What are the practices to naming organic chemicals by abbreviations? Is there a preferred method to writing organic chemicals by abbreviation?

I am finding it hard to decipher the methods I see in writing.

For example $\ce{EtOH}$ is ethanol, which makes sense, but $\ce{PhAc}$ is acetophenone, where the constituents appear to be backwards. 

What about more complicated chemicals like 1,1-diphenylethanol, would $\ce{EtPh2OH}$ be considered appropriate, or maybe $\ce{Ph2EtOH}$?
The only accepted practice without any further constraints is to only use element symbols and sum or constitution formulae. Taking your and a few other examples, that would result in:


$\ce{C2H5OH}$ or $\ce{H3CCH2OH}$
$\ce{C6H5COCH3}$
$\ce{H3C(C6H5)2COH}$
$\ce{H3CCOOC2H5}$
$\ce{(CH3)3COCH3}$


The more complicated these get the less clear everything is. Thus, many people make use of a set of common abbreviations. However, these must be defined in a list of abbreviations, footnotes or wherever.


$\ce{EtOH}$
$\ce{PhAc}$[1]
$\ce{MePh2COH}$
$\ce{EtOAc}$
$\ce{$t$BuOMe}$


Where the symbols $\ce{Et, Ph, Ac, Me, $t$Bu}$ would need to be defined to mean ethyl, phenyl, acetyl, methyl and tert-butyl, respectively.

Finally, of course, you can suggest other common or your own abbreviations and use them (consistently!). For example, in my group it is rather common to abbreviate $\ce{EtOAc}$ as $\ce{EE}$ (because of its retained German name Essigester). Or a common way to denote the last compound in that list is $\ce{MTBE}$ or $\ce{TBME}$ (methyl-tert-butylether or tert-butylmethylether). Again, these abbreviations must be defined in footnotes or a list of abbreviations in best practice.

Finally note that an abbrevation typically includes all the hydrogens. Thus, methyl is always $\ce{CH3}$; $\ce{MeCl}$ is permissable for chloromethane but $\ce{MeCl2}$ does not mean dichloromethane. Consequently, neither $\ce{EtPh2OH}$ nor $\ce{Ph2EtOH}$ are permissable for 1,1-diphenylethanol, since carbon $\ce{C{1}}$ has no remaining hydrogens (not 2 as $\ce{CH3CH2}$ — ethyl — would imply).



[1]: Note that $\ce{Ac}$ can also mean actinium. If your paper uses actinium anywhere, do not use $\ce{Ac}$ as an abbreviation for acetyl or it shall cause confusion. The same is true for $\ce{Pr}$ and praseodymium and a few even less common others.