1-pentyne trans

The Rh and Ir complexes 85-88 (Fig. 2.14) have been tested for the intramolecular hydroamination/cyclisation of 4-pentyn-l-amine to 2-methyl-1-pyrroline (n = 1). The reactions were carried out at 60°C (1-1.5 mol%) in THF or CDCI3 The analogous rhodium systems were more active. Furthermore, the activity of 87 is higher than 85 under the same conditions, which was attributed to the hemilabihty of the P donor in the former complex, or to differences in the trans-eSects of the phosphine and NHC ligands, which may increase the lability of the coordinated CO in the pre-catalyst [75,76]. 

Figure 11.2. Hydrogenation of 1-pentyne following hydrogenation of trans-2-pentene for Ih.

This suggests that the iran5 -2-pentene is more strongly bound than the pentyne and that the slow rate of hydrogenation may be due to strong adsorption rather than the thermodynamic stability of the trans-isovaer. 

The structure of 4 -propyl-4/3,5/3-cthcnopregnanc-3,20-dione (131) as the main product of photochemical [2 + 2] cycloaddition of 1-pentyne to progesterone and 4a,5a-analogue 138 was confirmed by X-ray analysis. The CD data of 131-140 were in agreement with A/B-cis and AfB-trans fusion in 131 and 138, respectively, and with the cyclobutene ring (main perturber of the C=0 n —> jr transition) lying in a (—)-octant of 131 and a (+)-octant of 138323. 

To compare the properties of alkanes, alkenes, and alkynes, you will be working with compounds that have the same number of carbon atoms. First, you will construct and compare butane, trans-2-butene, 2-butyne, and cyclobutane. You will use a graph to compare the boiling points of each compound. Next, you will use what you have just observed to predict the relative boiling points of pentane, trans-2-pentene, 2-pentyne, and cyclopentane. You will construct and compare these structures and graph their boiling points. 

Predict the structural formula for each compound. After completing steps 1 to 4, predict what the graph of the boiling points of pentane, trans-2-pentene, 2-pentyne, and cyclopentane will look like. 

Repeat steps 1 to 3 for pentane, trans-2-pentene, 2-pentyne, and cyclopentane. 

Problem 8.33 Show reagents and reactions needed to prepare the following compounds from the indicated starting compounds, (a) Acetylene to ethylidene iodide (1,1-diiodoethane). (b) Propyne to isopropyl bromide, (c) 2-Butyne to racemic 2,3-dibromobutane. (d) 2-Bromobutane to trans-2-butene. (e) n-Propyl bromide to 2-hexyne. (/) 1 -Pentene to 2-pentyne. ... 

C8H14 3-ethyl-3-methyl-1 -pentyne 919-12-0 13.641 149.256 1.2 14865 C8H16 1-methyl-trans-2-ethylcyclopentane 930-90-5 15.763 146.706 1,2... 

CH3CH=CHCH3 trans-2-butene 0.9 CH3CH2C=CCH3 2-pentyne 55... 

Problem 12.46. Which of the following exist as a pair of cis and Irons isomers Show structures of the cis and trans isomers, (a) 4-Methyl-2-pentene, ib) 2,4-dimethyl-2-pentene, (c) 4-methyl-2-pentyne, (dichloro-cyclopropane, (e) 1,2-dichlorocyclopropane. 

Indicate whether each of the following molecules is capable of geometrical (cis-trans) isomerism. For those that are, draw the structures (a) 1,1-dichloro- 1-butene, (b) 2,4-dichloro-2-butene, (c) 1,4-dichlorobenzene, (d) 4,5-dimethyl-2-pentyne. 

The requirement for photoinitiation indicates that a radical-chain mechanism must be involved. Chlorination of 1-pentyne carried out in a gas phase reactor at higher temperatures and with higher chlorine ralkyne ratios gives both the trans-dichloroaU kene and the saturated tetrachloro compound derived from addition of a second mole of chlorine ... 

Dimethyl-2-pentyne Acetaldehyde 3,5,5-Trimethyl-trans-3-hexen.2-ol 69... 

Chloro-l-pentyne Propionaldehyde 8-Chloro-trans-4-octen-3-ol 47... 

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