Vinyl

In chemistry, vinyl or ethenyl is the functional group −CH=CH₂, namely the ethylene molecule (H₂C=CH₂) minus one hydrogen atom. The name is also used for any compound containing that group, namely R−CH=CH₂ where R is any other group of atoms.

An industrially important example is vinyl chloride, precursor to PVC, a plastic commonly known as vinyl.

Vinyl is one of the alkenyl functional groups. On a carbon skeleton, sp²-hybridized carbons or positions are often called vinylic. Allyls, acrylates and styrenics contain vinyl groups. (A styrenic crosslinker with two vinyl groups is called divinyl benzene.)

Etymology

The etymology of vinyl is the Latin vinum = "wine", because of its relationship with alcohol (in its original sense of ethyl alcohol). The term "vinyl" was coined by the German chemist Hermann Kolbe in 1851.

Vinyl polymers

Vinyl groups can polymerize with the aid of a radical initiator or a catalyst, forming vinyl polymers. In these polymers, the double bonds of the vinyl monomers turn into single bonds and the different monomers are joined by single bonds. Vinyl groups do not exist in vinyl polymer; the term refers to the precursor. It is sometimes important to ascertain the absence of unreacted vinyl monomer in the final product when the monomer is toxic or reduces the performance of the plastic. The following table gives some examples of vinyl polymers.

Billboard charts

The Billboard charts tabulate the relative weekly popularity of songs or albums in the United States and elsewhere. The results are published in Billboard magazine. Billboard biz, the online extension of the Billboard charts, provides additional weekly charts. There are also Year End charts.

History, methods and description

On January 4, 1936, Billboard magazine published its first music hit parade. The first Music Popularity Chart was calculated in July 1940. A variety of song charts followed, which were eventually consolidated into the Hot 100 by mid-1958. The Hot 100 currently combines single sales, radio airplay, digital downloads, and streaming activity (including data from YouTube and other video sites). All of the Billboard charts use this basic formula. What separates the charts is which stations and stores are used; each musical genre has a core audience or retail group. Each genre's department at Billboard is headed up by a chart manager, who makes these determinations.