Sn1 reactions in alkyl halides?
usually Sn1 rxn undergoes only with secondary and tertiary alkyl halide and with primary the most favourable rxn would be sn2. So I dont think that alkyl halide would actually undergo such a unfavourablle rxn mechs.
Which of the following statements correctly describe(s) E2 reactions of alkyl halides (RX)?
Which of the following statements correctly describe(s) E2 reactions of alkyl halides (RX)?? I. Rate= k[base] II. Rate=k[base][RX] III. Rate=k[RX] IV. The reaction occurs in two or more distinct steps V. Rearrangements are sometimes seen A) I and V B) III and V C) II only D) III only E) IV only F) II and IV G) none of the above
O-chem: Which one of the following statements does not correctly describe Sn1 reactions of alkyl halides?
( > means "reacts faster than") a) Carbocations are intermediates in Sn1 reactions. b) The order of alkyl bromide reactivity is R3CBr > R2CHBr > RchBr > CH3Br. c) The rate of an Sn1 reactions depends on the concentration of the alkyl halide. d) The rate of an Sn1 reactions depends on the concentration of the nucleophile. Why?
Which of the following does not correctly describe SN2 reactions of alkyl halides?
Which of the following does not correctly describe SN2 reactions of alkyl halides? A. Tertiary halides react faster than secondary halides. B. Rate of reaction depends on the concentrations of both the alkyl halide and the nucleophile. C. The mechanism sonsists of a single step with no intermediates. D. The transition state species has a pentavalent carbon atom.
How do u rank reactivity of alkyl halides in Sn1 reactions?
They should be ranked as follows: E, B, D, A, C, F E is the fastest, because it will form a highly substituted, tertiary carbocation when the leaving group leaves. B is not as substituted (has a hydrogen instead of a methyl group), so slower. D and A come next, but D is faster than A, because iodine less electronegative, larger, and thus a better leaving group. C is less substituted than D and A, so slower. Finally, F will only form a primary carbocation, which is not at all favored and is thus the slowest reaction.
Sec.alkyl halides give SN1 reaction in the presence of polar solvents. give reason?
The other answer is only partially correct but is suggestive of the answer. The main reason polar solvents are important is due to the intermediate that is formed during the reaction. When you draw out the mechanism for the Sn1 reaction, there is an intermediate carbocation. It is a very high energy species that needs stabilization. A polar solvent has both a positively and negatively charged end. The positive charge of the intermediate causes the solvent to organize (one form of solvation) around the cation with the negative end of the solvent pointed toward the positively charged carbocation. This helps to stabilize the cation which makes it more likely to form. If it can't form then the reaction cannot happen. Anything that helps stabilize the intermediate will help the reaction proceed.
Which of the following alkyl chlorides will most likely undergo an SN1 substitution reaction?
(c) because in sn1 carbocations are intermediates ...therefore greater the stability of carbocation more easily will be the substitution ,,faster is the reaction .....since the stability of carbocation decreases in order : 3degree>2degree>1degree so reactivity of alkyl halide decreases in the same order:3 degree alkyl halide>2 degree alkyl halide>1 degree alkyl halide and among the options given above only option (c) is a 3 degree alkyl halide....
Why are aryl halides less reactive than alkyl halides towards nucleophilic substitution reactions?
Aryl halides are the compounds in which halogen atom is attached to sp² hybridised carbon atom of benzene ring whereas in alkyl halides halogen is attached to sp³ hybridised carbon atom . Reactivity of nucleophilic substitution reactions depends upon several factors like nature of leaving group (Group which depart from substrate ),bond dissociation enthalpy of C-X bond , solvent used .In aryl halides non bonding electron pair of halogen atom are in conjugation with the benzene ring which confers partial double bond character to C-X bond .Another important consideration is hybridisation of carbon atom to which halogen atom is attached ,in case of aryl halides it is sp² hybridised which reduces the polarity of C-X bond and hence increases bond dissociation enthalpy of C-X bond .This is the chemistry of aryl halides .Now come to the alkyl halides.Carbon atom to which halogen is attached is sp³ hybridised which confers greater polarity to C-X bond and hence lower bond dissociation enthalpy .In this case non bonding electron on halogen atom is not in conjugation with alkyl group so C-X bond is purely single bond which requires less energy to break than a partial double bond .Another factor which affects reactivity is stability of carbocation formed .Aryl carbocation is not stabilized by resonance .This is the story of aryl halides and alkyl halides which greatly affect the reactivity towards nucleophile.