Fill in the blanks with the appropriate vocabulary word or circle the correct bo

Question

Fill in the blanks with the appropriate vocabulary word or circle the correct bold-faced word. A) Halogens are ortho and para/meta directors and activate/deactivate/have no effect in electrophilic aromatic substitution. They donate/withdraw/no effect electrons by induction and donate/withdraw/no effect electrons by resonance. B) Enols and carbonyls interconvert by _____, which can occur in acid/base/both/neither conditions. The _____ form is more stable. C) Alkenes that are Z are always/sometimes/never cis. Alkenes that are trans are always/sometimes/never E. D) Ketones/aldehydes are weaker electrophiles because of induction/resonance other reason. E) The most common mechanism in reactions of alkenes is _____; it typically follows _____ regioselectivity and always/sometimes/never has syn stereoselectivity F) Formation of hemiacetals occurs in acid/base/both/neither and the product is always/sometimes/never isolable; acetal formation occurs in acid/base/both/neither and ethe product is always/sometimes/never isolable with proper workup. G) Addition of an unhindered base to a haloalkane gives the more/less substituted alkene by _____ regioselectivity and a _____ mechanism. This process follows thermodynamic/kinetic control. H) True/False Adding alkyl groups to an alkene increases it's thermodynamic stability and makes it less nucleophilic, and thus slows reaction with mCPBA. I) In^1H NMR of alkenes geminal couplings occur between H that are 2/3/4 bonds apart and generally are 0-3/4-10/6-14/10-18 Hz, these couplings are always/sometimes/never doublets and always/sometimes/never between two alkene H. J) Diels-Alder reactions create up to 0/1/2/4/6 stereocenters and orient by the _____ rule and thus display kinetic/thermodynamic control. Typically the diene is electron rich/poor and the dienophile is electron rich/poor. K) Non-planar conjugated rings react similarly to _____ functional groups L) Strongly basic nucleophiles will tend to add to conjugated carbonyls as 1, 2-addition to the carbonyl/1, 2-addition to the alkene/1, 4-addition. In this case addition of the nucleophile is typically reversible/irreversible/can't say M) Conjugated alkenes are more/less thermodynamically stable and more/less kinetically reactive. The same pattern is/is not followed by cyclic conjugated systems.

Explanation / Answer

Halogens are ortho and para directive,because they have three lone pair of electrons which are present in conjugation with the –C=C- bonds of the ring.Threrfore they show positive resonance effect(i.e.donate electrons by resonance).With positive resonance effect halogens exert –I effect (inductive effect) also and attract the electron of the nucleus towards itself.These two effects act in opposite directions but resonance effect is more strong.As a result the electron density is high at ortho and para positions (and have activating effect in electrophilic substitution).

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