Crystal and molecular structure of trans-2,trans-3-dimethylcyclopro-panecarboxylic acid

Abstract

Crystals are monoclinic, space group P2,/c, with Z = 4, in a cell of dimensions : a = 6.39. b = 10.98, c = 9.76 8, p = 105.6". The structure w a s solved by direct phase-determining methods and refined by full-matrix leastsquares calculations to R 0-085 over 638 reflections. The crystals contain centrosymmetric hydrogen-bonded dimers with a conformation in which the C=O bond points over the cyclopropane ring.DURING their investigations on the mechanism of cyclopropane formation from epoxides via the Wittig reaction, Ghirardelli and Izydore obtained mixtures of isomeric 2,3-dimethoxycyclopropanecarboxylic acids, (1)-( 111) , from reactions involving ( + ) -(2R,3R) -2,3-epoxybutane and cis-2,3-epoxybutane. I n order that an analysis of the reaction mechanism could be made, it was imperative that the identity of each isomer be established unequivocally. The constitution of (I) was inferred from its optical activity. One of the other two isomers was isolated from the product mixture as a solid, 1ii.p. 79--80.5", and we have subjected it to single-crystal R. G. Ghirardelli and R. ,4. Izydore, personal communication.X-ray analysis to determine its configuration We here report the results of this analysis. EXPERIMENTAL Crystal Data.-C,H,,O,, n1.p. 79-80-5", M = 114.1. Monoclinic, a = 6.39(1), b = 10-98(2), c = 9.76(2) A, 1.148, F(000) = 248. Cu-K, radiation A = 1.542 -4, p(Cu-K,) = 7.1 cm-l. Space group P2Jc (C&J from systematic absences: OkO when k # 2n and h0Z when 1 # 2n.Crystallografihic Measurements.-The crystals have a tendency t o sublime at room temperature, and so those used for the data collection were sealed in thin-walled glass capillaries. Unit-cell dimensions were evaluated from

Structure and disorder of dicalcium barium cyclopropanecarboxylate

“…The bond lengths and angles are given in Table 1 and can be seen to be similar to those in DBP. The molecular geometry agrees well with that found in t-2,t-3dimethyl-r-1-cyclopropanecarboxylic acid (Luhan & McPhail, 1972). In Fig.…”

Substituted cyclopropanes. 8. 2,2,3,3-Tetramethylcyclopropanecarboxylic acid

“…The distortion of each of the two geminal dimethyl groups is thus a bending of the whole CMe2 moiety away from the carboxyl group. The average CCC(methyl) angle of the dimethyl acid (120.7°; Luhan & McPhail, 1972) is somewhat larger than expected. This is probably associated with the cis position of the two vicinal methyl groups, but may also be a consequence of crystal packing.…”

“…The most interesting result is that the average ring bond length is 1.520 A, which is about 0.016/~ longer than the average of many structures with carbonyl and carboxyl substituents (1.504 A; Allen, 1980). In the 2,3-dimethyl-substituted acid (Luhan & McPhail, 1972), the average is 1.503 A. The difference between the average adjacent and the opposite ring bonds is 0.037 A in the dimethyl, but 0.048 A in the tetramethyl derivative.…”

“…Cyclopropanecarboxylic acid melts at 292 K. In the literature, the structure of trans,trans-2,3-dimethylcyclopropanecarboxylic acid has been reported (Luhan & McPhail, 1972). Since methyl groups do not significantly affect the cyclopropane geometry (Klein & Schrumpf, 1981), the geometry of this molecule might be considered to be close to the hitherto unknown structure of the unsubstituted acid.…”

cis-2-Ethoxy-1-phenylsulfinylcyclopropane

“…1.45 (2) C(6)C(7)C(8) 122 (1) C(7)C(8)C(9) 121 (1) C(8)C(9)C(10) 118 (1) C(9)C(10)C(11) 122 (1) C(10)C(11)C(6) 119 (1) C(11)C(6)C (7) 117.7 (9) C(1)C(2)0(12) 117.2 (9) C(3)C (2)0(12) 118.1 (8) C(2)0(12)C(13) 109.9 (8) 0(12)C(13)C(14) 109 (1) 14-13-0(12)-2 178.4 (8) 13-0(12)-2-1 -150.5 (9) 13-0(12)-2-3 -81 (1) 0(12)-2-I-S(4) 6 (1) 2-1-S(4)-5 158.5 (8) 2-3-1-S(4) 111 (1) 3-1-S(4)-6 -160 (1) propane bond, 1.49 (2) A, and the small opposite angle, 58.2(7) °, are common features in cyclopropane compounds such as trans-2,trans-3-dimethylcyclopropanecarboxylic acid (Luhan & McPhail, 1972), 1 -chloro-1-phenylsulfonyl-2,3-dimethylcyclopropane (Saenger & Schwalbe, 1971) and methyl 1carbamoylcyclopropane-l-carboxylate (de Jong & Schenk, 1973). The cyclopropane ring and the plane of the phenyl ring make an angle of 23 (2) °.…”