the work of Thies Thiemann shows a method to produce acid chlorides through the system of triphenylphosphine and bromotrichloromethane. There might be a mixture of bromide and chlorides on the end product as he explains. I've used this method, no heat is required , at room temperature conditions, no gas emitions no acidic conditions , as found when thyonil chloride is used.

http://www.usc.es/congresos/ecsoc/15/hall_a_GOS/a002/index.pdf

The enzymatic conversion can process benzylic alcohols to benzoic acids, than you can make benzylic chloride by traditional chemical method. Also, dehalogenases can substitute the alcohol group by an halogen group (mainly chloride), usually the -OH part of an acid remains untouched by those enzymes.

I agree with Prof. Abreu. And With phosphorus tribromide is anotheh way. Smetimes, benzylic alcohols are reaction with a substrate by "one pot synthesis" method. It depends on the activity of the substrate and the method.

May be try cyanuryl chloride in DMF, But see the compactability of cyanuryl chloride in DMF before go ahead

But another my question is if you start with chiral alcohol what will be the ee you will end up with??

Simply by adding thionyl chloride

The greenest way should avoid the use of chloride or bromide.

In order to use benzyl group as a protecting group you should try the C-H activation of toluene. See for example the recent work of Yanghui Zhang et al. on benzylation of carboxylic acids in Org. Lett. 15 (2013) 4098–4101.

DOI: 10.1021/ol401687f

The greenest way should avoid the use of chloride or bromide.

In order to use benzyl group as a protecting group you should try the C-H activation of toluene. See for example the recent work of Yanghui Zhang et al. on benzylation of carboxylic acids in Org. Lett. 15 (2013) 4098–4101.

DOI: 10.1021/ol401687f