J . Am. Chem. SOC.1986, 108, 1306-1307
1306
Chart I
Table I. NMR Viscosity Determination samole
T. "C
Fe,
HZ
UNMP.C
CSt
Yf1hh.d
CSt
EG" 23 32.62 f 0.2 14.85 14.57 f 0.09 EG/D,O 23.5-23.8 17.55 f 0.26 7.98 7.84 A 0.10 (80:20 v/v) EG/CH3CN 23.0 f 0.5b 11.21 f 0.25 5.10 5.16 f 0.01 (80:20v:v) Carbowax 600/ 15.23 f 0.25 6.93 6.94 f 0.12 Me,SO 34'0 0'5b 15.27 f 0.25 6.95 (20% w/w) "EG = ethylene glycol. bActual temperature calculated with a C-13 thermometer insert (acetone-d6/CCI4; 1:l v/v). Led, J. L.; Petersen, S. G. J . Magn. Reson. 1978, 32, 1. = FJ219.7 (Stokes) for 5-mm o.d./ NMR tube inside 10-mm tube. a = 0.24765 cm, b = 0.45085 cm, q = 0.5493, T, = 5614.5. dViscosity measured with Ubbelohde viscometer.
*
where k is an arbitrary constant. The intercept of this linear plot gives F,. Substitution of F, into eq 2 gives the kinematic viscosity of the liquid. The results obtained for several test liquids are shown in Table I. Viscosities determined by using a conventional Ubbelohde viscometer and the N M R values agree within 2%. The experiment is independent of the choice of nucleus. Both homonuclear and heteronuclear measurements are feasible provided peak separation is larger than the gradient width. Individual components in a mixture give the same viscosity as the fluid flow is governed by the bulk viscosity (cf. Carbowax 600/Me2S0 mixture). An implication of the current work is that an N M R image of coherent linear flow should be detectable in a rotating magnetic field.
nilrosoalkene
vinyl nitrosonium cation
Scheme I
'U yleld, %
( E ) - ] ,R' = CH,; R2 = H (E,E)-2,R ' = CH,; R 2 = R3 = H
Intramolecular [4 with Olefinst
+ 21 Cycloadditions of Nitroalkenes
79
( Z ) - 1 ,R ' = H ; R2 = CH3 ( E , Z ) - 2 ,R' = R' = H ; R 2 = CH 3 96 (E,E)-3,R 1 = R3 = CH,; R2 = H3 89 ( Z , E ) - 3 ,R' = R3 = CH,; R2 = H Scheme I1
1 -
-6
85%
59%
Table I. Cycloadditions of Nitroalkenes 2 and 3".*
Acknowledgment. The generous financial support of Eli Lilly & Co. is gratefully acknowledged. M. Vera was supported by a Committee on Institutional Cooperation (CIC) Minority fellowship. The continued instrumental expertise of Dr. R. Santini is gratefully acknowledged. Supplementary Material Available: N M R image of TVF in ethylene glycol as a function of axial field gradient strength and a table of a, b, d , q, T, F J v , and v values (3 pages). Ordering information is given on any current masthead page.
nitroalkene
trans
CIS
4 , R3 = H 5, R3 = C H I substrate
solvent
temp, O C
time, h
trans
cis
yield,c 5%
2.25 52 48 59 (E,E)-2 CH2C12 -70 2.25 75 25 68 ( E , Z ) - 2 CH2C12 -70 (E,E)-3" toluene -29 0 3 >98
