3-bromopropylphosphonic dichloride, with magnesium, because of the impossibility of preparing the bifunctional Grignard reagent from 1 : S-dibromopropane.The apparent pK values for acidic dissociation of these acids, as well as for the analogous dialkylphosphinic acids, are shown in the Table.
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