In organic chemistry, an electrophile is an electron pair acceptor. Electrophiles are positively charged or neutral species having vacant orbitals that are attracted to an electron rich centre, it participates in a chemical reaction by accepting an electron pair in order to bond to a nucleophile. Because electrophiles accept electrons, they are Lewis acids. Most electrophiles are positively charged, have an atom that carries a partial positive charge, or have an atom that does not have an octet of electrons, they appear to attract electrons as well and seem to behave as though they are empty. These empty substances thus require an electron rich center, thus they are filled. Electrophiles can be observed as photo-sensitive; the electrophiles are attacked by the most electron-populated part of one nucleophile. The electrophiles seen in the organic syntheses are cations such as H+ and NO+, polarized neutral molecules such as HCl, alkyl halides, acyl halides, carbonyl compounds, polarizable neutral molecules such as Cl2 and Br2, oxidizing agents such as organic peracids, chemical species that do not satisfy the octet rule such as carbenes and radicals, some Lewis acids such as BH3 and DIBAL.
These occur between alkenes and electrophiles halogens as in halogen addition reactions. Common reactions include use of bromine water to titrate against a sample to deduce the number of double bonds present. For example, ethene + bromine → 1,2-dibromoethane: C2H4 + Br2 → BrCH2CH2BrThis takes the form of 3 main steps shown below. Forming of a three-membered bromonium ion The alkene is working as an electron donor and bromine as an electrophile; the three-membered bromonium ion 2 consisted of two carbon atoms and a bromine atom forms with a release of Br−. Attacking of bromide ion The bromonium ion is opened by the attack of Br− from the back side; this yields the vicinal dibromide with an antiperiplanar configuration. When other nucleophiles such as water or alcohol are existing, these may attack 2 to give an alcohol or an ether; this process is called AdE2 mechanism. Iodine, sulfenyl ion, mercury cation, dichlorocarbene react through similar pathways; the direct conversion of 1 to 3 will appear.
A β-bromo carbenium ion intermediate may be predominant instead of 3 if the alkene has a cation-stabilizing substituent like phenyl group. There is an example of the isolation of the bromonium ion 2. Hydrogen halides such as hydrogen chloride adds to alkenes to give alkyl halides in hydrohalogenation. For example, the reaction of HCl with ethylene furnishes chloroethane; the reaction proceeds with a cation intermediate, being different from the above halogen addition. An example is shown below: Proton adds to one of the carbon atoms on the alkene to form cation 1. Chloride ion combines with the cation 1 to form the adducts 2 and 3. In this manner, the stereoselectivity of the product, that is, from which side Cl− will attack relies on the types of alkenes applied and conditions of the reaction. At least, which of the two carbon atoms will be attacked by H+ is decided by Markovnikov's rule. Thus, H+ attacks the carbon atom that carries fewer substituents so as the more stabilized carbocation will form.
This is another example of an AdE2 mechanism. Hydrogen fluoride and hydrogen iodide react with alkenes in a similar manner, Markovnikov-type products will be given. Hydrogen bromide takes this pathway, but sometimes a radical process competes and a mixture of isomers may form. In the case of dialkyl-substituted alkynes, the intermediate vinyl cation that would result from this process is unstable. In such cases, the simultaneous protonation and attack of the alkyne by the nucleophile is believed to take place; this mechanistic pathway is known by the Ingold label AdE3. Because the simultaneous collision of three chemical species in a reactive orientation is improbable, the termolecular transition state is believed to be reached when the nucleophile attacks a reversibly-formed weak association of the alkyne and HCl; such a mechanism is consistent with the predominantly anti addition of the hydrochlorination product and the termolecular rate law, Rate = k2. In support of the proposed alkyne-HCl association, a T-shaped complex of an alkyne and HCl has been characterized crystallographically.
In contrast, phenylpropyne reacts by the AdE2ip mechanism to give predominantly the syn product. In this case, the intermediate vinyl cation is formed by addition of HCl because it is resonance-stabilized by the phenyl group; the lifetime of this high energy species is short, the resulting vinyl cation-chloride anion ion pair collapses, before the chloride ion has a chance to leave the solvent shell, to give the vinyl chloride. The proximity of the anion to the side of the vinyl cation where the proton was added is used to rationalize the observed predominance of syn addition. One of the more complex hydration reactions utilises sulfuric acid as a catalyst; this reaction occurs in a similar way to the addition reaction but has an extra step in which the OSO3H group is replaced by an OH group, forming an alcohol: C2H4 + H2O → C2H5OHAs can be seen, the H2SO4 does take part in the overall reaction, however it
Gordon "Felix" Mills, was a composer and conductor during the Golden Age of Radio in the 1930s and 1940s. He was the musical director for The Mickey Mouse Theater of the Air, a Disney radio show of the 1930s. Mills created a "gadget band" with wild instruments for Donald Duck to direct on some episodes, he created arrangements for the show. Mills conducted his own band, appeared in the Hollywood Bowl. Mills was the musical director for CBS Radio's Silver Theater from 1937 to 1947. Mills chose to retire rather than fire some band members during the Red Inquisition. Mills died on April 1987 in Morro Bay, California. Nielsen Business Media, Inc.. Billboard. Nielsen Business Media, Inc. pp. 28–. ISSN 0006-2510
Gaudy Night is a mystery novel by Dorothy L. Sayers, the tenth featuring Lord Peter Wimsey, the third including Harriet Vane; the dons of Harriet Vane's alma mater, the all-female Shrewsbury College, have invited her back to attend the annual Gaudy celebrations. However, the mood turns sour when someone begins a series of malicious acts including poison-pen messages, obscene graffiti and wanton vandalism. Harriet asks her old friend Wimsey to investigate. Harriet Vane returns with trepidation to her alma mater, Shrewsbury College, Oxford to attend the Gaudy dinner. Expecting hostility because of her notoriety, she is surprised to be welcomed warmly by the dons, rediscovers her old love of the academic life. Harriet's short stay is, marred by her discovery of a sheet of paper with an offensive drawing, a poison pen message referring to her as a "dirty murderess"; some time the Dean of Shrewsbury writes to ask for her help. There has been an outbreak of vandalism and anonymous letters, fearing for the college's reputation if this becomes public knowledge, the Dean wants someone to investigate confidentially.
