Feb. 5, 1954
945
NOTES
soluble. This observation led Walker to suggest that complex formation might occur (even in s o h tion) between amidinium and carboxylate ions. A complex between these ions would be expected to Experimental be stabilized by the existence of several possible Fluorination of 3-Bromo-l , lt1,4-tetrachlorobutane.Powdered antimony trifluoride (3 moles) was placed in a resonance forms. flask equipped with stirrer and reflux condenser. A stream If such complex formation were to occur in the of chlorine was introduced near the bottom of the flask until particular case of guanidinium ion, i t would be of 90 g. (1.3 moles) had been absorbed. The flask was then great importance in the chemistry of proteins. -411 carefully cooled in an ice-bath to give a thin film of SbF,. SbFsCl2 which could be broken up and dispersed throughout proteins contain guanidinium and carboxylate the organic compound to be fluorinated. After the addition groups on their side chains, and complex formation of CCl3CH2CHBrCH2C1(550 g., 2 moles), vigorous stirring between them could play a role in the maintenance was begun and the mixture allowed to warm to 40-50" of the native protein structure: i t could account, for where it was maintained for three hours. The reaction mixture was made slightly basic with potas- example, for the abnormally large intrinsic ionizasium carbonate and steam distilled to give 356 g. of organic tion constant observed for the carboxyl groups of product. Fractionation through a 40-cm. column packed serum albumin.2 with protruded packing gave 16.5 g. (4.5% conversion) of Accordingly, the experiments described below CF2ClCH2CHFCH2C1,b.p. 38-50' (27 mm.), 274 g. (51% conversion) of CF2ClCH&HBrCH2CI, b.p. 52-57' ( I 1 were performed to test the extent to which guanimm.), and 32 g. (6.2% conversion of CFC12CH2CHBrCH2- dinium ions, as compared to ammonium and potasC1, b.p. 75-85' (11 mm.). sium ions, affect the activity of acetate ions in soluBy carrying out the reaction with antimony fluoride (1 mole), chlorine (0.6 mole) and CClaCH2CHBrCH2Cl (0.5 tion. The method used was intended t o give only mole) a t a maximum temperature of 62", a larger amount the order of magnitude of the interaction, and (20%) of CF2ClCH2CHFCH2Clwas obtained with a decrease a more accurate study had been planned if evidence (17%) in the amount of CF2CICH2CHBrCH2CIformed. for appreciable interaction had been found. It Several experiments were carried out and the products comwas found, however, that complex formation bebined and purified to give the compounds listed in Table I. 1,l-Dichloro-1-fluorobutene-3and 1-Chloro-l ,l-difluoro- tween guanidium and acetate ion is only very weak, butene-3 .-One mole of CCl2FCHzCHBrCH2Cl was added and probably weaker than that between ammonium t o a vigorously stirred sluiry of zinc dust (1.3 moles) in and acetate ions. The association constant (Ka) is methanol (380 ml.) maintained a t the reflux temperature. The reaction was carried out in three hours. The mixture of tlie order of 0.5, ;.e., less than that for associawas steam distilled and the water-insoluble laver separated, tion between the ions of many strong electrolytes dried and fractionated to give 58 g. of CFClZCH2CH=CH2, (e.g., KN01).3 It is much too weak to cause any b.p. 84-92'. appreciable association between guanidinium and By essentially the same procedure, CF2ClCH2CHBrCH2C1 (0.93 mole), zinc dust (1.54 moles) and isopropyl alcohol carboxylate groups of protein molecules. The association constant would have to be ten times as ( I i O ml.) gave a 79% yield of CFzClCHzCH=CH2, b.p. 4753 . great to account for the abnormal pK of the carI-Chloro-l-fluorobutadiene-l,3.-To a refluxing solution boxyl groups of serum albumin.
1,l-Difluorobutadiene polymerized on standing to a rubber-like material. Maleic anhydride did not form an adduct with 1,l-difluorobutadiene.
of CFClnCH&H=CH2 (0.4 mole) in ethanol was added dropwise a solution of potassium hydroxide (0.63 mole) in Experimental 120 ml. of ethanol. The addition was carried out over a Reagent grade chemicals were used without further purifiperiod of 1.5 hours and the mixture was refluxed an additional hour. The product was washed with water, dried and dis- cation. Twenty-five ml. of a solution of 0.0104 M NaOAc tilled to give 23 g. (53.5%) of l-chloro-l-fluorobutadiene-l,3, and 0.0569 M HOAc was placed in a vessel containing a stirrer and Beckman glass and calomel electrodes, which b.p. 52-54.5'. 1,l-Difluor0butadiene.-A solution of potassium hydrox- were connected to a Beckman Model G pH meter. Apide (2.68 moles) in ethanol (450 g.) was slowly added t o proximately 3 M KCl was added from a buret in small inC F ~ C ~ C H Z C H = C (1.66 H ~ moles) in a flask equipped with crements, and the pH measured after each addition. The experiment was repeated using NHdCl and C( NH2)sCl in stirrer, addition funnel and reflux condenser connected to traps cooled in Dry Ice. The heat of the reaction was suffi- place of KC1, and all three determinations were repeated starting with 25 ml. of a solution of 0.0208 M NaOAc and cient t o maintain a gentle reflux. Reflux was maintained for one hour after the addition. The product in the cold 0.0561 M HOAc. A constant temperature of 25.0' was trap was distilled through a vacuum jacketed column t o give maintained. The results are shown in Fig. 1. Volumes were assumed additive in the calculation of concentrations. 50 g. of CFz=CHCH=CHa, b.p. 3.5-5.0'. In Fig. 2 is shown a plot of pH +0.5