Harriet, herself a victim of poison-pen letters since her trial, reluctantly agrees, returns to spend some months in residence, ostensibly to do research on Sheridan Le Fanu and to assist a don with her book. As she wrestles with the case, trying to narrow down the list of suspects who might be responsible for poison-pen messages, obscene graffiti, wanton vandalism including the destruction of a set of scholarly proofs, the crafting of vile effigies, she is forced to examine her ambivalent feelings about Wimsey, about love and marriage, about her attraction to academia as an intellectual and emotional refuge. Wimsey arrives in Oxford to help, she gains a new perspective from those who know him, including his nephew, an undergraduate at the university; the attacks build to a crisis. There is an attempt to drive a vulnerable student to suicide and a physical assault on Harriet that kills her; the perpetrator is unmasked as Annie Wilson, one of the college scouts, revealed to be the widow of a disgraced University of York academic.
Her husband's academic fraud had been exposed by an examiner, destroying his career and driving him to suicide. The examiner moved to Shrewsbury College, the widow's campaign has been her revenge against the examiner in particular and more against intellectual women who move outside what she sees as their proper domestic sphere. At the end of the book, Harriet accepts Wimsey's proposal of marriage. Harriet Vane – protagonist, a mystery writer Lord Peter Wimsey – protagonist, an aristocratic amateur detective Letitia Martin – Dean of Shrewsbury College Helen de Vine – new Research Fellow at Shrewsbury College Miss Lydgate – Harriet's former tutor Dr Baring – Warden of Shrewsbury College Miss Hillyard – history don at Shrewsbury College Phoebe Tucker – Harriet's old college friend Viscount Saint-George – Lord Peter's nephew, an undergraduate at Christ Church, Oxford Reggie Pomfret – undergraduate at Queen's College Miss Burrows – College librarian Annie Wilson – scout at Shrewsbury College Padgett – Head Porter at Shrewsbury College Bunter – Lord Peter's manservant A'gaudy', at the University of Oxford, is a college feast a reunion for its alumni.
The term'gaudy night' appears in Shakespeare's Antony and Cleopatra: "Let's have one other gaudy night: call to me / All my sad captains. Writing in 1936, George Orwell disagreed with the opinion of an Observer critic who felt that that Gaudy Night had put Miss Sayers "definitely among the great writers". Orwell concluded, to the contrary, that "her slickness in writing has blinded many readers to the fact that her stories, considered as detective stories, are bad ones, they lack the minimum of probability that a detective story ought to have, the crime is always committed in a way, tortuous and quite uninteresting”. Although no murder occurs in Gaudy Night, it includes a great deal of suspense and psychological thrills; the narrative is interwoven with a love story and an examination of women's struggles to enlarge their roles and achieve some independence within the social climate of 1930s England, the novel has been described as "the first feminist mystery novel". Jacques Barzun stated. Harriet Vane and Saint-George, the undergraduate nephew of Lord Peter, help give variety, the college setting justifies good intellectual debate.
The motive is magnificently orated on by the culprit in a scene, a striking set-piece. And though the Shrewsbury dons are sometimes hard to distinguish one from another, the College architecture is good". Gaudy Night deals with a number of philosophical themes, such as the right relation between love and independence or between principles and personal loyalties. Susan Haack has an essay on Gaudy Night as a philosophical novel; the issue of women's right to academic education is central to the book's plot. The lecturers of Shrewsbury College are veterans of the prolonged struggle for academic degrees for women, which Oxford granted only reluctantly; the Fellows of the college are surprised and a bit dismayed at the attitude of their students, who take for granted this right for which such a hard struggle had to be fought. Sayers had herself been one of the first women to obtain an Oxford university degree, having being awarded first-class honours in the mediaeval literature examinations of 1915.
She attended the basis for the fictional Shrewsbury College of the plot. The book was adapte